STEM, INC., 10-K filed on 2/28/2022
Annual Report
v3.22.0.1
Cover - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Feb. 17, 2022
Jun. 30, 2021
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2021    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity Registrant Name STEM, INC.    
Entity Incorporation, State or Country Code DE    
Entity File Number 333-251397    
Entity Tax Identification Number 85-1972187    
Entity Address, Address Line One 100 California St., 14th Fl    
Entity Address, City or Town San Francisco    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 94111    
Country Region 1    
City Area Code 877    
Local Phone Number 374-7836    
Title of 12(b) Security Common Stock, par value $0.0001    
Trading Symbol STEM    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 4,998
Entity Common Stock, Shares Outstanding   153,443,756  
Documents Incorporated by Reference Certain information required to be furnished pursuant to Part III of this Form 10-K is set forth in, and is incorporated by reference from, Stem’s definitive proxy statement for its 2022 Annual Meeting of Stockholders, to be filed by Stem with the Securities and Exchange Commission (“SEC”) pursuant to Regulation 14A within 120 days after December 31, 2021 (the “2022 Proxy Statement”).    
Entity Central Index Key 0001758766    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Amendment Flag false    
v3.22.0.1
Audit Information
 12 Months Ended
Dec. 31, 2021
Audit Information [Abstract]  
Auditor Firm ID 34
Auditor Name DELOITTE & TOUCHE LLP
Auditor Location San Francisco, California
v3.22.0.1
CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Current assets:    
Cash and cash equivalents $ 747,780 $ 6,942
Short-term investments 173,008 0
Accounts receivable, net 61,701 13,572
Inventory, net 22,720 20,843
Other current assets (includes $213 and $123 due from related parties as of December 31, 2021 and December 31, 2020, respectively) 18,641 7,920
Total current assets 1,023,850 49,277
Energy storage systems, net 106,114 123,703
Contract origination costs, net 8,630 10,404
Goodwill 1,741 1,739
Intangible assets, net 13,966 12,087
Operating leases right-of-use assets 12,998 358
Other noncurrent assets 24,531 8,282
Total assets 1,191,830 205,850
Current liabilities:    
Accounts payable 28,273 13,749
Accrued liabilities 25,993 16,072
Accrued payroll 7,453 5,976
Notes payable, current portion 0 33,683
Convertible promissory notes (includes $0 and $45,271 due to related parties as of December 31, 2021 and December 31, 2020, respectively) 0 67,590
Financing obligation, current portion 15,277 14,914
Deferred revenue, current portion 9,158 36,942
Other current liabilities (includes $306 and $399 due to related parties as of December 31, 2021 and December 31, 2020, respectively) 1,813 1,589
Total current liabilities 87,967 190,515
Deferred revenue, noncurrent 28,285 15,468
Asset retirement obligation 4,135 4,137
Notes payable, noncurrent 1,687 4,612
Convertible notes, noncurrent 316,542 0
Financing obligation, noncurrent 73,204 73,128
Warrant liabilities 0 95,342
Lease liability, noncurrent 12,183 57
Total liabilities 524,003 383,259
Commitments and contingencies
Stockholders’ equity (deficit):    
Preferred stock, $0.0001 par value; 1,000,000 shares authorized as of December 31, 2021 and December 31, 2020, respectively; 0 shares issued and outstanding as of December 31, 2021 and December 31, 2020, respectively 0 0
Common stock, $0.0001 par value; 500,000,000 shares authorized as of December 31, 2021 and December 31, 2020; 144,671,624 and 40,202,785 issued and outstanding as of December 31, 2021 and December 31, 2020, respectively 14 4
Additional paid-in capital 1,176,845 230,620
Accumulated other comprehensive income (loss) 20 (192)
Accumulated deficit (509,052) (407,841)
Total stockholders’ equity (deficit) 667,827 (177,409)
Total liabilities and stockholders’ equity (deficit) $ 1,191,830 $ 205,850
v3.22.0.1
CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Statement of Financial Position [Abstract]    
Due from related parties $ 213 $ 123
Convertible promissory notes, due to related parties 0 45,271
Other current liabilities, due to related parties $ 306 $ 399
Preferred stock, par value (in dollars per share) $ 0.0001 $ 0.0001
Preferred stock, shares authorized (in shares) 1,000,000 1,000,000
Preferred stock, shares issued (in shares) 0 0
Preferred stock, shares outstanding (in shares) 0 0
Common stock, par value (in dollars per share) $ 0.0001 $ 0.0001
Common stock, shares authorized (in shares) 500,000,000 500,000,000
Common stock, shares issued (in shares) 144,671,624 40,202,785
Common stock, shares outstanding (in shares) 144,671,624 40,202,785
v3.22.0.1
CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Total revenue $ 127,371 $ 36,307 $ 17,552
Cost of revenue 126,124 40,219 20,812
Gross margin 1,247 (3,912) (3,260)
Operating expenses:      
Sales and marketing 19,950 14,829 17,462
Research and development 22,723 15,941 14,703
General and administrative 41,648 14,705 12,425
Total operating expenses 84,321 45,475 44,590
Loss from operations (83,074) (49,387) (47,850)
Other income (expense), net:      
Interest expense (17,395) (20,806) (12,548)
Loss on extinguishment of debt (5,064) 0 0
Change in fair value of warrants and embedded derivative 3,424 (84,455) 1,493
Other income (expenses), net 898 (1,471) (503)
Total other income (expense) (18,137) (106,732) (11,558)
Income (loss) before income taxes (101,211) (156,119) (59,408)
Income tax expense 0 (5) (6)
Net loss $ (101,211) $ (156,124) $ (59,414)
Net loss per share attributable to common shareholders, basic (in dollars per share) $ (0.96) $ (4.13) $ (1.51)
Net loss per share attributable to common shareholders, diluted (in dollars per share) $ (0.96) $ (4.13) $ (1.51)
Weighted-average shares used in computing net loss per share, basic (in shares) 105,561,139 40,064,087 42,811,383
Weighted-average shares used in computing net loss per share, diluted (in shares) 105,561,139 40,064,087 42,811,383
Service revenue      
Total revenue $ 20,463 $ 15,645 $ 13,482
Cost of revenue 28,177 21,187 16,958
Hardware revenue      
Total revenue 106,908 20,662 4,070
Cost of revenue $ 97,947 $ 19,032 $ 3,854
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CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Statement of Comprehensive Income [Abstract]      
Net loss $ (101,211) $ (156,124) $ (59,414)
Other comprehensive income (loss):      
Unrealized loss on available-for-sale securities (175) 0 0
Foreign currency translation adjustment 387 (246) 54
Total comprehensive income (loss) $ (100,999) $ (156,370) $ (59,360)
v3.22.0.1
CONSOLIDATED STATEMENTS OF STOCKHOLDERS’EQUITY (DEFICIT) - USD ($)
$ in Thousands
Total
Convertible Notes
Warrant
Previously Reported
Retroactive application of recapitalization
Series 1 Convertible Preferred Stock
Series 1 Convertible Preferred Stock
Previously Reported
Series 1 Convertible Preferred Stock
Retroactive application of recapitalization
Common Stock
Common Stock
Convertible Notes
Common Stock
Warrant
Common Stock
Previously Reported
Common Stock
Retroactive application of recapitalization
Additional Paid-In Capital
Additional Paid-In Capital
Convertible Notes
Additional Paid-In Capital
Warrant
Additional Paid-In Capital
Previously Reported
Additional Paid-In Capital
Retroactive application of recapitalization
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss)
Previously Reported
Accumulated Other Comprehensive Income (Loss)
Retroactive application of recapitalization
Accumulated Deficit
Accumulated Deficit
Previously Reported
Accumulated Deficit
Retroactive application of recapitalization
Beginning balance (in shares) at Dec. 31, 2018 0     186,466,181 (186,466,181)                                      
Beginning balance at Dec. 31, 2018 $ 0     $ 218,931 $ (218,931)                                      
Ending balance (in shares) at Dec. 31, 2019 0                                              
Ending balance at Dec. 31, 2019 $ 0                                              
Beginning balance (in shares) at Dec. 31, 2018           0 3,405 (3,405) 42,223,732     9,583,163 32,640,569                      
Beginning balance at Dec. 31, 2018 8,890     $ (210,041) $ 218,931 $ 0 $ 0 $ 0 $ 3     $ 0 $ 3 $ 219,483     $ 555 $ 218,928 $ 0 $ 0 $ 0 $ (210,596) $ (210,596) $ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]                                                
Effect of exchange transaction (in shares)                 (3,368,264)                              
Effect of exchange transaction (4,990)                         (15,946)               10,956    
Issuance of warrants to purchase common stock 1,217                         1,217                    
Issuance of shares upon conversion of promissory note (in shares)                 4,245,330                              
Issuance of shares upon conversion of promissory note 28,144                         28,144                    
Settlement of litigation (in shares)                 (2,905)                              
Issuance of shares upon exercise of stock options and warrants (in shares)                 91,302                              
Issuance of common stock upon exercise of stock options and warrants 36                         36                    
Stock-based compensation 1,531                         1,531                    
Unrealized loss on available-for-sale securities 0                                              
Foreign currency translation adjustment 54                                   54          
Net loss (59,414)                                         (59,414)    
Ending balance (in shares) at Dec. 31, 2019           0     43,189,195                              
Ending balance at Dec. 31, 2019 (24,532)         $ 0     $ 3         234,465         54     (259,054)    
Increase (Decrease) in Stockholders' Equity [Roll Forward]                                                
Effect of exchange transaction (in shares)                 (3,448,648)                              
Effect of exchange transaction (3,268)                         (10,605)               7,337    
Cancellation of exchange transaction by shareholder (in shares)                 184,520                              
Recognition of beneficial conversion feature related to convertible notes 1,629                         1,629                    
Issuance of warrants to purchase common stock 168                         168                    
Issuance of shares upon exercise of stock options and warrants (in shares)                 277,718                              
Issuance of common stock upon exercise of stock options and warrants 422               $ 1         421                    
Stock-based compensation 4,542                         4,542                    
Unrealized loss on available-for-sale securities 0                                              
Foreign currency translation adjustment (246)                                   (246)          
Net loss (156,124)                                         (156,124)    
Ending balance (in shares) at Dec. 31, 2020           0     40,202,785                              
Ending balance at Dec. 31, 2020 (177,409)         $ 0     $ 4         230,620         (192)     (407,841)    
Increase (Decrease) in Stockholders' Equity [Roll Forward]                                                
Merger and PIPE financing (in shares)                 70,428,326                              
Merger and PIPE financing 248,144               $ 7         248,137                    
Conversion of securities into common stock (in shares)                   10,921,548 2,759,970                          
Conversion of securities into common stock   $ 77,748 $ 60,568             $ 1         $ 77,747 $ 60,568                
Exchange of warrants into common stock (in shares)                 4,683,349                              
Exchange of warrants into common stock 168,647               $ 1         168,646                    
Issuance of common stock warrants for services 9,183                         9,183                    
Public Warrant exercises (in shares)                 12,638,723                              
Public Warrant exercises 312,116               $ 1         312,115                    
Issuance of 2028 Convertible Notes, net 130,979                         130,979                    
Purchase of capped call options $ (66,700)                         (66,700)                    
Stock option exercises, net of statutory tax withholdings (in shares) 3,235,713               2,667,384                              
Stock option exercises, net of statutory tax withholdings $ (9,574)                         (9,574)                    
Legacy stock warrant exercises (in shares)                 369,539                              
Legacy stock warrant exercises 418                         418                    
Stock-based compensation 14,706                         14,706                    
Unrealized loss on available-for-sale securities (175)                                   (175)          
Foreign currency translation adjustment 387                                   387          
Net loss (101,211)                                         (101,211)    
Ending balance (in shares) at Dec. 31, 2021           0     144,671,624                              
Ending balance at Dec. 31, 2021 $ 667,827         $ 0     $ 14         $ 1,176,845         $ 20     $ (509,052)    
v3.22.0.1
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
OPERATING ACTIVITIES      
Net loss $ (101,211) $ (156,124) $ (59,414)
Adjustments to reconcile net loss to net cash used in operating activities:      
Depreciation and amortization expense 24,473 17,736 13,889
Non-cash interest expense, including interest expenses associated with debt issuance costs 9,648 10,044 4,759
Stock-based compensation 13,546 4,542 1,531
Change in fair value of warrant liability and embedded derivative (3,424) 84,455 (1,493)
Noncash lease expense 896 589 906
Accretion expense 229 217 303
Impairment of energy storage systems 4,320 1,395 295
Issuance of warrants for services 9,183 0 0
Net (accretion of discount) amortization of premium on investments 664 0 0
Other (50) (129) (76)
Changes in operating assets and liabilities:      
Accounts receivable (48,125) (6,988) (5,112)
Inventory (1,877) (17,263) (1,553)
Other assets (24,783) (5,329) (1,860)
Right-of-use assets (199) 0 0
Contract origination costs, net (2,622) (2,552) (1,302)
Accounts payable and accrued expenses 33,462 5,684 10,562
Deferred revenue (14,967) 31,682 9,007
Lease liabilities (303) (646) (230)
Other liabilities (126) (984) 110
Net cash used in operating activities (101,266) (33,671) (29,678)
INVESTING ACTIVITIES      
Purchase of available-for-sale investments (189,858) 0 0
Sale of available-for-sale investments 16,011 0 0
Purchase of energy storage systems (3,604) (6,196) (40,995)
Capital expenditures on internally-developed software (5,970) (5,828) (5,356)
Purchase of equity method investment (1,212) 0 0
Purchase of property and equipment (600) (12) (7)
Net cash used in investing activities (185,233) (12,036) (46,358)
FINANCING ACTIVITIES      
Proceeds from exercise of stock options and warrants 148,532 422 36
Payments for taxes related to net share settlement of stock options (12,622) 0 0
Net contributions from Merger and PIPE financing, net of transaction costs of $58,061 550,322 0 0
Proceeds from financing obligations 7,839 16,222 32,310
Repayment of financing obligations (9,587) (10,689) (7,309)
Proceeds from issuance of convertible notes, net of issuance costs of $14,299, $240 and $2,308 for the years ended December 31, 2021, 2020 and 2019, respectively 446,827 33,081 63,250
Purchase of capped call options (66,700) 0 0
Proceeds from issuance of notes payable, net of issuance costs of $0, $1,502 and $0 for the years December 31, 2021, 2020 and 2019, respectively 3,930 23,498 4,710
Repayment of notes payable (41,446) (22,240) (25,796)
Net cash provided by financing activities 1,027,095 40,294 67,201
Effect of exchange rate changes on cash and cash equivalents 242 (534) (170)
Net increase (decrease) in cash and cash equivalents 740,838 (5,947) (9,005)
Cash and cash equivalents, beginning of period 6,942 12,889 21,894
Cash and cash equivalents, end of period 747,780 6,942 12,889
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION      
Cash paid for interest 10,188 9,665 8,937
Cash paid for income taxes 0 2 3
NON-CASH INVESTING AND FINANCING ACTIVITIES      
Change in asset retirement costs and asset retirement obligation 231 1,839 (636)
Exchange of warrants for common stock 168,647 0 0
Conversion of warrants upon Merger 60,568 0 0
Conversion of convertible notes upon Merger 77,748 0 0
Conversion of accrued interest into outstanding note payable 337 644 0
Right-of-use asset obtained in exchange for lease liability 13,337 0 0
Settlement of warrant liability into common stock due to exercise 167,050 0 0
Settlement of warrant liability into common stock due to redemption 2,121 0 0
Issuance of common stock warrants 0 168 1,216
Stock-based compensation capitalized to internal-use software 1,160 0 0
Purchase of energy storage systems in accounts payable 0 1,806 950
Conversion of convertible promissory notes and accrued interest into Series D preferred stock $ 0 $ 0 $ 28,144
v3.22.0.1
CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Transaction costs $ 58,061    
Noncash lease expense 896 $ 589 $ 906
Convertible Notes      
Payment of debt issuance costs 14,299 240 2,308
Notes Payable      
Payment of debt issuance costs $ 0 $ 1,502 $ 0
v3.22.0.1
BUSINESS
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
BUSINESS BUSINESS
Description of the Business
Stem, Inc. and its subsidiaries (together, “Stem” or the “Company”) is one of the largest digitally connected, intelligent energy storage networks, providing customers (i) with an energy storage system, sourced from leading, global battery original equipment manufacturers (“OEMs”), that the Company delivers through its partners, including solar project developers and engineering, procurement and construction firms and (ii) through its Athena® artificial intelligence (“AI”) platform (“Athena”), with ongoing software-enabled services to operate the energy storage systems for up to 20 years. In addition, in all the markets where the Company operates its customers’ systems, the Company has agreements to manage the energy storage systems using the Athena platform to participate in energy markets and to share the revenue from such market participation.
The Company delivers its battery hardware and software-enabled services through its Athena platform to its customers. The Company’s hardware and recurring software-enabled services mitigate customer energy costs through services such as time-of-use and demand charge management optimization and by aggregating the dispatch of energy through a network of virtual power plants. The resulting network created by the Company’s growing customer base increases grid resilience and reliability through the real-time processing of market-based demand cycles, energy prices and other factors in connection with the deployment of renewable energy resources to such customers. Additionally, the Company’s energy storage solutions support renewable energy generation by alleviating grid intermittency issues and thereby reducing customer dependence on traditional, fossil fuel resources.

The Company operated as Rollins Road Acquisition Company (f/k/a Stem, Inc.) (“Legacy Stem”) prior to the Merger (as defined below). Stem, Inc. was incorporated on March 16, 2009 in the State of Delaware and is headquartered in San Francisco, California.
Star Peak Acquisition Corp. Merger
On December 3, 2020, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Star Peak Transition Corp. (“STPK”), an entity listed on the New York Stock Exchange under the trade symbol “STPK”, and STPK Merger Sub Corp., a Delaware corporation and wholly-owned subsidiary of STPK (“Merger Sub”), providing for, among other things, and subject to the conditions therein, the combination of the Company and STPK pursuant to the merger of Merger Sub with and into the Company with the Company continuing as the surviving entity (the “Merger”).

On April 28, 2021, shareholders of STPK approved the Merger, under which Stem received approximately $550.3 million, net of fees and expenses as follows (in thousands):
Recapitalization
Cash — STPK trust and working capital cash$383,383 
Cash — PIPE (as described below)225,000 
Less: transaction costs and advisory fees paid(58,061)
Merger and PIPE financing$550,322 

Immediately prior to the closing of the Merger, (i) all issued and outstanding shares of Legacy Stem preferred stock, par value $0.00001 per share (the “Legacy Stem Preferred Stock”), were converted into shares of Legacy Stem common stock, par value $0.000001 per share (the “Legacy Stem Common Stock”) in accordance with Legacy Stem’s amended and restated certificate of incorporation, (ii) all outstanding convertible promissory notes of Legacy Stem (the “Legacy Stem Convertible Notes”) were converted into Legacy Stem Preferred Stock in accordance with the terms of the Legacy Stem Convertible Notes and (iii) certain warrants issued by Legacy Stem to purchase Legacy Stem Common Stock and Legacy Stem Preferred Stock (the “Legacy Stem Warrants”) were exercised by holders into Legacy Stem Common Stock in accordance with the terms thereof. Upon the consummation of the Merger, each share of Legacy Stem common stock then issued and outstanding was canceled and converted into the right to receive shares of common stock of Stem using an exchange ratio of 4.6432.

In connection with the execution of the Merger Agreement, STPK entered into separate subscription agreements (each, a “Subscription Agreement”) with a number of investors (each a “Subscriber”), pursuant to which the Subscribers agreed to purchase, and STPK agreed to sell to the Subscribers, an aggregate of 22,500,000 shares of common stock (the “PIPE Shares”), for a purchase price of $10 per share and an aggregate purchase price of $225.0 million, in a private placement pursuant to the
subscription agreements (the “PIPE”). The PIPE investment closed simultaneously with the consummation of the Merger. The Merger is accounted for as a reverse recapitalization in accordance with U.S. generally accepted accounting principles (“GAAP”). Under this method of accounting, STPK was treated as the “acquired” company for financial reporting purposes. Accordingly, for accounting purposes, the Merger was treated as the equivalent of Stem issuing stock for the net assets of STPK, accompanied by a recapitalization. The net liabilities of STPK of $302.2 million, comprised primarily of the warrant liabilities associated with the Public and Private Placement Warrants discussed in Note 13 - Warrants, are stated at historical cost, with no goodwill or other intangible assets recorded.
Liquidity
The accompanying consolidated financial statements have been prepared in accordance with GAAP and with the instructions to Form 10-K and Regulation S-X, assuming the Company will continue as a going concern. As of December 31, 2021, the Company had cash and cash equivalents of $747.8 million, short-term investments of $173.0 million, an accumulated deficit of $509.1 million and net working capital of $935.9 million, with $15.3 million of financing obligation coming due within the next 12 months. During the year ended December 31, 2021, the Company incurred a net loss of $101.2 million and had negative cash flows from operating activities of $101.3 million. However, the net proceeds from the Merger of $550.3 million, the proceeds of $145.3 million from the exercise of Public Warrants (as described in Note 13 - Warrants), and the net proceeds of $445.7 million from the issuance of the Company’s 0.50% Green Convertible Senior Notes due 2028 (the “2028 Convertible Notes”) (as described in Note 12 - Convertible Promissory Notes) provided the Company with a significant amount of cash proceeds. As discussed in Note 21 - Subsequent Events, the Company completed the acquisition of 100% of the outstanding shares of AlsoEnergy, Inc., (“AlsoEnergy”) for an aggregate purchase price of $695.0 million, consisting of approximately 75% in cash. The Company believes that its cash position is sufficient to meet capital and liquidity requirements for at least the next 12 months after the date that the financial statements are available to be issued.
The Company’s business prospects are subject to risks, expenses, and uncertainties frequently encountered by companies in the early stages of commercial operations. Prior to the Merger, the Company had been funded primarily by equity financings, convertible promissory notes and borrowings from affiliates. The attainment of profitable operations is dependent upon future events, including obtaining adequate financing to complete the Company’s development activities, securing adequate supplier relationships, building its customer base, successfully executing its business and marketing strategy, and hiring and retaining appropriate personnel. Failure to generate sufficient revenues, achieve planned gross margins and operating profitability, control operating costs, or secure additional funding may require the Company to modify, delay or abandon some of its planned future expansion or development, or to otherwise enact operating cost reductions available to management, which could have a material adverse effect on the Company’s business, operating results and financial condition.
COVID-19
The ongoing COVID-19 pandemic has resulted and may continue to result in widespread adverse impacts on the global and U.S. economies. Ongoing government and business responses to COVID-19, along with the COVID-19 Omicron variant and resurgence of related disruptions, could have a continued material adverse effect on economic and market conditions and trigger a period of continued global and U.S. economic slowdown.

The Company’s industry is currently facing shortages and shipping delays affecting the supply of energy storage systems, batteries, modules and component parts for inverters and battery energy storage systems available for purchase. These shortages and delays can be attributed in part to the COVID-19 pandemic and resulting government action. While a majority of the Company’s suppliers have secured sufficient quantities to permit them to continue delivery and installing through the end of 2022, if these shortages and delays persist into 2023, they could adversely affect the timing of when energy storage systems can be delivered and installed and when the Company can begin to generate revenue from those systems. The Company cannot predict the full effect the COVID-19 pandemic will have on its business, cash flows, liquidity, financial condition and results of operations at this time due to numerous uncertainties. The Company will continue to monitor developments affecting its workforce, its customers and its business operations generally, and will take actions it determines are necessary in order to mitigate these effects.
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]  
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Basis of Presentation
The Company's consolidated financial statements have been prepared in accordance with GAAP.
Immaterial Out-of-Period Corrections
During the year ended December 31, 2021, the Company recorded certain out-of-period corrections related to prior interim and annual periods pertaining to the amortization of contract origination costs and valuation of energy storage systems that were decommissioned. The impact of out-of-period corrections to the year ended December 31, 2021 was an increase of $2.8 million to net loss, and increase to cost of service revenue of $1.7 million, and an increase to sales and marketing expenses of $1.1 million. The following table presents the amount of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, and the amounts and periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatementYear Ended December 31,
 20202019
Periods prior to 2019
Energy storage systems, net$(1.7)$(1.5)$(0.9)
Contract origination costs, net$(1.1)$(0.3)$(0.1)
Cost of service revenue$0.2 $0.6 $0.9 
Sales and marketing$0.8 $0.2 $0.1 
The Company corrected the out of period errors in the quarter ended December 31, 2021. The impact of the out-of-period correction for the quarter ended December 31, 2021 included corrections for the prior quarterly periods presented below. The impact to the quarter ended December 31, 2021, was an increase of $4.2 million to net loss, increase to cost of service revenue of $1.8 million and increase to sales and marketing expenses of $2.4 million. The following table presents the amounts of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, as well as the quarterly periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatement
 
Quarter ended September 30, 2021
Quarter ended
June 30, 2021
Quarter ended March 31, 2021
Energy storage systems, net$(1.8)$(1.7)$(1.7)
Contract origination costs, net$(2.4)$(1.6)$(1.4)
Cost of service revenue$0.1 $— $— 
Sales and marketing$0.8 $0.2 $0.3 
The errors and out of period corrections had no impact to the Company’s net cash used in operating activities for any of the periods presented. The Company performed a quantitative and qualitative evaluation of these out-of-period adjustments and has concluded that the amounts are not material in relation to the year ended December 31, 2021, or any prior interim or annual periods.
Reclassifications
Certain prior year amounts have been reclassified for consistency with the current year presentation. Such reclassifications have no impact on previously reported net loss, stockholders' equity (deficit), or cash flows.
Principles of Consolidation
The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries, and consolidated variable interest entities (“VIEs”). All intercompany balances and transactions have been eliminated in consolidation.
Variable Interest Entities
The Company forms special purpose entities (“SPEs”), some of which are VIEs, with its investors in the ordinary course of business to facilitate the funding and monetization of its energy storage systems. A legal entity is considered a VIE if it has either a total equity investment that is insufficient to finance its operations without additional subordinated financial support or whose equity holders lack the characteristics of a controlling financial interest. The Company’s variable interests arise from contractual, ownership, or other monetary interests in the entity. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as VIEs, through arrangements that do not involve controlling voting interests.
The Company consolidates a VIE if it is deemed to be the primary beneficiary. The Company determines it is the primary beneficiary if it has the power to direct the activities that most significantly impact the VIEs’ economic performance and has the obligation to absorb losses or has the right to receive benefits of the VIE that could potentially be significant to the VIE. The Company evaluates its relationships with its VIEs on an ongoing basis to determine whether it is the primary beneficiary.
Equity Method Investments
The Company has ownership interests in SPEs which it does not control. Where the Company holds an interest in these SPEs of greater than 20% and has the ability to exercise significant influence, the Company uses the equity method to account for its investments in these SPEs. Under the equity method of accounting, investments are stated at initial cost and are adjusted for subsequent additional investments and the Company’s proportionate share of earnings or losses and distributions. Such proportionate share of earnings or losses is included within other expenses, net in the consolidated statements of operations. The Company considers whether its equity method investments are impaired when events or circumstances suggest that the carrying amount may not be recoverable. An impairment charge is recognized in the consolidated statements of operations for a decline in value that is determined to be other-than-temporary. In determining if and when a decline in the fair value of these investments below their carrying value is other-than-temporary, the Company evaluates the market condition, trends of earnings and cash flows and other key measures of performance and recognizes such loss which is deemed to be other-than-temporary. No such losses have been recognized during the years ended December 31, 2021, 2020, and 2019.
Use of Estimates
The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions believed to be reasonable. Actual results could differ from those estimates and such differences could be material to the financial position and results of operations.
Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, depreciable life of energy systems; the amortization of financing obligations; deferred commissions and contract fulfillment costs; the valuation of energy storage systems, internally developed software, and asset retirement obligations; and the fair value of financial instruments, equity-based instruments, debt, warrant liabilities and embedded derivatives.
Segment Information
Operating segments are defined as components of an entity for which discrete financial information is available that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s Chief Executive Officer is the CODM. The CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. As such, management has determined that the Company operates as one operating segment that is focused exclusively on innovative technology services that transform the way energy is distributed and consumed. Net assets outside of the U.S. were less than 10% of total net assets as of December 31, 2021 and 2020.
Cash and Cash Equivalents
The Company considers all highly liquid investments with an original maturity date of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents are maintained at financial institutions. The Company maintains all cash in a highly liquid form to meet current obligations.
Short-Term Investments
Investments with a maturity date greater than three months that the Company intends to convert to cash or cash equivalents within a year or less are classified as short-term investments in the Company’s consolidated balance sheets. Additionally, in accordance with ASC 320, Investments - Debt Securities, the Company has classified all short-term investments as available-for-sale securities and changes in fair market value are reported in other comprehensive income (loss).
The Company utilizes its short-term investments as an alternative form of cash and, if the cash needs arise, could liquidate the investments at any point in time regardless of the contractual maturity of the investments. All of the Company’s investments are tradable on an active market and could be sold at fair value at any point in time.
Accounts Receivable, Net
Accounts receivable are recorded at the invoiced amount, net of allowance for doubtful accounts. Accounts receivable also include unbilled accounts receivable, which is composed of the monthly energy optimization services provided and recognized but not yet invoiced as of the end of the reporting period. The allowance for doubtful accounts is based on the Company’s best estimate and is determined based upon a variety of factors, including analyses of specific customer receivables, aging, and overall assessments of collectability. Accounts receivable balances are charged against the allowance when the Company believes it is probable that the receivable will not be recovered. The allowance for doubtful accounts balance was $0.1 million as of each December 31, 2021 and 2020.
Concentrations of Credit Risk and Other Uncertainties
Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company’s cash balances are primarily invested in money market funds or on deposit at high credit quality financial institutions in the U.S. The Company’s cash and cash equivalents are held at financial institutions where account balances may at times exceed federally insured limits. Management believes the Company is not exposed to significant credit risk due to the financial strength of the depository institution in which the cash is held. The Company has no financial instruments with off-balance sheet risk of loss.
At times, the Company may be subject to a concentration of credit risk in relation to certain customers due to the purchase of large energy storage systems made by such customers. The Company routinely assesses the creditworthiness of its customers. The Company has not experienced any material losses related to receivables from individual customers, or groups of customers during the years ended December 31, 2021, 2020 and 2019. The Company does not require collateral. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable.
Significant Customers
A significant customer represents 10% or more of the Company’s total revenue or accounts receivable, net balance at each reporting date. For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:
Accounts ReceivableRevenue
December 31,Year Ended December 31,
20212020202120202019
Customers:
Customer A23 %*11 %**
Customer B15 %*10 %12 %*
Customer C13 %17 %10 %25 %*
Customer D*30 %***
Customer E*20 %***
*Total less than 10% for the respective period
Inventory
Inventory consists of batteries and related components either in-process at the Company’s OEM suppliers or as a finished product at the Company’s warehouse, which are sold and delivered directly to customers under the Company’s partnership arrangements as individual assets or assembled systems. Inventory is stated at lower of cost or net realizable value with cost being determined by the specific identification method. The Company periodically reviews its inventory for potentially slow-moving or obsolete items and writes down specific items in inventory to net realizable value based on its assessment of market conditions.
Energy Storage Systems, Net
The Company sells energy optimization services to host customers through the use of energy storage systems installed at customer locations. The Company determined that it does not transfer control of these energy storage systems to the customer, which are operated and controlled via the Company’s proprietary cloud-based software (“SaaS”) platform; therefore, these
energy storage systems do not qualify as a leased asset. The energy storage systems are stated at cost, less accumulated depreciation and impairment (as applicable).
Energy storage systems, net is comprised of equipment costs, which include components such as batteries, inverters, and other electrical equipment, and associated design, installation, and interconnection costs required to begin providing the energy optimization services to customers.
Depreciation of the energy storage systems is a component of cost of revenues within the consolidated statements of operations and is calculated using the straight-line method over the estimated useful lives of the energy storage systems, or 10 years, once the respective energy storage systems have been installed and interconnected to the power grid, the Company has received permission to operate, and the Company has begun to provide energy optimization services to the customer (i.e., energy storage system is live). Repairs and maintenance costs are expensed as incurred. Impairment charges related to energy storage system that were determined to no longer be recoverable totaled $4.3 million, $1.4 million and $0.3 million for the years ended December 31, 2021, 2020, and 2019, respectively.
Contract Origination Costs, Net
Contract origination costs, net is stated at gross contract origination costs less accumulated amortization. Contract origination costs consists of sales commissions earned by the Company’s sales team, as well as related payroll taxes and other relevant fringe benefits that are direct, incremental, and recoverable costs of obtaining a contract with a customer. As a result, these amounts have been capitalized on the consolidated balance sheets. The Company deferred incremental costs of obtaining a contract of $3.0 million and $2.6 million during the years ended December 31, 2021 and 2020, respectively.
Contract origination costs are amortized over the expected period of benefit. The period of benefit is estimated by considering factors such as the timing of fulfillment of performance obligations, historical customer attrition rates, the useful life of the Company’s technology, and the impact of competition in its industry. Amortization of contract costs were $3.9 million, $0.8 million and $0.5 million for the years ended December 31, 2021, 2020, and 2019, respectively, and are included in sales and marketing expense in the accompanying consolidated statements of operations. The Company also recorded $0.5 million, $0.1 million and $0.5 million in impairment losses in sales and marketing expense in the statements of operations related to the contract origination costs that were determined to no longer be recoverable during the years ended December 31, 2021, 2020, and 2019, respectively.
Business Combinations
The Company accounts for business acquisitions under ASC 805, Business Combinations. The total purchase consideration for an acquisition is measured as the fair value of the assets given, equity instruments issued and liabilities assumed at the acquisition date. Costs that are directly attributable to the acquisition are expensed as incurred. Identifiable assets (including intangible assets), liabilities assumed (including contingent liabilities) and noncontrolling interests in an acquisition are measured initially at their fair values at the acquisition date. The Company recognizes goodwill if the fair value of the total purchase consideration and any noncontrolling interests is in excess of the net fair value of the identifiable assets acquired and the liabilities assumed. The Company recognizes a bargain purchase gain within other income (expense), net, on the consolidated statement of operations if the net fair value of the identifiable assets acquired and the liabilities assumed is in excess of the fair value of the total purchase consideration and any noncontrolling interests. The Company includes the results of operations of the acquired business in the consolidated financial statements beginning on the acquisition date.
Intangible Assets
Internal-use software
The Company capitalizes costs incurred in the development of internal-use software during the application development stage. Costs related to preliminary project activities and post-implementation activities are expensed as incurred. Capitalized internal-use software is amortized on a straight-line basis over the estimated useful life of the software once it is ready for its intended use. The estimated useful life of costs capitalized is generally five years. The Company recorded amortization for internal-use software of $5.0 million, $4.0 million and $3.0 million in cost of revenues in the accompanying consolidated statements of operations for the years ended December 31, 2021, 2020, and 2019, respectively.
Finite-lived Intangible Assets
Finite-lived intangible assets consist of developed technology acquired in a business combination. Finite-lived intangible assets acquired in business combinations are initially recorded at fair value and subsequently presented net of accumulated
amortization. These intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company amortizes its developed technology over five years. These intangible assets were fully amortized as of December 31, 2021. Amortization of these intangible assets was not material for the years ended December 31, 2020 and 2019.
Impairment of Long-Lived Assets
The Company reviews its long-lived assets, which primarily consist of energy storage systems, right-of- use assets, and finite-lived intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable or that the useful life is shorter than originally estimated. Recoverability of assets is measured by comparing the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset over its remaining useful life.
If such assets are impaired, the impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. If the useful life is shorter than originally estimated, the Company depreciates or amortizes the remaining carrying value over the revised shorter useful life. Assets to be disposed of by sale are reflected at the lower of their carrying amount or fair value less cost to sell.
Leases
The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases along with the initial measurement and recognition of the associated ROU assets and lease liabilities is performed at the lease commencement date. The measurement of ROU assets and lease liabilities is based on the present value of future lease payments over the lease term. The ROU asset also includes the effect of any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable.
As the implicit rate in the Company’s leases is generally unknown, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The Company considers its credit risk, term of the lease, total lease payments and adjusts for the impacts of collateral, as necessary, when calculating its incremental borrowing rates. The lease terms may include options to extend or terminate the lease when it is reasonably certain the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. Variable lease payments are recorded as an expense in the period incurred.
The Company has elected to not separate lease and non-lease components for any leases within its existing classes of assets and, as a result, accounts for any lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases within its existing classes of assets with a term of 12 months or less.
Convertible Preferred Stock Warrant Liabilities
The Company evaluates whether its warrants for shares of convertible redeemable preferred stock are freestanding financial instruments that obligate the Company to redeem the underlying preferred stock at some point in the future and determined that each of its outstanding warrants for preferred stock are liability classified. The warrants are subject to re-measurement at each balance sheet date, and any change in fair value is recognized in the change in fair value of warrants and embedded derivatives in the consolidated statements of operations.
As discussed in Note 13 - Warrants, upon effectiveness of the Merger, substantially all of the outstanding convertible preferred stock warrants were converted into shares of common stock of Stem. As such, the associated warrant liability was reclassified to additional paid-in-capital upon the Merger and was no longer an outstanding Level 3 financial instrument as of December 31, 2021.

Common Stock Warrants
The Company evaluates common stock warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity. The Company assesses whether common stock warrants are freestanding financial instruments and whether they meet the criteria to be classified in stockholders’ equity, or classified as a liability. Where common stock warrants do not meet the conditions to be classified in equity, the Company assesses whether they meet the definition of a liability under ASC 815.
Common stock warrants that meet the definition of a liability are recognized on the balance sheet at fair value. Subsequent changes in their respective fair values are recognized in the consolidated statement of operations at each reporting date.
As indicated in Note 13 - Warrants, as part of STPK’s initial public offering, the Company issued Public Warrants and Private Warrants, which upon issuance met the criteria for liability classification under ASC 815.
Asset Retirement Obligations
The Company recognizes a liability for the fair value of asset retirement obligations (“ARO”) associated with its energy storage systems in the period in which there is a legal obligation associated with the retirement of such assets and the amount can be reasonably estimated. The associated asset retirement costs are capitalized as part of the carrying amount of the energy storage systems and depreciated over the asset’s remaining useful life. This liability includes costs related to the removal of its energy storage systems at the conclusion of each respective customer contract. Subsequent to initial measurement, the asset retirement liability is accreted each period and such accretion is recognized as an expense in the consolidated statements of operations. If there are changes in the estimated amount or timing of cash flows, a revision is recorded to both the asset retirement obligation and the asset retirement capitalized cost.
Financing Obligations
The Company has formed various SPEs to finance the development and construction of its energy storage systems. These SPEs, which are structured as limited liability companies, obtain financing in the form of large upfront payments from outside investors and purchase energy storage systems from the Company under master purchase agreements. The Company accounts for the large upfront payments received from the fund investor as a borrowing by recording the proceeds received as a financing obligation, which will be repaid through host customer payments and incentives received from the utilities that will be received by the investor.
The financing obligation is non-recourse once the associated energy storage systems have been placed in-service and the associated customer arrangements have been assigned to the SPE. However, the Company is responsible for any warranties, performance guarantees, accounting, performance reporting, and all other costs associated with the operation of the energy storage systems. Despite such energy storage systems being legally sold to the SPEs, the Company recognizes host customer payments and incentives as revenue during the period as discussed in Note 3 - Revenue. The amounts received by the fund investor from customer payments and incentives are recognized as interest using the effective interest method, and the balance is applied to reduce the financing obligation. The effective interest rate is the interest rate that equates the present value of the cash amounts to be received by a fund investor in relation to the underlying Projects with the present value of the cash amounts paid by the investor to the Company, adjusted for any payments made by the Company.
Fair Value of Financial Instruments
Assets and liabilities recorded at fair value in the consolidated financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. The fair value of the Company’s financial assets and liabilities reflects management’s estimate of amounts that the Company would have received in connection with the sale of the assets or paid in connection with the transfer of the liabilities in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of its assets and liabilities, the Company seeks to maximize the use of observable inputs (market data obtained from independent sources) and to minimize the use of unobservable inputs (internal assumptions about how market participants would price assets and liabilities).

Hierarchical levels which are directly related to the amount of subjectivity associated with the inputs to the valuation of these assets or liabilities are as follows:
Level 1 — Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date.
Level 2 — Inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data.
Level 3 — Unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date.
This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Assets and liabilities measured at fair value are classified in their entirety
based on the lowest level of input that is significant to their fair value measurement. The Company’s assessment of the significance of a specific input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.
Financial assets and liabilities held by the Company measured at fair value on a recurring basis as of December 31, 2021 and 2020, include cash and cash equivalents, short-term investments, warrant liabilities and embedded derivatives which are bifurcated from the host financial instrument.
Revenue Recognition
Revenues are recognized when control of the promised goods or services are transferred to the Company’s customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. The Company generates all of its revenues from contracts with its customers. The Company recognizes revenue through two types of arrangements with customers, host customer arrangements and partnership arrangements as described below.

Host Customer Arrangements
Host customer contracts are generally entered into with commercial entities that have traditionally relied on power supplied directly from the grid. Host customer arrangements consist of a promise to provide energy optimization services through the Company’s proprietary SaaS platform coupled with a dedicated energy storage system owned and controlled by the Company throughout the term of the contract. The host customer does not obtain legal title to, or ownership of the dedicated energy storage system at any point in time. The host customer is the end consumer of the energy that directly benefits from the energy optimization services provided by the Company. The term for the Company’s contracts with host customers generally ranges from 5 to 10 years, which may include certain renewal options to extend the initial contract term or certain termination options to reduce the initial contract term.
Although the Company installs an energy storage system at the host customer site in order to provide the energy optimization services, the Company directs how and for what purpose the asset is used through the operation of its SaaS platform and, as such, retains control of the energy storage system; therefore, the contract does not contain a lease. The Company determines the various energy optimization services provided throughout the term of the contract, which may include services such as remote monitoring, performance reporting, preventative maintenance and other ancillary services necessary for the safe and reliable operation of the energy storage system, are part of a combined output of energy optimization services and the Company provides a single distinct combined performance obligation representing a series of distinct days of services.
The Company determines the transaction price at the outset of the arrangement, primarily based on the contractual payment terms dictated by the contract with the customer. Fees charged to customers for energy optimization services generally consist of recurring fixed monthly payments throughout the term of the contract. In certain arrangements, the transaction price may include incentive payments that are earned by the host customer from utility companies in relation to the services provided by the Company. Under such arrangements, the rights to the incentive payments are assigned by the host customer to the Company. These incentives may be in the form of fixed upfront payments, variable monthly payments, or annual performance-based payments over the first five years of the customer contract term. Incentive payments may be contingent on approval from utility companies or actual future performance of the energy storage system.
Substantially all of the Company’s arrangements provide customers the unilateral ability to terminate for convenience prior to the conclusion of the stated contractual term or the contractual term is shorter than the estimated benefit period, which the Company has determined to be 10 years based on the estimated useful life of the underlying energy storage systems and the period over which the customer can benefit from the energy optimization services utilizing such energy storage systems. In these instances, the Company determined that upfront incentive payments received from its customers represent a material right that is, in effect, an advance payment for future energy optimization services to be recognized throughout the estimated benefit period. In contracts where the customer does not have the unilateral ability to terminate for convenience without a penalty during the estimated benefit period, the Company determined the upfront incentive payments do not represent a material right for services provided beyond the initial contractual period and are therefore a component of the initial transaction price. The Company revisits its estimate of the benefit period each reporting period. The Company’s contracts with host customers do not contain a significant financing component.
The Company transfers control of its energy optimization services to its customers continuously throughout the term of the contract (a stand-ready obligation) and revenue is recognized ratably as control of these services is transferred to its customers, in an amount that reflects the consideration the Company expects to be contractually entitled to in exchange for its services. Monthly incentive payments based on the performance of the energy storage system are allocated to the distinct month in which they are earned because the terms of the payments relate specifically to the outcome from transferring the distinct time increment (month) of service and because such amounts reflect the fees to which the Company expects to be entitled for providing energy optimization services each period, consistent with the allocation objective. Annual variable performance- based payments are estimated at the inception in the transaction price using the expected value method, which takes into consideration historical experience, current contractual requirements, specific known market events and forecasted energy storage system performance patterns, and the Company recognizes such payments ratably using a time-based measure of progress of days elapsed over the term of the contract to the extent that it is probable that a significant reversal of the cumulative revenue recognized will not occur in a future period. At the end of each reporting period, the Company reassesses its estimate of the transaction price. The Company does not begin recognition of revenue until the energy storage system is live (i.e., provision of energy optimization services has commenced) or, as it relates to incentive payments, when approval has been received from the utility company, if later.
Partnership Arrangements
Partnership arrangements consist of promises to transfer inventory in the form of an energy storage system to a “solar plus storage” project developer and separately provide energy optimization services as described previously to the ultimate owner of the project after the developer completes the installation of the project. Under partnership arrangements, the Company’s customer is the solar plus storage project developer. The customer obtains legal title to along with ownership and control of the inventory upon delivery and the customer is responsible for the installation of the project. Once installation of the project is complete, the owner of the solar plus storage project provides energy to the end consumer through a separate contractual arrangement directly with the end consumer. The term for the Company’s contracts with customers under partnership arrangements generally ranges from 10 to 20 years.
The Company determined the promise to deliver the inventory as a component of the solar plus storage project for which the customer is responsible to develop is a separate and distinct performance obligation from the promise to provide energy optimization services.
The Company determines the transaction price at the outset of the arrangement, primarily based on the contractual payment terms dictated by the contract with the customer. Fees charged for the sale of inventory generally consist of fixed fees payable upon or shortly after successful delivery to the customer. Fees charged to customers for energy optimization services consist of recurring fixed monthly payments throughout the term of the contract. The Company is responsible for designing, procuring, delivering and ensuring the proper components are provided in accordance with the requirements of the contract. Although the inventory is purchased by the Company from a third-party manufacturer, the Company determined it obtains control of the inventory prior to delivery to the customer and is the principal in the arrangement. The Company is fully responsible for responding to and correcting any customer issues related to the delivery of the inventory. The Company holds title and assumes all risks of loss associated with the inventory until the customer accepts the inventory. The Company is primarily responsible for fulfilling the delivery of the inventory to the customer, assumes substantial inventory risks and has discretion in the pricing charged to the customer. The Company has not entered into any partnership arrangements where it is not the principal in the transaction.
The Company allocates revenue between the hardware and energy storage services performance obligations based on the standalone selling price of each performance obligation. The standalone selling price for the hardware is established based on observable pricing. The standalone selling price for the energy optimization services is established using a residual value approach due to the significant variability in the services provided to each individual customer based on the specific requirements of each individual project and the lack of observable standalone sales of such services. The Company’s partnership arrangements do not contain a significant financing component.
The Company transfers control of the inventory upon delivery and simultaneous transfer of title to the customer. The Company transfers control of its energy optimization services to its customers continuously throughout the term of the contract (a stand-ready obligation), which does not commence until the customer successfully completes the installation of the project. As a result, the time frame between when the Company transfers control of the inventory to the customer upon delivery is generally several months, and can be in excess of one year, before the Company is required to perform any subsequent energy optimization services. Revenue is recognized ratably as control of these services is transferred to its customers based on a time-based output measure of progress of days elapsed over the term of the contract, in an amount that reflects the consideration the Company expects to be entitled to in exchange for its services.
In some partnership arrangements, the Company charges shipping fees for the inventory. The Company accounts for shipping as a fulfillment activity, since control transfers to the customer after the shipping is complete and includes such amounts within cost of revenue.
Cost of Revenue
Cost of Hardware Revenue
Cost of revenue related to the sale of hardware includes the cost of the hardware sold to project developers, which generally includes the cost to purchase the hardware from a manufacturer, shipping, and other costs required to fulfill the Company’s obligation to deliver the hardware to the customer location. Cost of revenue may also include any impairment of hardware held in inventory for sale to a customer. Cost of revenue related to the sale of hardware is recognized when the delivery of the hardware is completed.
Cost of Service Revenue
Cost of revenue related to energy optimization services includes depreciation of the cost of energy storage systems associated with long-term host customer contracts, which includes capitalized fulfillment costs, such as installation services, permitting and other related costs. Cost of revenue may also include any impairment of energy storage systems along with energy storage system maintenance costs associated with the ongoing services provided to customers and other amounts not qualifying for capitalization pursuant to the Company’s internal use software capitalization policy. Cost of revenue is recognized as the energy optimization and other supporting services are provided to the Company’s customers throughout the term of the contract.
Sales and Marketing
Sales and marketing expense consists primarily of payroll and other related personnel costs, including stock-based compensation, employee benefits, and travel for the Company’s sales & marketing department. These costs are recognized in the period incurred. Advertising expenses for the years ended December 31, 2021, 2020, and 2019 were not material.
Research and Development
Research and development expense consists primarily of payroll and other related personnel costs for engineers and third parties engaged in the design and development of products, third-party software, and technologies, including salaries, bonus and stock-based compensation expense, project material costs, services, and depreciation. The Company expenses research and development costs as they are incurred.
General and Administrative
General and administrative expense consists of payroll and other related personnel costs, including salaries, bonuses and stock-based compensation for executive management, legal, finance, and others. In addition, general and administrative expense includes fees for professional services and occupancy costs.
Stock-Based Compensation
The Company recognizes stock-based compensation expense related to employees over the requisite service period based on the grant-date fair value of the awards. The fair value of options granted is estimated using the Black-Scholes option valuation model. The Company recognizes the grant-date fair value of an award as compensation expense on a straight-line basis over the requisite service period, which typically corresponds to the vesting period for the award. The Company elects to account for forfeitures as they occur and, upon forfeiture of an award prior to vesting, the Company reverses any previously recognized compensation expense related to that award.
Income Taxes
The Company uses the asset and liability method of accounting for income taxes based on ASC 740, Accounting for Income Taxes. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between financial statement carrying amounts and the tax basis of existing assets and liabilities. The Company records a valuation allowance to reduce tax assets to an amount for which realization is more likely than not. There are certain charges that are not deductible for tax purposes.
In evaluating the ability to recover its deferred income tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning, and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. In the event the Company determines that it would be able to realize its deferred income tax assets in the future in excess of their net recorded amount, it would make an adjustment to the valuation allowance that would reduce the provision for income taxes. Conversely, in the event that all or part of the net deferred tax assets are determined not to be realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period such determination is made.
The Company recognizes the tax benefit from uncertain tax positions in accordance with GAAP, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s tax return. No liability related to uncertain tax positions has been recognized in the financial statements.
The Company includes interest and penalties for uncertain tax positions in the financial statements as a component of income tax expense. No accrual has been deemed necessary as of December 31, 2021 and 2020.
Foreign Currency Translation
The Company’s foreign subsidiaries financial position and results of operations are measured using the local currency as the functional currency. The functional currency is the currency of the primary economic environment in which an entity’s operations are conducted. Assets and liabilities of foreign subsidiaries are translated at exchange rates in effect as of the balance sheet date. Revenues and expenses are translated at average exchange rates in effect during the year. Translation adjustments are recorded within accumulated other comprehensive loss, a separate component of stockholders’ equity (deficit).
Net Loss Per Share Attributable to Common Stockholders
Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted- average number of common shares and common share equivalents of potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible notes, warrants, restricted stock units (“RSUs”), and common stock options are considered to be potentially dilutive securities. As the Company was in a net loss position for the years ended December 31, 2021, 2020, and 2019, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders because the effects of potentially dilutive securities are antidilutive.
Recently Adopted Accounting Standards
In August 2018, the FASB issued ASU 2018-15, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). The intent of this pronouncement is to align the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software as defined in ASC 350-40. Under ASU 2018-15, the capitalized implementation costs related to a cloud computing arrangement will be amortized over the term of the arrangement and all capitalized implementation amounts will be required to be presented in the same line items of the financial statements as the
related hosting fees. ASU 2018-15 is effective for public and private companies’ fiscal years beginning after December 15, 2019, and December 15, 2020, respectively, and interim periods within those fiscal years, with early adoption permitted. The Company adopted ASU 2018-15 as of January 1, 2021. The adoption did not have a material effect on the Company’s consolidated financial statements.
In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 was effective for public entities for interim and annual periods beginning after December 15, 2020, with early adoption permitted. ASU 2019-12 will be effective for private entities for annual periods beginning after December 15, 2021, and interim periods beginning after December 15, 2020, with early adoption permitted. The Company adopted ASU 2019-12 effective May 1, 2021. The adoption of this standard did not have a material impact on the Company's consolidated financial statements.
Recently Issued Accounting Standards
The Company will adopt ASU 2020-06 Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, effective January 1, 2022 using the modified retrospective approach. As a result of the adoption of ASU 2020-06, the 2028 Convertible Notes will no longer bifurcated into separate liability and equity components in the March 31, 2022 condensed consolidated balance sheet. Rather, the $460.0 million principal amount of the Company’s 2028 Convertible Notes will be classified only as a liability prospectively in the balance sheet. Upon adoption of ASU 2020-06, an adjustment will be recorded to the convertible notes liability component, equity component (additional paid-in-capital) and retained earnings. The cumulative effect of the change will be recognized as an adjustment to the opening balance of retained earnings at the date of adoption. The comparative information will not restated and will continue to be presented according to accounting standards in effect for those periods. The adjustment will be calculated based on the carrying amount of the 2028 Convertible Notes as if it had always been treated only as a liability. Interest expense recognized in future periods will be reduced as a result of accounting for the convertible debt instrument as a single liability measured at its amortized cost.

In June 2016, the FASB issued ASU 2016-13, Financial instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and subsequent related ASUs, which amends the guidance on the impairment of financial instruments by requiring measurement and recognition of expected credit losses for financial assets held. This ASU is effective for public and private companies’ fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, and December 15, 2022, respectively. As the Company is no longer an emerging growth company as of January 1, 2022, the Company plans to adopt ASU 2016-13 effective on such date, utilizing the modified retrospective transition method. The Company believes that adoption of ASU 2016-13 will not have a material impact on the Company’s consolidated financial statements.
In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. Under ASU 2021-08, an acquirer must recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. The guidance is effective for interim and annual periods beginning after December 15, 2022, with early adoption permitted. As indicated in Note 21 - Subsequent Events, the Company completed the acquisition of AlsoEnergy on February 1, 2022. Therefore, the Company plans to adopt ASU 2021-08 on a prospective basis effective January 1, 2022 and is currently assessing the effect, if any, the guidance will have on the Company's consolidated financial statements.
v3.22.0.1
REVENUE
 12 Months Ended
Dec. 31, 2021
Revenue from Contract with Customer [Abstract]  
REVENUE REVENUE
Disaggregation of Revenue
The following table provides information on the disaggregation of revenue as recorded in the consolidated statements of operations (in thousands):
Year ended December 31,
202120202019
Partnership hardware and service revenue
$107,135 $20,713 $4,076 
Host customer service revenue
20,236 15,594 13,476 
Total revenue
$127,371 $36,307 $17,552 
Remaining Performance Obligations
Remaining performance obligations represent contracted revenue that has not been recognized, which includes contract liabilities (deferred revenue) and amounts that will be billed and recognized as revenue in future periods. As of December 31, 2021, the Company had $217.8 million of remaining performance obligations, and the approximate percentages expected to be recognized as revenue in the future are as follows (in thousands, except percentages):
Total remaining
performance
obligations		Percent Expected to be Recognized as Revenue
Less than
one year		Two to
five years		Greater than
five years

Service revenue
$169,758 12 %50 %38 %
Hardware revenue
48,039 100 %— %— %
Total revenue$217,797 
Contract Balances
Deferred revenue primarily includes cash received in advance of revenue recognition related to energy optimization services and incentives. The following table presents the changes in the deferred revenue balance (in thousands):
202120202019
Beginning balance as of Beginning balance as of January 1,$52,410 $20,728$11,859
Upfront payments received from customers89,951 40,4816,698
Upfront or annual incentive payments received6,614 8,015 8,240 
Revenue recognized related to amounts that were included in beginning balance of deferred revenue(33,585)(9,764)(4,830)
Revenue recognized related to deferred revenue generated during the period(77,947)(7,050)(1,239)
Ending balance as of Ending balance as of December 31,$37,443 $52,410 $20,728 
v3.22.0.1
SHORT-TERM INVESTMENTS
 12 Months Ended
Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]  
SHORT-TERM INVESTMENTS SHORT-TERM INVESTMENTS
The following tables summarize the estimated fair value of the Company’s cash equivalents and debt securities and the gross unrealized holding gains and losses as of December 31, 2021 (in thousands):


Amortized costUnrealized gainUnrealized LossEstimated Fair Value
Assets
Cash equivalents:
Money market fund$127,261 $— $— $127,261 
Total cash equivalents$127,261 $— $— $127,261 
Debt securities:
Corporate debt securities$42,174 $11 $(52)$42,133 
Commercial paper20,743 — — 20,743 
U.S. government bonds86,265 — (135)86,130 
Certificate of deposits21,501 6 — 21,507 
Other2,500 — (5)2,495 
Total debt securities$173,183 $17 $(192)$173,008 
Classified as:
Cash equivalents$127,261 
Short-term debt securities173,008 
Long-term debt securities— 
The Company periodically reviews the available-for-sale securities for other-than-temporary impairment loss. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, it also considers whether (i) it is more likely than not that the Company will be required to sell the securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the year ended December 31, 2021, the Company did not recognize any other-than-temporary impairment losses. All securities with unrealized losses have been in a loss position for less than 12 months.
v3.22.0.1
FAIR VALUE MEASUREMENTS
 12 Months Ended
Dec. 31, 2021
Fair Value Disclosures [Abstract]  
FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS
Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. At December 31, 2021 and December 31, 2020, the carrying amount of accounts receivable, other current assets, accounts payable, and accrued and other current liabilities approximated their estimated fair value due to their relatively short maturities. There were no assets or liabilities classified as Level 3 as of December 31, 2021.
The following table provides the financial instruments measured at fair value on a recurring basis (in thousands):
December 31, 2021
Level 1Level 2Level 3Total
Assets
Cash equivalents:
Money market fund
$127,261$— $—$127,261
Debt securities
Corporate debt securities— 42,133 — 42,133
Commercial paper— 20,743 — 20,743
U.S. government bonds— 86,130 — 86,130
Certificate of deposits— 21,507 — 21,507
Other— 2,495 — 2,495 
Total financial assets$127,261 $173,008 $— $300,269 

December 31, 2020
Level 1Level 2Level 3Total
Assets
Cash equivalents:
Money market fund
$67 $— $— $67 
Liabilities
Convertible preferred stock warrant liability
$— $— $95,342 $95,342 
The Company’s money market funds are classified as Level 1 because they are valued using quoted market prices. The Company’s short-term investments consist of available-for-sale securities and are classified as Level 2 because their value is based on valuations using significant inputs derived from or corroborated by observable market data. The convertible preferred stock warrant liabilities are defined as Level 3 in the fair value hierarchy as the valuations are based on significant unobservable inputs, which reflect the Company’s own assumptions incorporated in valuation techniques used to determine fair value; further discussion of these assumptions is set forth below. There were no transfers into or out of Level 3 of the fair value hierarchy during the periods presented.

2028 Convertible Notes
In November 2021, the Company issued $460.0 million aggregate principal amount of its 2028 Convertible Notes. Upon issuance, the Company bifurcated the 2028 Convertible Notes for accounting purposes between a liability component and an equity component. The liability component was determined using a binomial lattice model by estimating the fair value of a hypothetical issuance of an identical offering excluding the conversion feature of the 2028 Convertible Notes. The initial carrying amount of the equity component was calculated as the difference between the liability component and the face value of the 2028 Convertible Senior Notes (See Note 12 - Convertible Promissory Notes). The estimated fair value of the 2028
Convertible Notes, which differs from their carrying value, is influenced by interest rates, the price of the Company’s common stock, the volatility, the expected term, and the prices for the notes observed in the market trading. The estimated fair value of the 2028 Convertible Notes, which are considered Level 2 financial instruments, was $324.8 million at issuance on November 22, 2021, and $447.8 million as of December 31, 2021.
Capped Call Options with respect to the 2028 Senior Notes
In connection with the issuance of the 2028 Convertible Notes, the Company entered into the capped call options with certain financial institutions. The capped calls cover 15,730,390 shares of common stock (subject to anti-dilution and certain other adjustments), which is the same number of shares of common stock that initially underlie the 2028 Convertible Notes. The Capped Calls have an initial strike price of approximately $29.2428 per share, which corresponds to the initial conversion price of the 2028 Convertible Notes, and have a cap price of approximately $49.6575 per share (See Note 12 - Convertible Promissory Notes). The strike price and cap price are subject to anti-dilution adjustments generally similar to those applicable to the 2028 Convertible Notes. These instruments meet certain accounting criteria to be classified in stockholders’ equity (deficit), and are not subsequently remeasured as long as the conditions for equity classification continue to be met.
Convertible Preferred Stock Warrant Liabilities
As discussed in Note 13 - Warrants, upon effectiveness of the Merger, substantially all of the outstanding convertible preferred stock warrants were converted into shares of common stock of Stem. As such, the associated warrant liability was reclassified to additional paid-in-capital upon the Merger and was no longer an outstanding Level 3 financial instrument as of December 31, 2021. The fair value of the convertible preferred stock warrants as of December 31, 2020 was determined using the Black-Scholes method as well as a discount for lack of marketability. Black-Scholes inputs used to value the warrants are based on information from purchase agreements and within valuation reports prepared by an independent third party for the Company. Inputs include exercise price, selection of guideline public companies, volatility, fair value of common or preferred stock, expected dividend rate and risk-free interest rate.
The key assumptions used for the valuation of the preferred stock warrant liabilities upon remeasurement were as follows:
Year Ended December 31, 2021
Volatility65.0 %
Risk-free interest rate0.1 %
Expected term (in years)1.5
Dividend yield— %
Discount for lack of marketability12.3 %
The following table presents the changes in the liability for the Company’s warrants during the years ended December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Balance as of January 1,
$95,342 $6,094 
Changes in estimated fair value488 85,623 
Assumption of warrant liability upon Merger302,556 — 
Issuance of warrants— 3,633 
Conversion of warrants upon Merger(60,568)— 
Exchange of warrants (168,647)— 
Exercise of warrants(169,171)(8)
Balance as of December 31,
$— $95,342 
v3.22.0.1
GOODWILL AND INTANGIBLE ASSETS, NET
 12 Months Ended
Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]  
GOODWILL AND INTANGIBLE ASSETS, NET GOODWILL AND INTANGIBLE ASSETS, NET
Goodwill
Goodwill consists of the following (in thousands):
December 31,
20212020
Goodwill$1,625 $1,625 
Effect of foreign currency translation116 114 
Total goodwill$1,741 $1,739 
Intangible Assets, Net
Intangible assets, net, consists of the following (in thousands):
December 31,
20212020
Developed technology$500 $500 
Internally developed software29,706 22,545 
Intangible assets30,206 23,045 
Less: Accumulated amortization(16,276)(10,993)
Add: Currency translation adjustment36 35 
Total intangible assets, net$13,966 $12,087 
Amortization expense for intangible assets was $5.3 million, $4.5 million and $3.1 million for the years ended December 31, 2021, 2020, and 2019, respectively, of which substantially all represents amortization of internally developed software recognized in cost of goods sold in the consolidated statements of operations.
v3.22.0.1
LEASES
 12 Months Ended
Dec. 31, 2021
Leases [Abstract]  
LEASES LEASES
The Company leases and subleases certain office spaces with lease terms ranging from 3 to 8 years. These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain of these leases also include renewal options at the election of the Company to renew or extend the lease for an additional five years. These optional periods have not been considered in the determination of the ROU assets or lease liabilities associated with these leases as the Company did not consider the exercise of these options to be reasonably certain.
The Company performed evaluations of its contracts and determined each of its identified leases are operating leases. For the years ended December 31, 2021, 2020, and 2019, the Company incurred $1.3 million, $0.8 million and $1.2 million, respectively, of rent expense included in operating expenses in the consolidated statements of operations in relation to its operating leases, inclusive of short-term and variable lease expense which was immaterial. Cash paid for amounts included in the measurement of operating lease liabilities for the years ended December 31, 2021, 2020, and 2019 was $0.5 million $0.7 million and $0.9 million, respectively, and was included in net cash used in operating activities in the Company’s consolidated statements of cash flows.
As of December 31, 2021, future payments associated with the Company’s operating lease liabilities were as follows (in thousands):
Operating
Leases
2022$1,818 
20232,473 
20242,239 
20252,109 
20262,172 
Thereafter4,937 
Total lease payments15,748 
Less: imputed interest(2,325)
Total operating lease liability future lease payments$13,423 
Reported as of December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Current portion of operating lease liabilities included within other current liabilities
$1,240 $333 
Non-current portion of operating lease liabilities12,183 57 
Total$13,423 $390 
The following summarizes additional information related to operating leases:
December 31,
20212020
Weighted average remaining operating lease term (in years)6.70.8
Weighted average discount rate4.5 %11.3 %
v3.22.0.1
ASSET RETIREMENT OBLIGATION
 12 Months Ended
Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]  
ASSET RETIREMENT OBLIGATION ASSET RETIREMENT OBLIGATION
The information below details the asset retirement obligation for the years ended December 31, 2021 and 2020 as follows (in thousands):
December 31,
20212020
Beginning balance at January 1,$4,137 $5,759 
Asset retirement obligation— 771 
Settlement of asset retirement obligation— (1,375)
Retirement cost revaluation(231)(1,235)
Accretion expense229 217 
Ending balance at December 31,$4,135 $4,137 
v3.22.0.1
ENERGY STORAGE SYSTEMS, NET
 12 Months Ended
Dec. 31, 2021
Property, Plant and Equipment [Abstract]  
ENERGY STORAGE SYSTEMS, NET ENERGY STORAGE SYSTEMS, NET
Energy Storage Systems, Net
Energy storage systems, net, consists of the following (in thousands):
December 31, 2021December 31, 2020
Energy storage systems placed into service$143,592 $144,425 
Less: accumulated depreciation(45,250)(33,389)
Energy storage systems not yet placed into service7,772 12,667 
Total energy storage systems, net$106,114 $123,703 
Depreciation expense for energy storage systems was approximately $14.4 million, $13.9 million and $9.7 million for the years ended December 31, 2021, 2020, and 2019, respectively. Depreciation expense is recognized in cost of service revenue.
v3.22.0.1
BALANCE SHEET COMPONENTS
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
BALANCE SHEET COMPONENTS BALANCE SHEET COMPONENTS
Inventory
Inventory consists of the following (in thousands):
December 31,
20212020
Work in process inventory$20,582 $15,296 
Batteries2,138 5,547 
Total inventory$22,720 $20,843 
Other Current Assets
Other current assets consist of the following (in thousands):
December 31,
20212020
Deferred costs with suppliers$13,744 $6,204 
Prepaid expenses3,137 698 
Utility program deposits353 891 
Due from related parties213 123 
Other1,194 4 
Total other current assets$18,641 $7,920 
Other Noncurrent Assets
Other noncurrent assets consist of the following (in thousands):
December 31,
20212020
Prepaid warranties and maintenance$15,991 $1,088 
Receivable from SPEs (Note 16)3,565 3,583 
Deferred SPAC costs— 1,256 
Self-generation incentive program deposits940 1,036 
Investment in VIEs1,924 744 
Revolver debt issuance costs— 73 
Property and equipment, net512 44 
Other1,599 458 
Total other noncurrent assets$24,531 $8,282 
Depreciation expense for property and equipment was immaterial for each of the years ended December 31, 2021, 2020 and 2019.
Accrued Liabilities
Accrued liabilities consist of the following (in thousands):
December 31,
20212020
Accrued payables$25,062 $9,799 
Accrued interest – notes payable344 6,149 
Other accrued liabilities587 124 
Total accrued liabilities$25,993 $16,072 
Other Current Liabilities
Other current liabilities consist of the following (in thousands):
December 31,
20212020
System advances$267 $640 
Lease liabilities – current portion1,240 333 
Due to related parties306 399 
Other— 217 
Total other current liabilities$1,813 $1,589 
v3.22.0.1
NOTES PAYABLE
 12 Months Ended
Dec. 31, 2021
Debt Disclosure [Abstract]  
NOTES PAYABLE NOTES PAYABLE
Revolving Loan Due to SPE Member
In April 2017, the Company entered into a revolving loan agreement with an affiliate of a member of certain of the Company’s special purpose entities (“SPE”). This agreement was, from time to time, subsequently amended. The purpose of this revolving loan agreement was to finance the Company’s purchase of hardware for its various energy storage system projects. The agreement had a total revolving loan capacity of $45.0 million that bore fixed interest at 10% with a maturity date of June 2020.
In May 2020, concurrent with the 2020 Credit Agreement discussed below, the Company entered into an amendment to the revolving loan agreement, which reduced the loan capacity to $35.0 million and extended the maturity date to May 2021. The amendment increased the fixed interest rate for any borrowings outstanding more than nine months to 14% thereafter. Additionally, under the original terms of the revolving loan agreement, the Company was able to finance 100% of the value of the hardware purchased up to the total loan capacity. The amendment reduced the advance rate to 85%, with an additional reduction to 70% in August 2020. The amendment was accounted for as a modification of the debt, which did not have a material impact on the consolidated financial statements. As of December 31, 2020, the Company had $7.4 million outstanding under the revolving loan agreement. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. The facility was terminated after the repayment in April 2021.
Term Loan Due to SPE Member
In December 2018, the Company entered into a term loan in the amount of $13.3 million with an affiliate of a member of certain SPEs with the Company. The term loan bore fixed interest of 12.5% on the outstanding principal balance with a final balloon payment of $3.0 million due at the maturity date of June 30, 2020. In May 2020, the Company repaid the remaining outstanding balance of $5.9 million with the proceeds received through the 2020 Credit Agreement discussed below.
Term Loan Due to Former Non-Controlling Interest Holder
In June 2018, the Company acquired the outstanding member interests of an entity controlled by the Company for $8.1 million. The Company financed this acquisition by entering into a term loan agreement with the noncontrolling member bearing fixed interest of 4.5% per quarter (18.0% per annum) on the outstanding principal balance. The loan required fixed quarterly payments throughout the term of the loan, which was scheduled to be paid in full by April 1, 2026.
In May 2020, the Company amended the term loan and, using the proceeds from the 2020 Credit Agreement discussed below, prepaid $1.5 million of principal and interest on the note, of which $1.0 million was towards the outstanding principal balance, thereby reducing the fixed quarterly payment due to the lender. In relation to this amendment, the Company was required to issue warrants for 400,000 shares of common stock resulting in a discount to the term loan of $0.2 million. As of December 31, 2020, the outstanding balance was $5.8 million. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. Upon prepayment of this facility, the Company incurred $2.6 million in prepayment penalties that were recorded to loss on extinguishment of debt in the Company’s statement of operations. The facility was terminated after the repayment in April 2021.
2020 Credit Agreement
In May 2020, the Company entered into a credit agreement (“2020 Credit Agreement”) with a new lender that provided the Company with proceeds of $25.0 million to provide the Company with access to working capital towards the purchase of energy storage system equipment. The 2020 Credit Agreement has a maturity date of the earlier of (1) May 2021, (2) the maturity date of the revolving loan agreement, or (3) the maturity date of the Pre-Merger Convertible Promissory Notes discussed below in Note 12 - Convertible Promissory Notes. The loan bore interest of 12% per annum, of which 8% was paid in cash and 4% added back to principal of the loan balance every quarter. The Company used a portion of the proceeds towards payments associated with existing debt as previously discussed. As of December 31, 2020, the outstanding balance was $25.6 million. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. Upon prepayment of this facility, the Company incurred $1.4 million in prepayment penalties that were recorded to loss on extinguishment of debt in the Company’s statement of operations. The facility was terminated after the repayment in April 2021.
2021 Credit Agreement
In January 2021, the Company, through a wholly owned Canadian entity, entered into a credit agreement to provide a total of $2.7 million towards the financing of certain energy storage systems. The credit agreement is structured on a non-recourse basis and the system will be operated by the Company. The credit agreement has a stated interest of 5.45% and a maturity date of June 2031. The Company received an advance under the credit agreement of $1.8 million in January 2021. The repayment of advances received under this credit agreement is determined by the lender based on the proceeds generated by the Company through the operation of the underlying energy storage systems. As of December 31, 2021, the outstanding balance was $1.9 million. The Company was in compliance with all covenants contained in the 2021 Credit Agreement as of December 31, 2021.
The Company’s outstanding debt consisted of the following as of December 31, 2021 (in thousands):
December 31, 2021
Outstanding principal$1,902 
Unamortized discount(215)
Carrying value of debt$1,687 
CONVERTIBLE PROMISSORY NOTES
As of December 31, 2020, the Company had various convertible notes outstanding to investors. The Company refers to the collective group of all such note instruments as the “Pre-Merger Convertible Promissory Notes.” As of December 31, 2020, these Pre-Merger Convertible Promissory Notes had a balance of $67.6 million. During the year ended December 31, 2021, the Company issued additional convertible notes, including convertible promissory notes issued and sold in January 2021 (the “Q1 2021 Convertible Notes”) and the 2028 Convertible Notes. Upon effectiveness of the Merger on April 28, 2021, all outstanding Pre-Merger Convertible Promissory Notes were converted to common stock and cancelled (see “—Conversion and Cancellation of Convertible Promissory Notes Upon Merger” below). As of December 31, 2021, the Pre-Merger Convertible Promissory Notes and the Q1 2021 Convertible Notes were no longer outstanding.

Q1 2021 Convertible Notes
In January 2021, the Company issued and sold the Q1 2021 Convertible Notes under the same terms as the then existing Pre-Merger Convertible Promissory Notes to various investors with aggregate gross proceeds of $1.1 million. The Company evaluated the conversion option within the Q1 2021 Convertible Notes and determined the effective conversion price was beneficial to the note holders.
Conversion and Cancellation of Convertible Promissory Notes Upon Merger
Immediately prior to the effectiveness of the Merger, the entire balance of the Company’s outstanding Pre-Merger Convertible Promissory Notes issued by Legacy Stem automatically converted into shares of Legacy Stem Common Stock. Upon the effectiveness of the Merger, these shares of Legacy Stem Common Stock automatically converted into 10,921,548 shares of common stock of Stem. The balance associated with the outstanding Pre-Merger Convertible Promissory Notes totaling $77.7 million, including $7.7 million of interest accrued on the notes through the date of Merger, was reclassified to additional paid-in-capital. The unamortized portion of the debt discount associated with the outstanding Q1 2021 Convertible Notes totaling $1.1 million was fully expensed to loss on extinguishment of debt on the Company’s statement of operations.
2028 Convertible Notes and Capped Call Options
2028 Convertible Notes
On November 22, 2021, the Company issued $460.0 million aggregate principal amount of its 2028 Convertible Notes in a private placement offering to qualified institutional buyers (the “Initial Purchasers”) pursuant to Rule 144A under the Securities Act of 1933, as amended.
The 2028 Convertible Notes are senior, unsecured obligations of the Company and bear interest at a rate of 0.5% per year, payable in cash semi-annually in arrears in June and December of each year, beginning in June 2022. The notes will mature on December 1, 2028, unless earlier repurchased, redeemed or converted in accordance with their terms prior to such date. Upon conversion, the Company may choose to pay or deliver, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock. The Notes are redeemable for cash at the Company’s option at any time given certain conditions (as discussed below), at an initial conversion rate of 34.1965 shares of common stock per $1,000 principal amount of 2028 Convertible Notes, which is equivalent to an initial conversion price of approximately $29.24 (the “2028 Conversion Price”) per share of the Company’s common stock. The conversion rate is subject to customary adjustments for certain events as described in the Indenture.
The Company may redeem for cash all or any portion of the 2028 Convertible Notes, at the Company’s option, on or after December 5, 2025 if the last reported sale price of the Company’s common stock has been at least 130% of the 2028 Conversion Price then in effect for at least 20 trading days at a redemption price equal to 100% of the principal amount of the 2028 Convertible Notes to be redeemed, plus accrued and unpaid interest.
The Company’s net proceeds from this offering were approximately $445.7 million, after deducting the Initial Purchasers’ discounts and debt issuance costs. To minimize the impact of potential dilution to the Company’s common stockholders upon
conversion of the 2028 Convertible Notes, the Company entered into separate capped calls transactions (the “Capped Calls”) as described below.
In accordance with accounting guidance for debt with conversion and other options, the Company separately accounted for the liability and equity components of the 2028 Convertible Notes by allocating the proceeds between the liability component and the equity component, due to the Company's ability to settle the 2028 Convertible Notes in cash, its common Stock, or a combination of cash and common Stock at the option of the Company. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated conversion feature. The equity component of the 2028 Convertible Notes was recognized as a debt discount and represents the difference between the gross proceeds from the issuance of the 2028 Convertible Notes and the fair value of the liability component of the 2028 Convertible Notes on the date of issuance. The debt discount is amortized to interest expense using the effective interest method over approximately seven years, or the expected life of the 2028 Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification.
After allocating the proceeds of the liability and equity components, the Company further allocated $14.3 million initial purchasers’ debt discount and debt issuance cost of $12.4 million and $1.9 million, respectively. The initial purchaser’s discount and debt issuance costs primarily consisted of underwriters, advisory, legal, and accounting fees. These costs were allocated to the debt and equity components based on the allocation of the proceeds as follows (in thousands):
AmountEquity ComponentDebt Component
Initial Purchaser’s Debt Discount$12,420 $3,650 $8,770 
Debt Issuance Costs1,871 550 1,321 
Total$14,291 $4,200 $10,091 
The portion allocated to the debt component is amortized to interest expense using the effective interest method over the expected life of the 2028 Convertible Notes, or approximately its seven-year term. The effective interest rate on the liability component of the 2028 Convertible Notes for the period from the date of issuance through December 2028 is 5.96%, which remains unchanged from the date of issuance.
The outstanding 2028 Convertible Notes balances as of December 31, 2021, are summarized in the following table (in thousands):
December 31, 2021
Debt Component
Outstanding principal$460,000 
Unamortized initial purchaser’s debt discount and debt issuance cost(143,458)
Net carrying amount$316,542 
At the original issuance date, the fair value of the debt component of the Company’s 2028 Convertible Notes was $324.8 million and the estimated fair value of the equity component was $135.2 million, as measured on the date of issuance, resulting in a total fair value of $460.0 million for the 2028 Convertible Notes. The 2028 Convertible Notes were priced at par at the valuation date resulting in the fair value of the 2028 Convertible Notes equal to the principal amount of $460.0 million. The fair value of the equity component has been calculated as the residual amount between the fair value of the 2028 Convertible Notes and the fair value of the debt component.
The following table presents total interest expense recognized related to the 2028 Convertible Notes during the year ended December 31, 2021 (in thousands):
December 31, 2021
Cash interest expense
Contractual interest expense$249 
Non-cash interest expense
Amortization of debt discount and debt issuance cost$1,812 
Total interest expense$2,061 
Capped Call Options
On November 17, 2021, in connection with the pricing of the 2028 Convertible Notes, and on November 19, 2021, in connection with the exercise in full by the Initial Purchasers of their option to purchase additional Notes, the Company entered into Capped Calls with certain counterparties. The Company used $66.7 million of the net proceeds to pay the cost of the Capped Calls.
The Capped Calls have an initial strike price of $29.2428 per share, which corresponds to the initial conversion price of the 2028 Convertible Notes and is subject to anti-dilution adjustments. The Capped Calls have a cap price of $49.6575 per share, subject to certain adjustments.
The Capped Calls are considered separate transactions entered into by and between the Company and the Capped Calls counterparties, and are not part of the terms of the 2028 Convertible Notes. The Company recorded a reduction to additional paid-in capital of $66.7 million during the year ended December 31, 2021 related to the premium payments for the Capped Calls. These instruments meet the conditions outlined in ASC 815 to be classified in stockholders’ equity (deficit) and are not subsequently remeasured as long as the conditions for equity classification continue to be met.
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CONVERTIBLE PROMISSORY NOTES
 12 Months Ended
Dec. 31, 2021
Debt Disclosure [Abstract]  
CONVERTIBLE PROMISSORY NOTES NOTES PAYABLE
Revolving Loan Due to SPE Member
In April 2017, the Company entered into a revolving loan agreement with an affiliate of a member of certain of the Company’s special purpose entities (“SPE”). This agreement was, from time to time, subsequently amended. The purpose of this revolving loan agreement was to finance the Company’s purchase of hardware for its various energy storage system projects. The agreement had a total revolving loan capacity of $45.0 million that bore fixed interest at 10% with a maturity date of June 2020.
In May 2020, concurrent with the 2020 Credit Agreement discussed below, the Company entered into an amendment to the revolving loan agreement, which reduced the loan capacity to $35.0 million and extended the maturity date to May 2021. The amendment increased the fixed interest rate for any borrowings outstanding more than nine months to 14% thereafter. Additionally, under the original terms of the revolving loan agreement, the Company was able to finance 100% of the value of the hardware purchased up to the total loan capacity. The amendment reduced the advance rate to 85%, with an additional reduction to 70% in August 2020. The amendment was accounted for as a modification of the debt, which did not have a material impact on the consolidated financial statements. As of December 31, 2020, the Company had $7.4 million outstanding under the revolving loan agreement. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. The facility was terminated after the repayment in April 2021.
Term Loan Due to SPE Member
In December 2018, the Company entered into a term loan in the amount of $13.3 million with an affiliate of a member of certain SPEs with the Company. The term loan bore fixed interest of 12.5% on the outstanding principal balance with a final balloon payment of $3.0 million due at the maturity date of June 30, 2020. In May 2020, the Company repaid the remaining outstanding balance of $5.9 million with the proceeds received through the 2020 Credit Agreement discussed below.
Term Loan Due to Former Non-Controlling Interest Holder
In June 2018, the Company acquired the outstanding member interests of an entity controlled by the Company for $8.1 million. The Company financed this acquisition by entering into a term loan agreement with the noncontrolling member bearing fixed interest of 4.5% per quarter (18.0% per annum) on the outstanding principal balance. The loan required fixed quarterly payments throughout the term of the loan, which was scheduled to be paid in full by April 1, 2026.
In May 2020, the Company amended the term loan and, using the proceeds from the 2020 Credit Agreement discussed below, prepaid $1.5 million of principal and interest on the note, of which $1.0 million was towards the outstanding principal balance, thereby reducing the fixed quarterly payment due to the lender. In relation to this amendment, the Company was required to issue warrants for 400,000 shares of common stock resulting in a discount to the term loan of $0.2 million. As of December 31, 2020, the outstanding balance was $5.8 million. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. Upon prepayment of this facility, the Company incurred $2.6 million in prepayment penalties that were recorded to loss on extinguishment of debt in the Company’s statement of operations. The facility was terminated after the repayment in April 2021.
2020 Credit Agreement
In May 2020, the Company entered into a credit agreement (“2020 Credit Agreement”) with a new lender that provided the Company with proceeds of $25.0 million to provide the Company with access to working capital towards the purchase of energy storage system equipment. The 2020 Credit Agreement has a maturity date of the earlier of (1) May 2021, (2) the maturity date of the revolving loan agreement, or (3) the maturity date of the Pre-Merger Convertible Promissory Notes discussed below in Note 12 - Convertible Promissory Notes. The loan bore interest of 12% per annum, of which 8% was paid in cash and 4% added back to principal of the loan balance every quarter. The Company used a portion of the proceeds towards payments associated with existing debt as previously discussed. As of December 31, 2020, the outstanding balance was $25.6 million. In April 2021, the Company repaid the remaining outstanding balance of this facility with the proceeds received from the Merger. Upon prepayment of this facility, the Company incurred $1.4 million in prepayment penalties that were recorded to loss on extinguishment of debt in the Company’s statement of operations. The facility was terminated after the repayment in April 2021.
2021 Credit Agreement
In January 2021, the Company, through a wholly owned Canadian entity, entered into a credit agreement to provide a total of $2.7 million towards the financing of certain energy storage systems. The credit agreement is structured on a non-recourse basis and the system will be operated by the Company. The credit agreement has a stated interest of 5.45% and a maturity date of June 2031. The Company received an advance under the credit agreement of $1.8 million in January 2021. The repayment of advances received under this credit agreement is determined by the lender based on the proceeds generated by the Company through the operation of the underlying energy storage systems. As of December 31, 2021, the outstanding balance was $1.9 million. The Company was in compliance with all covenants contained in the 2021 Credit Agreement as of December 31, 2021.
The Company’s outstanding debt consisted of the following as of December 31, 2021 (in thousands):
December 31, 2021
Outstanding principal$1,902 
Unamortized discount(215)
Carrying value of debt$1,687 
CONVERTIBLE PROMISSORY NOTES
As of December 31, 2020, the Company had various convertible notes outstanding to investors. The Company refers to the collective group of all such note instruments as the “Pre-Merger Convertible Promissory Notes.” As of December 31, 2020, these Pre-Merger Convertible Promissory Notes had a balance of $67.6 million. During the year ended December 31, 2021, the Company issued additional convertible notes, including convertible promissory notes issued and sold in January 2021 (the “Q1 2021 Convertible Notes”) and the 2028 Convertible Notes. Upon effectiveness of the Merger on April 28, 2021, all outstanding Pre-Merger Convertible Promissory Notes were converted to common stock and cancelled (see “—Conversion and Cancellation of Convertible Promissory Notes Upon Merger” below). As of December 31, 2021, the Pre-Merger Convertible Promissory Notes and the Q1 2021 Convertible Notes were no longer outstanding.

Q1 2021 Convertible Notes
In January 2021, the Company issued and sold the Q1 2021 Convertible Notes under the same terms as the then existing Pre-Merger Convertible Promissory Notes to various investors with aggregate gross proceeds of $1.1 million. The Company evaluated the conversion option within the Q1 2021 Convertible Notes and determined the effective conversion price was beneficial to the note holders.
Conversion and Cancellation of Convertible Promissory Notes Upon Merger
Immediately prior to the effectiveness of the Merger, the entire balance of the Company’s outstanding Pre-Merger Convertible Promissory Notes issued by Legacy Stem automatically converted into shares of Legacy Stem Common Stock. Upon the effectiveness of the Merger, these shares of Legacy Stem Common Stock automatically converted into 10,921,548 shares of common stock of Stem. The balance associated with the outstanding Pre-Merger Convertible Promissory Notes totaling $77.7 million, including $7.7 million of interest accrued on the notes through the date of Merger, was reclassified to additional paid-in-capital. The unamortized portion of the debt discount associated with the outstanding Q1 2021 Convertible Notes totaling $1.1 million was fully expensed to loss on extinguishment of debt on the Company’s statement of operations.
2028 Convertible Notes and Capped Call Options
2028 Convertible Notes
On November 22, 2021, the Company issued $460.0 million aggregate principal amount of its 2028 Convertible Notes in a private placement offering to qualified institutional buyers (the “Initial Purchasers”) pursuant to Rule 144A under the Securities Act of 1933, as amended.
The 2028 Convertible Notes are senior, unsecured obligations of the Company and bear interest at a rate of 0.5% per year, payable in cash semi-annually in arrears in June and December of each year, beginning in June 2022. The notes will mature on December 1, 2028, unless earlier repurchased, redeemed or converted in accordance with their terms prior to such date. Upon conversion, the Company may choose to pay or deliver, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock. The Notes are redeemable for cash at the Company’s option at any time given certain conditions (as discussed below), at an initial conversion rate of 34.1965 shares of common stock per $1,000 principal amount of 2028 Convertible Notes, which is equivalent to an initial conversion price of approximately $29.24 (the “2028 Conversion Price”) per share of the Company’s common stock. The conversion rate is subject to customary adjustments for certain events as described in the Indenture.
The Company may redeem for cash all or any portion of the 2028 Convertible Notes, at the Company’s option, on or after December 5, 2025 if the last reported sale price of the Company’s common stock has been at least 130% of the 2028 Conversion Price then in effect for at least 20 trading days at a redemption price equal to 100% of the principal amount of the 2028 Convertible Notes to be redeemed, plus accrued and unpaid interest.
The Company’s net proceeds from this offering were approximately $445.7 million, after deducting the Initial Purchasers’ discounts and debt issuance costs. To minimize the impact of potential dilution to the Company’s common stockholders upon
conversion of the 2028 Convertible Notes, the Company entered into separate capped calls transactions (the “Capped Calls”) as described below.
In accordance with accounting guidance for debt with conversion and other options, the Company separately accounted for the liability and equity components of the 2028 Convertible Notes by allocating the proceeds between the liability component and the equity component, due to the Company's ability to settle the 2028 Convertible Notes in cash, its common Stock, or a combination of cash and common Stock at the option of the Company. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated conversion feature. The equity component of the 2028 Convertible Notes was recognized as a debt discount and represents the difference between the gross proceeds from the issuance of the 2028 Convertible Notes and the fair value of the liability component of the 2028 Convertible Notes on the date of issuance. The debt discount is amortized to interest expense using the effective interest method over approximately seven years, or the expected life of the 2028 Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification.
After allocating the proceeds of the liability and equity components, the Company further allocated $14.3 million initial purchasers’ debt discount and debt issuance cost of $12.4 million and $1.9 million, respectively. The initial purchaser’s discount and debt issuance costs primarily consisted of underwriters, advisory, legal, and accounting fees. These costs were allocated to the debt and equity components based on the allocation of the proceeds as follows (in thousands):
AmountEquity ComponentDebt Component
Initial Purchaser’s Debt Discount$12,420 $3,650 $8,770 
Debt Issuance Costs1,871 550 1,321 
Total$14,291 $4,200 $10,091 
The portion allocated to the debt component is amortized to interest expense using the effective interest method over the expected life of the 2028 Convertible Notes, or approximately its seven-year term. The effective interest rate on the liability component of the 2028 Convertible Notes for the period from the date of issuance through December 2028 is 5.96%, which remains unchanged from the date of issuance.
The outstanding 2028 Convertible Notes balances as of December 31, 2021, are summarized in the following table (in thousands):
December 31, 2021
Debt Component
Outstanding principal$460,000 
Unamortized initial purchaser’s debt discount and debt issuance cost(143,458)
Net carrying amount$316,542 
At the original issuance date, the fair value of the debt component of the Company’s 2028 Convertible Notes was $324.8 million and the estimated fair value of the equity component was $135.2 million, as measured on the date of issuance, resulting in a total fair value of $460.0 million for the 2028 Convertible Notes. The 2028 Convertible Notes were priced at par at the valuation date resulting in the fair value of the 2028 Convertible Notes equal to the principal amount of $460.0 million. The fair value of the equity component has been calculated as the residual amount between the fair value of the 2028 Convertible Notes and the fair value of the debt component.
The following table presents total interest expense recognized related to the 2028 Convertible Notes during the year ended December 31, 2021 (in thousands):
December 31, 2021
Cash interest expense
Contractual interest expense$249 
Non-cash interest expense
Amortization of debt discount and debt issuance cost$1,812 
Total interest expense$2,061 
Capped Call Options
On November 17, 2021, in connection with the pricing of the 2028 Convertible Notes, and on November 19, 2021, in connection with the exercise in full by the Initial Purchasers of their option to purchase additional Notes, the Company entered into Capped Calls with certain counterparties. The Company used $66.7 million of the net proceeds to pay the cost of the Capped Calls.
The Capped Calls have an initial strike price of $29.2428 per share, which corresponds to the initial conversion price of the 2028 Convertible Notes and is subject to anti-dilution adjustments. The Capped Calls have a cap price of $49.6575 per share, subject to certain adjustments.
The Capped Calls are considered separate transactions entered into by and between the Company and the Capped Calls counterparties, and are not part of the terms of the 2028 Convertible Notes. The Company recorded a reduction to additional paid-in capital of $66.7 million during the year ended December 31, 2021 related to the premium payments for the Capped Calls. These instruments meet the conditions outlined in ASC 815 to be classified in stockholders’ equity (deficit) and are not subsequently remeasured as long as the conditions for equity classification continue to be met.
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WARRANTS
 12 Months Ended
Dec. 31, 2021
Equity [Abstract]  
WARRANTS WARRANTS
Legacy Stem Warrants
Since inception the Company has issued warrants to purchase shares of Legacy Stem’s preferred stock in conjunction with various debt financings. See Note 5 - Fair Value Measurements, for further information regarding fair value measurements associated with the resulting warrant liabilities, which are remeasured on a recurring basis each period. The Company has also issued warrants to purchase shares of Legacy Stem’s common stock. Upon effectiveness of the Merger, the Company had 50,207,439 warrants outstanding, of which substantially all were converted into 2,759,970 shares of common stock of Stem. Upon conversion of the warrants, the existing warrant liabilities were remeasured to fair value resulting in a gain on remeasurement of $100.9 million and a total warrant liability of $60.6 million, which was then reclassified to additional paid-in-capital. As of December 31, 2021, there were 23,673 Legacy Stem Warrants outstanding. These instruments are exercisable into the Company’s common stock and are equity classified.
Public Warrants and Private Placement Warrants
As part of STPK’s initial public offering, under the Warrant Agreement dated as of August 20, 2020 (the “Warrant Agreement”) and, prior to the effectiveness of the Merger, STPK issued 12,786,168 warrants each of which entitled the holder to purchase one share of common stock at an exercise price of $11.50 per share of common stock (the “Public Warrants”). Simultaneously with the closing of the Initial Public Offering, STPK completed the private sale of 7,181,134 million warrants to STPK’s sponsor (the “Private Warrants”). Upon issuance, these warrants met the criteria for liability classification. Upon the effectiveness of the Merger, Stem assumed the outstanding Public Warrants and Private Warrants, which continued to meet the criteria for liability classification, resulting in assumed warrant liabilities of $185.9 million and $116.7 million, respectively, or a total warrant liability of $302.6 million. Such warrants were initially recorded at fair value and remeasured to fair value at each reporting period. The fair value of the Private Warrants was determined using the Black-Scholes method as well as a discount for lack of marketability. Black-Scholes inputs used to value the warrants are based on information from purchase agreements and within valuation reports prepared by an independent third party for the Company. Inputs include exercise price, selection of guideline public companies, volatility, fair value of common stock, expected dividend rate and risk-free interest rate.
On June 25, 2021, the Company entered into an exchange agreement (the “Exchange Agreement”) with the holders of the 7,181,134 outstanding Private Placement Warrants, pursuant to which such holders received 4,683,349 shares of the Company’s common stock on June 30, 2021, in exchange for the cancellation of the outstanding Private Placement Warrants. The
Exchange Shares were issued in reliance upon the exemption provided by Section 3(a)(9) of the Securities Act of 1933, as amended. Immediately prior to the exchange, the Private Warrants were marked to fair value, resulting in a loss of $52.0 million. As a result of the Exchange Agreement, there were no Private Warrants outstanding as of December 31, 2021.
On August 20, 2021, the Company issued an irrevocable notice for redemption of all 12,786,129 of the Company’s outstanding public warrants at 5:00 p.m. Eastern time on September 20, 2021 (“Redemption Date”). Pursuant to the notice of redemption, holders exercised 12,638,723 Public Warrants for a purchase price of $11.50 per share, for proceeds to the Company of approximately $145.3 million. The Company redeemed all remaining outstanding Public Warrants that had not been exercised as of 5:00 p.m. Eastern time on the Redemption Date. As a result of the settlement of the Public Warrants, the Company recorded a gain of $134.9 million on the revaluation of the warrant liability. The Company also recorded a gain of $2.1 million on the redemption of unexercised public warrants. These gains are recorded in “change in fair value of warrants and embedded derivative” in the consolidated statements of operation in the year ended December 31, 2021. The public warrants have been delisted from the NYSE, and there are no public warrants left outstanding.
Warrants Issued for Services
On April 7, 2021, the Company entered into a strategic relationship with an existing shareholder not deemed to be a related party to jointly explore on a non-exclusive basis possible business opportunities to advance projects in the United States, the United Kingdom, Europe and Asia. As consideration for the strategic relationship, upon closing of the Merger, the Company issued warrants to purchase 350,000 shares of the Company’s common stock at an exercise price of $0.01 per share. These warrants were deemed to have been fully earned as of the grant date. The warrants were valued at fair market value as of the grant date totaling $9.2 million and recorded to general and administrative expense in the Company’s statement of operations. In May 2021, all of these warrants were exercised for shares of the Company’s common stock.
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COMMON STOCK
 12 Months Ended
Dec. 31, 2021
Equity [Abstract]  
COMMON STOCK COMMON STOCKThe Company had reserved shares of common stock for issuance as follows:
December 31,
2021
Shares reserved for warrants23,673
Options issued and outstanding8,766,466
Shares available for future issuance under equity incentive plan20,844,788
Conversion of 2028 Convertible Notes20,842,773
Total 50,477,700
As of December 31, 2021, the Company had 23,722,254 shares of common stock reserved for future issuance under equity incentive plans corresponding to the 2021 Equity Incentive Plan. As of December 31, 2021, 1,075,635 stock options and 1,801,831 RSUs had been granted to employees under the 2021 Equity Incentive Plan.
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STOCK-BASED COMPENSATION
 12 Months Ended
Dec. 31, 2021
Share-based Payment Arrangement [Abstract]  
STOCK-BASED COMPENSATION STOCK-BASED COMPENSATION
Under both the Stem, Inc. 2009 Equity Incentive Plan (the “2009 Plan”) and the Stem Inc. 2021 Equity Incentive Plan (the “2021 Plan,” and together with the 2009 Plan, the “Plans”), the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units (“RSUs”) and other awards that are settled in shares of the Company’s common stock. The Plans permit net settlement of vested awards, pursuant to which the award holder forfeits a portion of the vested award to satisfy the purchase price (in the case of stock options), the holder’s withholding tax obligation, if any, or both. When the holder net settles the tax obligation, the Company pays the amount of the withholding tax to the U.S. government in cash, which is accounted for as an adjustment to additional paid-in-capital. The Company does not intend to grant new awards under the 2009 Plan. At December 31, 2021, 7,754,811 stock options were outstanding under the 2009 Plan. In May 2021, the Company began issuing awards under the 2021 Plan, with 23,722,254 shares reserved thereunder.

Stock Options
Under the Plans, the exercise price of an option cannot be less than 100% of the fair value of one share of common stock for incentive or non-qualified stock options, and not less than 110% of the fair value for stockholders owning greater than 10% of all classes of stock, as determined by the Company’s Board of Directors (the “Board”). Options under the Plans generally expire after 10 years. Under the Plans, the Compensation Committee of the Board determines when the options granted will become exercisable. Options granted under the Plans generally vest 1/4 one year from the grant date and then 1/48 each month
over the following three years and are exercisable for 10 years from the date of the grant. The Plans allow for exercise of unvested options with repurchase rights over the restricted common stock issued at the original exercise price. The repurchase rights lapse at the same rate as the options vest.
The following table summarizes the stock option activity for the period ended December 31, 2021:
Number of
Options
Outstanding		Weighted-
Average
Exercise Price
Per Share		Weighted-
Average
Remaining
Contractual
Life (years)		Aggregate
Intrinsic
Value
(in thousands)
Balances as of December 31, 202051,379,939 $0.56 7.2$46,516 
Retroactive application of recapitalization(40,314,281)2.05 —— 
Adjusted Balance as of December 31, 202011,065,658 2.61 7.246,516 
Options granted1,079,583 28.73 
Options exercised(3,235,713)1.64 
Options forfeited(129,102)15.18 
Options expired(13,960)0.53
Balances as of December 31, 20218,766,466 $6.01 7.1$123,570 
Options vested and exercisable — December 31, 20216,298,675 $2.61 6.4$103,100 
The weighted-average grant date fair value of stock options granted to employees was $18.84, $3.79 and $1.58 during the years ended December 31, 2021, 2020, and 2019, respectively. The intrinsic value of options exercised was $56.1 million, $1.1 million and less than $0.1 million during the years ended December 31, 2021, 2020, and 2019, respectively. During the year ended December 31, 2021, the Company issued 1,054,594 shares of common stock from the net settlement of 1,648,463 stock options and shares granted. The Company paid $12.6 million in withholding taxes in connection with the net share settlement of these awards.

Significant Assumptions in Estimating Option Fair Value
The Company uses the Black-Scholes model for estimating the fair value of options granted. The weighted-average assumptions used in the Black-Scholes are as follows:
December 31,
202120202019
Expected volatility74.00 %71.41 %69.10 %
Risk-free interest rate1.06 %0.49 %2.47 %
Expected term (years)6.235.825.83
Dividend yield———
Restricted Stock Units
RSUs represent a right to receive one share of the Company’s common stock that is both non-transferable and forfeitable unless and until certain conditions are satisfied. RSUs generally, either cliff vest on the third anniversary of the award grant date, or vest 1/4 per year over a four-year period, subject to continued employment through each anniversary. During the year ended December 31, 2021, the Company granted RSUs, which vest 1/5 per year over approximately a seven-year period starting in April 2024. The fair value of restricted stock units is determined on the grant date and is amortized over the vesting period on a straight-line basis.
The following table summarizes the RSU activity for the period ended December 31, 2021:
Number of
RSUs
Outstanding		Weighted-
Average
Grant Date Fair Value
Per Share
Balances as of December 31, 2020—$— 
RSUs granted1,801,83136.0 
RSUs vested—— 
RSUs forfeited(2,154)26.1 
Balances as of December 31, 20211,799,67736.0 
The fair value of all RSUs granted during the year ended December 31, 2021 was $64.8 million. During the year ended December 31, 2021, no RSUs vested.

Stock-Based Compensation Expense
The following table summarizes stock-based compensation expense recorded in each component of operating expenses in the Company’s consolidated statements of operations and comprehensive loss (in thousands):
Year Ended December 31,
202120202019
Sales and marketing$1,723 $396 $364 
Research and development2,367 1,211 901 
General and administrative9,456 2,935 266 
Total stock-based compensation expense$13,546 $4,542 $1,531 
As of December 31, 2021, the Company had approximately $21.1 million of remaining unrecognized stock-based compensation expense for stock options, which is expected to be recognized over a weighted average period of 3.2 years. As of December 31, 2021, the Company had approximately $56.5 million of remaining unrecognized stock-based compensation expense for RSUs, which is expected to be recognized over a weighted average period of 4.9 years. Research and development expenses of $1.2 million corresponding to internal-use software, were capitalized during the year ended December 31, 2021.
v3.22.0.1
SPECIAL PURPOSE ENTITIES
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
SPECIAL PURPOSE ENTITIES SPECIAL PURPOSE ENTITIES
The Company has formed various SPEs to finance the development and construction of its energy storage systems. These SPEs, which are structured as limited liability companies, obtain financing from outside investors and purchase projects from the Company under master purchase agreements by making an upfront payment to the Company for such energy storage systems. As discussed in Note 2 - Summary of Significant Accounting Policies, the Company accounts for the large upfront payment received from the SPE as a financing obligation. The legal purchase of the energy storage system does not affect the Company’s legal or constructive obligation to the host customer.
Consolidated VIE
In September 2013, the Company entered into agreements to form SCF 1, LLC (“SCF 1”) and consolidated this SPE under the VIE consolidation model. During 2018, the Company acquired the outstanding non-controlling interests of SCF 1 which remained a VIE upon reconsideration at the acquisition.
As of December 31, 2021 and 2020, the Company’s consolidated total assets include the assets of SCF 1 that can only be used to settle the liabilities, if any, of SCF 1. The assets and liabilities of SCF 1 are comprised primarily of the following:
December 31,
20212020
Energy storage systems, net$649 $1,463 
Deferred revenue, current$283 $283 
Deferred revenue, noncurrent$753 $1,047 
Other liabilities$159 $239 
Unconsolidated VIEs
SPV II, SPV III, and SPV IV
On January 23, 2015, June 7, 2016, and June 30, 2017 the Company entered into agreements to form three Limited Liability Companies: Stem Finance SPV II, LLC (“SPV II”), Stem Finance SPV III, LLC (“SPV III”), and Generate-Stem LCR, LLC (“SPV IV”), respectively. These agreements are accounted for as unconsolidated VIEs because the Company lacks the power to direct the activities that most significantly impact the economics of these entities. Although the Company is not the primary beneficiary of these entities, due to its significant continuing involvement in the generation of cash flows of the energy storage systems and legal responsibilities under the host customer contract, the Company is required to include the assets, liabilities, revenues, and expenses of these entities in its consolidated financial statements. The significant activities involve deciding which energy storage systems to be purchased by the SPE and setting of the annual operating budgets which govern the ongoing operation and maintenance of the energy storage systems. Both of these activities significantly impact the revenue, expenses, and resulting residual returns or losses that will accrue to the investors of the SPE and require approval by both Stem and the other third-party investor. Stem, the non-managing member of the SPE, shares power through its rights to (i) agree on SPE purchases of energy storage systems in the master purchase agreement, and (ii) approve the annual operating budgets in the operating and maintenance agreement. The other investor shares power through its rights as the managing member in the SPE. As a result, power is shared with the other investors in the SPE who are not considered related parties (including de facto agency relationships) of the Company. Investments in such SPEs are accounted for under the equity method of accounting and are recorded within other noncurrent assets on the consolidated balance sheets. The Company’s maximum loss exposure from these entities is limited to the aggregate carrying amount of its equity method investments. As of December 31, 2021, the Company had not provided, and is not required to provide, financial support through a liquidity arrangement or otherwise, to its SPEs, including circumstances in which it could be exposed to further losses (e.g., cash shortfalls). The Company’s cumulative share of the earnings/(losses) in SPV II, SPV III and SPV IV was $0.1 million, $0.1 million, and $0.2 million for the years ended December 31, 2021, 2020, and 2019, respectively.
Copec
During March 2020, the Company entered into the JV Agreement with Compania de Petroleos de Chile Copec S.A. (“Copec”), a leading wholesaler and distributor of petroleum products, that supplies fuel, lubricants, and other retail services such as carwash and foods through its series of service stations. The Company operates more than 650 service stations in Chile and more than 2,500 through different subsidiaries companies around South America, Central America, and the United States.
The purpose of the JV Agreement is to form an entity with equity contributions from both Stem and Copec to explore and develop business opportunities within the commercial and industrial space, including utilities and grid operators, in Latin America with the focus of providing intelligent energy storage solutions that leverage advanced software analytics and controls (principally through the Athena Platform developed by Stem). Stem’s technology and expertise will be combined with the strength of Copec’s scale, distribution network, energy knowledge and other expertise areas to develop business in certain territories as defined in the JV Agreement.
The JV entity is a VIE and the Company holds a variable interest in the JV Entity. However, the Company does not have the power to direct activities that most significantly impact the economics of the JV Entity and, as such, is not the primary beneficiary. Accordingly, the Company does not consolidate the JV Entity. The Company has concluded that it has the ability to exercise significant influence over the JV Entity, and accounts for the investment using the equity method.
The following table summarizes additional information about the Company’s equity method investments, SPV II, SPV III, SPV IV and Copec:
SPV IISPV IIISPV IVCOPEC
Date formedJanuary 23, 2015June 7, 2016June 30, 2017
March 24, 2020
Initial ownership %49 %50 %50 %49 %
Stem’s interest
100% of Class A shares
100% of Class B shares
100% of Class B shares
100% of Class A shares
Initial distributions:
Class A
10% (Stem)
80% (Stem — 50%)
97.5 %To be determined
Class B90 %
20% (Stem — 100%)
2.5% (Stem)
N/A
As of December 31, 2021 and 2020, the Company’s investment in its unconsolidated SPE’s, recorded within other noncurrent assets on the consolidated balance sheets, was as follows (in thousands):
December 31,
20212020
Investment in SPV II$— $— 
Investment in SPV III421 487 
Investment in SPV IV291 257 
Copec1,212 — 
Total equity method investments$1,924 $744 
As discussed in Note 2 - Summary of Significant Accounting Policies, the Company accounts for the legal sales of the energy storage systems to the SPEs as a financing obligation. This is because the Company has significant continuing involvement in the generation of cash flows of the energy storage systems and continue to be legally responsible under the host customer contract. Accordingly, in addition to the equity method investment, the Company has the following financing obligations associated with energy storage systems legally sold to the unconsolidated SPEs (in thousands):
December 31,
20212020
Financing obligation, current portion$15,277 $14,914 
Financing obligation, noncurrent$73,204 $73,128 
Interest expense related to the financing obligations was $8.5 million, $6.9 million, and $5.8 million for the years ended December 31, 2021, 2020, and 2019, respectively.
As a result of being the accounting owner of energy storage systems sold to the SPEs and retaining the obligation to provide energy optimization services to host customers, the Company records the carrying value of energy storage system assets and obligations under the customer host contracts on its consolidated balance sheet. These balances were as follows as of December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Energy storage systems, net$92,426 $91,593 
Deferred revenue, current$4,417 $3,713 
Deferred revenue, noncurrent$10,835 $8,265 
Other liabilities$3,586 $3,178 
Because the Company is the legal party responsible for providing services to the host customer and significantly involved in generating the revenue under the host customer arrangements, the Company records the revenue associated with services, and separately records payments to the VIE as debt and interest payments. Revenues recognized by the Company associated with energy storage systems legally sold to the unconsolidated SPEs were $16.9 million, $12.8 million, and $8.8 million for the years ended December 31, 2021, 2020, and 2019, respectively. Such revenues are inclusive of incentive fees, consistent with the Company’s revenue policy. Depreciation expense recognized within cost of service revenue by the Company for the energy storage systems legally sold to the unconsolidated SPEs was $12.8 million, $11.8 million and $7.1 million for the years ended December 31, 2021, 2020, and 2019, respectively.
v3.22.0.1
NET LOSS PER SHARE
 12 Months Ended
Dec. 31, 2021
Earnings Per Share [Abstract]  
NET LOSS PER SHARE NET LOSS PER SHAREThe following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share amounts):
Year Ended
December 31,
202120202019
Numerator - Basic and Diluted:
Net loss $(101,211)$(156,124)$(59,414)
     Less: Deemed Dividend— (9,484)(5,353)
Net loss attributable to common stockholders, basic and diluted(101,211)(165,608)(64,767)
Denominator:
Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, basic and diluted105,561,139 40,064,087 42,811,383 
Net loss per share attributable to common stockholders, basic and diluted$(0.96)$(4.13)$(1.51)
The following potentially dilutive shares were not included in the calculation of diluted shares outstanding for the periods presented as the effect would have been anti-dilutive:
December 31,
202120202019
Outstanding Pre-Merger Convertible Promissory Notes— 10,495,111 5,202,697 
Outstanding 2028 Convertible Notes15,730,390 — — 
Outstanding stock options8,766,466 11,065,658 9,227,850 
Outstanding warrants23,673 10,832,616 7,672,810 
Outstanding RSUs1,799,677 — — 
Total
26,320,206 32,393,385 22,103,357 
v3.22.0.1
INCOME TAXES
 12 Months Ended
Dec. 31, 2021
Income Tax Disclosure [Abstract]  
INCOME TAXES INCOME TAXES
The components of loss before provision for income taxes for the years ended December 31, 2021, 2020, and 2019 are as follows (in thousands):
December 31,
202120202019
Domestic$(101,211)$(156,119)$(59,408)
Foreign— — — 
Loss before income taxes$(101,211)$(156,119)$(59,408)
Due to the Company’s net losses, the Company did not record a provision for federal income taxes during the years ended December 31, 2021, 2020 and 2019, respectively. The Company continues to maintain a full valuation allowance for its net U.S. federal and state deferred tax assets.
The components of the provision for income tax expense for the years ended December 31, 2021, 2020, and 2019 are as follows (in thousands):
December 31,
202120202019
Current:
Federal$— $— $— 
State— 5 6 
Total current— 5 6 
Deferred:
Federal— — — 
State— — — 
Total deferred— — — 
Total provision for income taxes$— $5 $6 
The effective tax rate of the Company’s provision (benefit) for income taxes differs from the federal statutory rate as follows:
December 31,
202120202019
Statutory rate21.00 %21.00 %21.00 %
State tax3.15 %3.19 %7.13 %
Foreign income and withholding taxes1.61 %0.41 %0.08 %
Stock-based compensation6.17 %(0.60)%(0.51)%
Change in fair value of warrants0.71 %(11.36)%0.53 %
Other(1.19)%— %(0.04)%
Non-deductible interest expense(2.53)%(1.51)%(2.63)%
Valuation allowance(28.92)%(11.13)%(25.56)%
Total— %— %— %— %
Deferred income taxes arise from temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax reporting purposes, as well as net operating losses (“NOLs”) and tax credit carryforwards.
Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2021 and 2020 are as follows (in thousands):
December 31,
20212020
Deferred tax assets:
Net operating losses$92,160 $59,960 
Tax credits741 761 
Depreciable assets604 635 
Operating lease liabilities3,558 — 
Accruals and allowances1,803 575 
Stock-based compensation1,359 83 
Deferred revenue24,734 27,962 
Interest expense1,209 — 
Other3,989 3,035 
Total gross deferred tax assets130,157 93,011 
Less: Valuation allowance(125,082)(91,315)
Net deferred tax assets5,075 1,696 
Deferred tax liabilities:
Amortization of asset retirement obligation(768)(944)
Intangibles(862)(752)
Right-of-use assets(3,445)— 
Total gross deferred tax liabilities(5,075)(1,696)
Net deferred taxes$— $— 
As of December 31, 2021 and 2020, the Company had federal NOL carryforwards of approximately $300.8 million and $199.8 million, respectively, and state NOL carryforwards of approximately $274.6 million and $200.5 million, respectively. The federal and state NOL carryforwards will both begin to expire in 2029. As of December 31, 2021 and 2020, the Company had federal research and development tax credit carryforwards of $0.7 million and $0.7 million, respectively, which begin to expire in 2029 if not utilized. As of December 31, 2021 and 2020, the Company had foreign NOL carryforwards of approximately $9.0 million and zero, respectively. As of December 31, 2021 and 2020, the Company had California research and development tax credit carryforwards of $0.7 million and $0.7 million, respectively, which do not expire. As of December 31, 2021 and 2020, the Company had California Enterprise Zone tax credits of zero and $0.1 million, respectively, which began to expire in 2021.
In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. As a result of a history of taxable losses and uncertainties as to future profitability, the Company recorded a full valuation allowance against its deferred tax assets. The valuation allowance was $125.1 million and $91.3 million as of December 31, 2021 and 2020, respectively.
Utilization of the NOL carryforwards and tax credit forwards may be subject to a substantial annual limitation due to ownership change limitations that may have occurred or that could occur in the future, as required by the Internal Revenue Code Section 382, as well as similar state provisions. In general, an “ownership change,” as defined by the code, results from a transaction or series of transactions over a three- year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders or public groups. Any limitation may result in expiration of all or a portion of the NOL or tax credit carryforwards before utilization. The Company has not performed a detailed analysis to determine whether an ownership change under Section 382 of the Code has previously occurred. As a result, the Company’s ability to utilize existing carryforwards could be restricted.
The Company had gross unrecognized tax benefits of $0.7 million and $0.8 million as of December 31, 2021 and 2020, respectively. There were no material additions, reductions or settlements of unrecognized tax benefits for years ended December 31, 2021 and 2020. The Company expects resolution of unrecognized tax benefits, if created, would occur while the full valuation allowance of deferred tax assets is maintained. The Company does not expect to have any unrecognized tax benefits that, if recognized, would affect the effective tax rate. As of December 31, 2021, the Company does not have a liability for potential penalties or interest. The Company does not expect its unrecognized tax benefits to change significantly over the next 12 months.
In the normal course of business, the Company is subject to examination by taxing authorities throughout the United States of America. The Company is not currently under audit by the Internal Revenue Service or similar state or local authorities in relation to its income taxes. The tax return years 2016 through 2020 remain open to examination by the major domestic taxing jurisdictions to which the Company is subject. Net operating losses generated on a tax return basis by the Company for calendar years 2009 through 2021 remain open to examination by the major domestic taxing jurisdictions.
v3.22.0.1
COMMITMENTS AND CONTINGENCIES
 12 Months Ended
Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]  
COMMITMENTS AND CONTINGENCIES COMMITMENTS AND CONTINGENCIESContingenciesThe Company is party to various legal proceedings from time to time arising in the ordinary course of its business. A liability is accrued when a loss is both probable and can be reasonably estimated. Management believes that the probability of a material loss with respect to any currently pending legal proceeding is remote. However, litigation is inherently uncertain and it is not possible to definitively predict the ultimate disposition of any of these proceedings. The Company does not believe that there are any pending legal proceedings or other loss contingencies that will, either individually or in the aggregate, have a material adverse effect on the Company’s consolidated financial statements
v3.22.0.1
EMPLOYER RETIREMENT PLAN
 12 Months Ended
Dec. 31, 2021
Retirement Benefits [Abstract]  
EMPLOYER RETIREMENT PLAN EMPLOYER RETIREMENT PLANThe Company sponsors a 401(k) profit sharing plan covering all eligible employees. Participants may elect to defer a percentage of their compensation ranging from 1% to 75%, up to the maximum allowable by law by making contributions to the plan. The Company may match, at its discretion, the employee contributions according to the terms of the plan. During the years ended December 31, 2021, 2020, and 2019, the Company did not match any of its employees’ contributions.
v3.22.0.1
SUBSEQUENT EVENTS
 12 Months Ended
Dec. 31, 2021
Subsequent Events [Abstract]  
SUBSEQUENT EVENTS SUBSEQUENT EVENTS
On February 1, 2022, the Company completed the acquisition of 100% of the outstanding shares of AlsoEnergy for an aggregate purchase price of $695.0 million, consisting of approximately 75% in cash and approximately 25% in shares of the Company’s common stock. The acquisition was structured on a cash-free, debt free basis and subject to other customary adjustments as set forth in the purchase agreement.
The transaction combines the Company’s storage optimization capabilities with AlsoEnergy’s solar asset performance monitoring and control software. The Company will complete the initial accounting for the acquisition during the first quarter of 2022.
v3.22.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)
 12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]  
Basis of Presentation
Basis of Presentation
The Company's consolidated financial statements have been prepared in accordance with GAAP.
Immaterial Out-of-Period Corrections Immaterial Out-of-Period Corrections
During the year ended December 31, 2021, the Company recorded certain out-of-period corrections related to prior interim and annual periods pertaining to the amortization of contract origination costs and valuation of energy storage systems that were decommissioned. The impact of out-of-period corrections to the year ended December 31, 2021 was an increase of $2.8 million to net loss, and increase to cost of service revenue of $1.7 million, and an increase to sales and marketing expenses of $1.1 million. The following table presents the amount of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, and the amounts and periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatementYear Ended December 31,
 20202019
Periods prior to 2019
Energy storage systems, net$(1.7)$(1.5)$(0.9)
Contract origination costs, net$(1.1)$(0.3)$(0.1)
Cost of service revenue$0.2 $0.6 $0.9 
Sales and marketing$0.8 $0.2 $0.1 
The Company corrected the out of period errors in the quarter ended December 31, 2021. The impact of the out-of-period correction for the quarter ended December 31, 2021 included corrections for the prior quarterly periods presented below. The impact to the quarter ended December 31, 2021, was an increase of $4.2 million to net loss, increase to cost of service revenue of $1.8 million and increase to sales and marketing expenses of $2.4 million. The following table presents the amounts of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, as well as the quarterly periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatement
 
Quarter ended September 30, 2021
Quarter ended
June 30, 2021
Quarter ended March 31, 2021
Energy storage systems, net$(1.8)$(1.7)$(1.7)
Contract origination costs, net$(2.4)$(1.6)$(1.4)
Cost of service revenue$0.1 $— $— 
Sales and marketing$0.8 $0.2 $0.3 
The errors and out of period corrections had no impact to the Company’s net cash used in operating activities for any of the periods presented. The Company performed a quantitative and qualitative evaluation of these out-of-period adjustments and has concluded that the amounts are not material in relation to the year ended December 31, 2021, or any prior interim or annual periods.
Reclassifications
Reclassifications
Certain prior year amounts have been reclassified for consistency with the current year presentation. Such reclassifications have no impact on previously reported net loss, stockholders' equity (deficit), or cash flows.
Principles of Consolidation
Principles of Consolidation
The consolidated financial statements include the accounts of the Company, its wholly-owned subsidiaries, and consolidated variable interest entities (“VIEs”). All intercompany balances and transactions have been eliminated in consolidation.
Variable Interest Entities
Variable Interest Entities
The Company forms special purpose entities (“SPEs”), some of which are VIEs, with its investors in the ordinary course of business to facilitate the funding and monetization of its energy storage systems. A legal entity is considered a VIE if it has either a total equity investment that is insufficient to finance its operations without additional subordinated financial support or whose equity holders lack the characteristics of a controlling financial interest. The Company’s variable interests arise from contractual, ownership, or other monetary interests in the entity. The typical condition for a controlling financial interest ownership is holding a majority of the voting interests of an entity; however, a controlling financial interest may also exist in entities, such as VIEs, through arrangements that do not involve controlling voting interests.
The Company consolidates a VIE if it is deemed to be the primary beneficiary. The Company determines it is the primary beneficiary if it has the power to direct the activities that most significantly impact the VIEs’ economic performance and has the obligation to absorb losses or has the right to receive benefits of the VIE that could potentially be significant to the VIE. The Company evaluates its relationships with its VIEs on an ongoing basis to determine whether it is the primary beneficiary.
Equity Method Investments Equity Method InvestmentsThe Company has ownership interests in SPEs which it does not control. Where the Company holds an interest in these SPEs of greater than 20% and has the ability to exercise significant influence, the Company uses the equity method to account for its investments in these SPEs. Under the equity method of accounting, investments are stated at initial cost and are adjusted for subsequent additional investments and the Company’s proportionate share of earnings or losses and distributions. Such proportionate share of earnings or losses is included within other expenses, net in the consolidated statements of operations. The Company considers whether its equity method investments are impaired when events or circumstances suggest that the carrying amount may not be recoverable. An impairment charge is recognized in the consolidated statements of operations for a decline in value that is determined to be other-than-temporary. In determining if and when a decline in the fair value of these investments below their carrying value is other-than-temporary, the Company evaluates the market condition, trends of earnings and cash flows and other key measures of performance and recognizes such loss which is deemed to be other-than-temporary.
Use of Estimates
Use of Estimates
The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. The Company bases its estimates on historical experience and on various other assumptions believed to be reasonable. Actual results could differ from those estimates and such differences could be material to the financial position and results of operations.
Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, depreciable life of energy systems; the amortization of financing obligations; deferred commissions and contract fulfillment costs; the valuation of energy storage systems, internally developed software, and asset retirement obligations; and the fair value of financial instruments, equity-based instruments, debt, warrant liabilities and embedded derivatives.
Segment Information Segment InformationOperating segments are defined as components of an entity for which discrete financial information is available that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s Chief Executive Officer is the CODM. The CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. As such, management has determined that the Company operates as one operating segment that is focused exclusively on innovative technology services that transform the way energy is distributed and consumed.
Cash and Cash Equivalents
Cash and Cash Equivalents
The Company considers all highly liquid investments with an original maturity date of three months or less at the date of purchase to be cash equivalents. Cash and cash equivalents are maintained at financial institutions. The Company maintains all cash in a highly liquid form to meet current obligations.
Short-Term Investments
Short-Term Investments
Investments with a maturity date greater than three months that the Company intends to convert to cash or cash equivalents within a year or less are classified as short-term investments in the Company’s consolidated balance sheets. Additionally, in accordance with ASC 320, Investments - Debt Securities, the Company has classified all short-term investments as available-for-sale securities and changes in fair market value are reported in other comprehensive income (loss).
The Company utilizes its short-term investments as an alternative form of cash and, if the cash needs arise, could liquidate the investments at any point in time regardless of the contractual maturity of the investments. All of the Company’s investments are tradable on an active market and could be sold at fair value at any point in time.
Accounts Receivable, Net Accounts Receivable, NetAccounts receivable are recorded at the invoiced amount, net of allowance for doubtful accounts. Accounts receivable also include unbilled accounts receivable, which is composed of the monthly energy optimization services provided and recognized but not yet invoiced as of the end of the reporting period. The allowance for doubtful accounts is based on the Company’s best estimate and is determined based upon a variety of factors, including analyses of specific customer receivables, aging, and overall assessments of collectability. Accounts receivable balances are charged against the allowance when the Company believes it is probable that the receivable will not be recovered.
Concentrations of Credit Risk and Other Uncertainties
Concentrations of Credit Risk and Other Uncertainties
Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and accounts receivable. The Company’s cash balances are primarily invested in money market funds or on deposit at high credit quality financial institutions in the U.S. The Company’s cash and cash equivalents are held at financial institutions where account balances may at times exceed federally insured limits. Management believes the Company is not exposed to significant credit risk due to the financial strength of the depository institution in which the cash is held. The Company has no financial instruments with off-balance sheet risk of loss.
At times, the Company may be subject to a concentration of credit risk in relation to certain customers due to the purchase of large energy storage systems made by such customers. The Company routinely assesses the creditworthiness of its customers. The Company has not experienced any material losses related to receivables from individual customers, or groups of customers during the years ended December 31, 2021, 2020 and 2019. The Company does not require collateral. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable.
Significant Customers Significant CustomersA significant customer represents 10% or more of the Company’s total revenue or accounts receivable, net balance at each reporting date.
Inventory
Inventory
Inventory consists of batteries and related components either in-process at the Company’s OEM suppliers or as a finished product at the Company’s warehouse, which are sold and delivered directly to customers under the Company’s partnership arrangements as individual assets or assembled systems. Inventory is stated at lower of cost or net realizable value with cost being determined by the specific identification method. The Company periodically reviews its inventory for potentially slow-moving or obsolete items and writes down specific items in inventory to net realizable value based on its assessment of market conditions.
Energy Storage Systems, Net
Energy Storage Systems, Net
The Company sells energy optimization services to host customers through the use of energy storage systems installed at customer locations. The Company determined that it does not transfer control of these energy storage systems to the customer, which are operated and controlled via the Company’s proprietary cloud-based software (“SaaS”) platform; therefore, these
energy storage systems do not qualify as a leased asset. The energy storage systems are stated at cost, less accumulated depreciation and impairment (as applicable).
Energy storage systems, net is comprised of equipment costs, which include components such as batteries, inverters, and other electrical equipment, and associated design, installation, and interconnection costs required to begin providing the energy optimization services to customers.
Depreciation of the energy storage systems is a component of cost of revenues within the consolidated statements of operations and is calculated using the straight-line method over the estimated useful lives of the energy storage systems, or 10 years, once the respective energy storage systems have been installed and interconnected to the power grid, the Company has received permission to operate, and the Company has begun to provide energy optimization services to the customer (i.e., energy storage system is live). Repairs and maintenance costs are expensed as incurred. Impairment charges related to energy storage system that were determined to no longer be recoverable totaled $4.3 million, $1.4 million and $0.3 million for the years ended December 31, 2021, 2020, and 2019, respectively.
Contract Origination Costs, Net, Revenue Recognition, Host Customer and Partnership Arrangements
Contract Origination Costs, Net
Contract origination costs, net is stated at gross contract origination costs less accumulated amortization. Contract origination costs consists of sales commissions earned by the Company’s sales team, as well as related payroll taxes and other relevant fringe benefits that are direct, incremental, and recoverable costs of obtaining a contract with a customer. As a result, these amounts have been capitalized on the consolidated balance sheets. The Company deferred incremental costs of obtaining a contract of $3.0 million and $2.6 million during the years ended December 31, 2021 and 2020, respectively.
Contract origination costs are amortized over the expected period of benefit. The period of benefit is estimated by considering factors such as the timing of fulfillment of performance obligations, historical customer attrition rates, the useful life of the Company’s technology, and the impact of competition in its industry. Amortization of contract costs were $3.9 million, $0.8 million and $0.5 million for the years ended December 31, 2021, 2020, and 2019, respectively, and are included in sales and marketing expense in the accompanying consolidated statements of operations.
Revenue Recognition
Revenues are recognized when control of the promised goods or services are transferred to the Company’s customers in an amount that reflects the consideration that is expected to be received in exchange for those goods or services. The Company generates all of its revenues from contracts with its customers. The Company recognizes revenue through two types of arrangements with customers, host customer arrangements and partnership arrangements as described below.

Host Customer Arrangements
Host customer contracts are generally entered into with commercial entities that have traditionally relied on power supplied directly from the grid. Host customer arrangements consist of a promise to provide energy optimization services through the Company’s proprietary SaaS platform coupled with a dedicated energy storage system owned and controlled by the Company throughout the term of the contract. The host customer does not obtain legal title to, or ownership of the dedicated energy storage system at any point in time. The host customer is the end consumer of the energy that directly benefits from the energy optimization services provided by the Company. The term for the Company’s contracts with host customers generally ranges from 5 to 10 years, which may include certain renewal options to extend the initial contract term or certain termination options to reduce the initial contract term.
Although the Company installs an energy storage system at the host customer site in order to provide the energy optimization services, the Company directs how and for what purpose the asset is used through the operation of its SaaS platform and, as such, retains control of the energy storage system; therefore, the contract does not contain a lease. The Company determines the various energy optimization services provided throughout the term of the contract, which may include services such as remote monitoring, performance reporting, preventative maintenance and other ancillary services necessary for the safe and reliable operation of the energy storage system, are part of a combined output of energy optimization services and the Company provides a single distinct combined performance obligation representing a series of distinct days of services.
The Company determines the transaction price at the outset of the arrangement, primarily based on the contractual payment terms dictated by the contract with the customer. Fees charged to customers for energy optimization services generally consist of recurring fixed monthly payments throughout the term of the contract. In certain arrangements, the transaction price may include incentive payments that are earned by the host customer from utility companies in relation to the services provided by the Company. Under such arrangements, the rights to the incentive payments are assigned by the host customer to the Company. These incentives may be in the form of fixed upfront payments, variable monthly payments, or annual performance-based payments over the first five years of the customer contract term. Incentive payments may be contingent on approval from utility companies or actual future performance of the energy storage system.
Substantially all of the Company’s arrangements provide customers the unilateral ability to terminate for convenience prior to the conclusion of the stated contractual term or the contractual term is shorter than the estimated benefit period, which the Company has determined to be 10 years based on the estimated useful life of the underlying energy storage systems and the period over which the customer can benefit from the energy optimization services utilizing such energy storage systems. In these instances, the Company determined that upfront incentive payments received from its customers represent a material right that is, in effect, an advance payment for future energy optimization services to be recognized throughout the estimated benefit period. In contracts where the customer does not have the unilateral ability to terminate for convenience without a penalty during the estimated benefit period, the Company determined the upfront incentive payments do not represent a material right for services provided beyond the initial contractual period and are therefore a component of the initial transaction price. The Company revisits its estimate of the benefit period each reporting period. The Company’s contracts with host customers do not contain a significant financing component.
The Company transfers control of its energy optimization services to its customers continuously throughout the term of the contract (a stand-ready obligation) and revenue is recognized ratably as control of these services is transferred to its customers, in an amount that reflects the consideration the Company expects to be contractually entitled to in exchange for its services. Monthly incentive payments based on the performance of the energy storage system are allocated to the distinct month in which they are earned because the terms of the payments relate specifically to the outcome from transferring the distinct time increment (month) of service and because such amounts reflect the fees to which the Company expects to be entitled for providing energy optimization services each period, consistent with the allocation objective. Annual variable performance- based payments are estimated at the inception in the transaction price using the expected value method, which takes into consideration historical experience, current contractual requirements, specific known market events and forecasted energy storage system performance patterns, and the Company recognizes such payments ratably using a time-based measure of progress of days elapsed over the term of the contract to the extent that it is probable that a significant reversal of the cumulative revenue recognized will not occur in a future period. At the end of each reporting period, the Company reassesses its estimate of the transaction price. The Company does not begin recognition of revenue until the energy storage system is live (i.e., provision of energy optimization services has commenced) or, as it relates to incentive payments, when approval has been received from the utility company, if later.
Partnership Arrangements
Partnership arrangements consist of promises to transfer inventory in the form of an energy storage system to a “solar plus storage” project developer and separately provide energy optimization services as described previously to the ultimate owner of the project after the developer completes the installation of the project. Under partnership arrangements, the Company’s customer is the solar plus storage project developer. The customer obtains legal title to along with ownership and control of the inventory upon delivery and the customer is responsible for the installation of the project. Once installation of the project is complete, the owner of the solar plus storage project provides energy to the end consumer through a separate contractual arrangement directly with the end consumer. The term for the Company’s contracts with customers under partnership arrangements generally ranges from 10 to 20 years.
The Company determined the promise to deliver the inventory as a component of the solar plus storage project for which the customer is responsible to develop is a separate and distinct performance obligation from the promise to provide energy optimization services.
The Company determines the transaction price at the outset of the arrangement, primarily based on the contractual payment terms dictated by the contract with the customer. Fees charged for the sale of inventory generally consist of fixed fees payable upon or shortly after successful delivery to the customer. Fees charged to customers for energy optimization services consist of recurring fixed monthly payments throughout the term of the contract. The Company is responsible for designing, procuring, delivering and ensuring the proper components are provided in accordance with the requirements of the contract. Although the inventory is purchased by the Company from a third-party manufacturer, the Company determined it obtains control of the inventory prior to delivery to the customer and is the principal in the arrangement. The Company is fully responsible for responding to and correcting any customer issues related to the delivery of the inventory. The Company holds title and assumes all risks of loss associated with the inventory until the customer accepts the inventory. The Company is primarily responsible for fulfilling the delivery of the inventory to the customer, assumes substantial inventory risks and has discretion in the pricing charged to the customer. The Company has not entered into any partnership arrangements where it is not the principal in the transaction.
The Company allocates revenue between the hardware and energy storage services performance obligations based on the standalone selling price of each performance obligation. The standalone selling price for the hardware is established based on observable pricing. The standalone selling price for the energy optimization services is established using a residual value approach due to the significant variability in the services provided to each individual customer based on the specific requirements of each individual project and the lack of observable standalone sales of such services. The Company’s partnership arrangements do not contain a significant financing component.
The Company transfers control of the inventory upon delivery and simultaneous transfer of title to the customer. The Company transfers control of its energy optimization services to its customers continuously throughout the term of the contract (a stand-ready obligation), which does not commence until the customer successfully completes the installation of the project. As a result, the time frame between when the Company transfers control of the inventory to the customer upon delivery is generally several months, and can be in excess of one year, before the Company is required to perform any subsequent energy optimization services. Revenue is recognized ratably as control of these services is transferred to its customers based on a time-based output measure of progress of days elapsed over the term of the contract, in an amount that reflects the consideration the Company expects to be entitled to in exchange for its services.
In some partnership arrangements, the Company charges shipping fees for the inventory. The Company accounts for shipping as a fulfillment activity, since control transfers to the customer after the shipping is complete and includes such amounts within cost of revenue.
Business Combinations
Business Combinations
The Company accounts for business acquisitions under ASC 805, Business Combinations. The total purchase consideration for an acquisition is measured as the fair value of the assets given, equity instruments issued and liabilities assumed at the acquisition date. Costs that are directly attributable to the acquisition are expensed as incurred. Identifiable assets (including intangible assets), liabilities assumed (including contingent liabilities) and noncontrolling interests in an acquisition are measured initially at their fair values at the acquisition date. The Company recognizes goodwill if the fair value of the total purchase consideration and any noncontrolling interests is in excess of the net fair value of the identifiable assets acquired and the liabilities assumed. The Company recognizes a bargain purchase gain within other income (expense), net, on the consolidated statement of operations if the net fair value of the identifiable assets acquired and the liabilities assumed is in excess of the fair value of the total purchase consideration and any noncontrolling interests. The Company includes the results of operations of the acquired business in the consolidated financial statements beginning on the acquisition date.
Internal-use software Internal-use softwareThe Company capitalizes costs incurred in the development of internal-use software during the application development stage. Costs related to preliminary project activities and post-implementation activities are expensed as incurred. Capitalized internal-use software is amortized on a straight-line basis over the estimated useful life of the software once it is ready for its intended use.
Finite-lived Intangible Assets
Finite-lived Intangible Assets
Finite-lived intangible assets consist of developed technology acquired in a business combination. Finite-lived intangible assets acquired in business combinations are initially recorded at fair value and subsequently presented net of accumulated
amortization. These intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company amortizes its developed technology over five years.
Impairment of Long-Lived Assets
Impairment of Long-Lived Assets
The Company reviews its long-lived assets, which primarily consist of energy storage systems, right-of- use assets, and finite-lived intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable or that the useful life is shorter than originally estimated. Recoverability of assets is measured by comparing the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset over its remaining useful life.
If such assets are impaired, the impairment recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. If the useful life is shorter than originally estimated, the Company depreciates or amortizes the remaining carrying value over the revised shorter useful life. Assets to be disposed of by sale are reflected at the lower of their carrying amount or fair value less cost to sell.
Leases
Leases
The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The classification of the Company’s leases as operating or finance leases along with the initial measurement and recognition of the associated ROU assets and lease liabilities is performed at the lease commencement date. The measurement of ROU assets and lease liabilities is based on the present value of future lease payments over the lease term. The ROU asset also includes the effect of any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable.
As the implicit rate in the Company’s leases is generally unknown, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The Company considers its credit risk, term of the lease, total lease payments and adjusts for the impacts of collateral, as necessary, when calculating its incremental borrowing rates. The lease terms may include options to extend or terminate the lease when it is reasonably certain the Company will exercise any such options. Rent expense for the Company’s operating leases is recognized on a straight-line basis over the lease term. Variable lease payments are recorded as an expense in the period incurred.
The Company has elected to not separate lease and non-lease components for any leases within its existing classes of assets and, as a result, accounts for any lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases within its existing classes of assets with a term of 12 months or less.
Convertible Preferred Stock Warrant Liabilities
Convertible Preferred Stock Warrant Liabilities
The Company evaluates whether its warrants for shares of convertible redeemable preferred stock are freestanding financial instruments that obligate the Company to redeem the underlying preferred stock at some point in the future and determined that each of its outstanding warrants for preferred stock are liability classified. The warrants are subject to re-measurement at each balance sheet date, and any change in fair value is recognized in the change in fair value of warrants and embedded derivatives in the consolidated statements of operations.
As discussed in Note 13 - Warrants, upon effectiveness of the Merger, substantially all of the outstanding convertible preferred stock warrants were converted into shares of common stock of Stem. As such, the associated warrant liability was reclassified to additional paid-in-capital upon the Merger and was no longer an outstanding Level 3 financial instrument as of December 31, 2021.
Common Stock Warrants
Common Stock Warrants
The Company evaluates common stock warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity. The Company assesses whether common stock warrants are freestanding financial instruments and whether they meet the criteria to be classified in stockholders’ equity, or classified as a liability. Where common stock warrants do not meet the conditions to be classified in equity, the Company assesses whether they meet the definition of a liability under ASC 815.
Common stock warrants that meet the definition of a liability are recognized on the balance sheet at fair value. Subsequent changes in their respective fair values are recognized in the consolidated statement of operations at each reporting date.As indicated in Note 13 - Warrants, as part of STPK’s initial public offering, the Company issued Public Warrants and Private Warrants, which upon issuance met the criteria for liability classification under ASC 815.
Asset Retirement Obligations
Asset Retirement Obligations
The Company recognizes a liability for the fair value of asset retirement obligations (“ARO”) associated with its energy storage systems in the period in which there is a legal obligation associated with the retirement of such assets and the amount can be reasonably estimated. The associated asset retirement costs are capitalized as part of the carrying amount of the energy storage systems and depreciated over the asset’s remaining useful life. This liability includes costs related to the removal of its energy storage systems at the conclusion of each respective customer contract. Subsequent to initial measurement, the asset retirement liability is accreted each period and such accretion is recognized as an expense in the consolidated statements of operations. If there are changes in the estimated amount or timing of cash flows, a revision is recorded to both the asset retirement obligation and the asset retirement capitalized cost.
Financing Obligations
Financing Obligations
The Company has formed various SPEs to finance the development and construction of its energy storage systems. These SPEs, which are structured as limited liability companies, obtain financing in the form of large upfront payments from outside investors and purchase energy storage systems from the Company under master purchase agreements. The Company accounts for the large upfront payments received from the fund investor as a borrowing by recording the proceeds received as a financing obligation, which will be repaid through host customer payments and incentives received from the utilities that will be received by the investor.
The financing obligation is non-recourse once the associated energy storage systems have been placed in-service and the associated customer arrangements have been assigned to the SPE. However, the Company is responsible for any warranties, performance guarantees, accounting, performance reporting, and all other costs associated with the operation of the energy storage systems. Despite such energy storage systems being legally sold to the SPEs, the Company recognizes host customer payments and incentives as revenue during the period as discussed in Note 3 - Revenue. The amounts received by the fund investor from customer payments and incentives are recognized as interest using the effective interest method, and the balance is applied to reduce the financing obligation. The effective interest rate is the interest rate that equates the present value of the cash amounts to be received by a fund investor in relation to the underlying Projects with the present value of the cash amounts paid by the investor to the Company, adjusted for any payments made by the Company.
Fair Value of Financial Instruments
Fair Value of Financial Instruments
Assets and liabilities recorded at fair value in the consolidated financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. The fair value of the Company’s financial assets and liabilities reflects management’s estimate of amounts that the Company would have received in connection with the sale of the assets or paid in connection with the transfer of the liabilities in an orderly transaction between market participants at the measurement date. In connection with measuring the fair value of its assets and liabilities, the Company seeks to maximize the use of observable inputs (market data obtained from independent sources) and to minimize the use of unobservable inputs (internal assumptions about how market participants would price assets and liabilities).

Hierarchical levels which are directly related to the amount of subjectivity associated with the inputs to the valuation of these assets or liabilities are as follows:
Level 1 — Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access as of the measurement date.
Level 2 — Inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data.
Level 3 — Unobservable inputs for the asset or liability only used when there is little, if any, market activity for the asset or liability at the measurement date.
This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. Assets and liabilities measured at fair value are classified in their entirety
based on the lowest level of input that is significant to their fair value measurement. The Company’s assessment of the significance of a specific input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.Financial assets and liabilities held by the Company measured at fair value on a recurring basis as of December 31, 2021 and 2020, include cash and cash equivalents, short-term investments, warrant liabilities and embedded derivatives which are bifurcated from the host financial instrument.
Cost of Revenue
Cost of Revenue
Cost of Hardware Revenue
Cost of revenue related to the sale of hardware includes the cost of the hardware sold to project developers, which generally includes the cost to purchase the hardware from a manufacturer, shipping, and other costs required to fulfill the Company’s obligation to deliver the hardware to the customer location. Cost of revenue may also include any impairment of hardware held in inventory for sale to a customer. Cost of revenue related to the sale of hardware is recognized when the delivery of the hardware is completed.
Cost of Service Revenue
Cost of revenue related to energy optimization services includes depreciation of the cost of energy storage systems associated with long-term host customer contracts, which includes capitalized fulfillment costs, such as installation services, permitting and other related costs. Cost of revenue may also include any impairment of energy storage systems along with energy storage system maintenance costs associated with the ongoing services provided to customers and other amounts not qualifying for capitalization pursuant to the Company’s internal use software capitalization policy. Cost of revenue is recognized as the energy optimization and other supporting services are provided to the Company’s customers throughout the term of the contract.
Sales and Marketing Sales and MarketingSales and marketing expense consists primarily of payroll and other related personnel costs, including stock-based compensation, employee benefits, and travel for the Company’s sales & marketing department. These costs are recognized in the period incurred.
Research and Development
Research and Development
Research and development expense consists primarily of payroll and other related personnel costs for engineers and third parties engaged in the design and development of products, third-party software, and technologies, including salaries, bonus and stock-based compensation expense, project material costs, services, and depreciation. The Company expenses research and development costs as they are incurred.
General and Administrative
General and Administrative
General and administrative expense consists of payroll and other related personnel costs, including salaries, bonuses and stock-based compensation for executive management, legal, finance, and others. In addition, general and administrative expense includes fees for professional services and occupancy costs.
Stock Based Compensation Stock-Based CompensationThe Company recognizes stock-based compensation expense related to employees over the requisite service period based on the grant-date fair value of the awards. The fair value of options granted is estimated using the Black-Scholes option valuation model. The Company recognizes the grant-date fair value of an award as compensation expense on a straight-line basis over the requisite service period, which typically corresponds to the vesting period for the award. The Company elects to account for forfeitures as they occur and, upon forfeiture of an award prior to vesting, the Company reverses any previously recognized compensation expense related to that award.
Income Taxes
Income Taxes
The Company uses the asset and liability method of accounting for income taxes based on ASC 740, Accounting for Income Taxes. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between financial statement carrying amounts and the tax basis of existing assets and liabilities. The Company records a valuation allowance to reduce tax assets to an amount for which realization is more likely than not. There are certain charges that are not deductible for tax purposes.
In evaluating the ability to recover its deferred income tax assets, the Company considers all available positive and negative evidence, including its operating results, ongoing tax planning, and forecasts of future taxable income on a jurisdiction-by-jurisdiction basis. In the event the Company determines that it would be able to realize its deferred income tax assets in the future in excess of their net recorded amount, it would make an adjustment to the valuation allowance that would reduce the provision for income taxes. Conversely, in the event that all or part of the net deferred tax assets are determined not to be realizable in the future, an adjustment to the valuation allowance would be charged to earnings in the period such determination is made.
The Company recognizes the tax benefit from uncertain tax positions in accordance with GAAP, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of uncertain tax positions taken or expected to be taken in the Company’s tax return. No liability related to uncertain tax positions has been recognized in the financial statements.
The Company includes interest and penalties for uncertain tax positions in the financial statements as a component of income tax expense.
Foreign Currency Translation
Foreign Currency Translation
The Company’s foreign subsidiaries financial position and results of operations are measured using the local currency as the functional currency. The functional currency is the currency of the primary economic environment in which an entity’s operations are conducted. Assets and liabilities of foreign subsidiaries are translated at exchange rates in effect as of the balance sheet date. Revenues and expenses are translated at average exchange rates in effect during the year. Translation adjustments are recorded within accumulated other comprehensive loss, a separate component of stockholders’ equity (deficit).
Net Loss Per Share Attributable to Common Stockholders
Net Loss Per Share Attributable to Common Stockholders
Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted- average number of common shares and common share equivalents of potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible notes, warrants, restricted stock units (“RSUs”), and common stock options are considered to be potentially dilutive securities. As the Company was in a net loss position for the years ended December 31, 2021, 2020, and 2019, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders because the effects of potentially dilutive securities are antidilutive.
Recently Adopted Accounting Standards And Recently Issued Accounting Standards
Recently Adopted Accounting Standards
In August 2018, the FASB issued ASU 2018-15, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). The intent of this pronouncement is to align the requirements for capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software as defined in ASC 350-40. Under ASU 2018-15, the capitalized implementation costs related to a cloud computing arrangement will be amortized over the term of the arrangement and all capitalized implementation amounts will be required to be presented in the same line items of the financial statements as the
related hosting fees. ASU 2018-15 is effective for public and private companies’ fiscal years beginning after December 15, 2019, and December 15, 2020, respectively, and interim periods within those fiscal years, with early adoption permitted. The Company adopted ASU 2018-15 as of January 1, 2021. The adoption did not have a material effect on the Company’s consolidated financial statements.
In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”). ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 was effective for public entities for interim and annual periods beginning after December 15, 2020, with early adoption permitted. ASU 2019-12 will be effective for private entities for annual periods beginning after December 15, 2021, and interim periods beginning after December 15, 2020, with early adoption permitted. The Company adopted ASU 2019-12 effective May 1, 2021. The adoption of this standard did not have a material impact on the Company's consolidated financial statements.
Recently Issued Accounting Standards
The Company will adopt ASU 2020-06 Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, effective January 1, 2022 using the modified retrospective approach. As a result of the adoption of ASU 2020-06, the 2028 Convertible Notes will no longer bifurcated into separate liability and equity components in the March 31, 2022 condensed consolidated balance sheet. Rather, the $460.0 million principal amount of the Company’s 2028 Convertible Notes will be classified only as a liability prospectively in the balance sheet. Upon adoption of ASU 2020-06, an adjustment will be recorded to the convertible notes liability component, equity component (additional paid-in-capital) and retained earnings. The cumulative effect of the change will be recognized as an adjustment to the opening balance of retained earnings at the date of adoption. The comparative information will not restated and will continue to be presented according to accounting standards in effect for those periods. The adjustment will be calculated based on the carrying amount of the 2028 Convertible Notes as if it had always been treated only as a liability. Interest expense recognized in future periods will be reduced as a result of accounting for the convertible debt instrument as a single liability measured at its amortized cost.

In June 2016, the FASB issued ASU 2016-13, Financial instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and subsequent related ASUs, which amends the guidance on the impairment of financial instruments by requiring measurement and recognition of expected credit losses for financial assets held. This ASU is effective for public and private companies’ fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2019, and December 15, 2022, respectively. As the Company is no longer an emerging growth company as of January 1, 2022, the Company plans to adopt ASU 2016-13 effective on such date, utilizing the modified retrospective transition method. The Company believes that adoption of ASU 2016-13 will not have a material impact on the Company’s consolidated financial statements.
In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. Under ASU 2021-08, an acquirer must recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with Topic 606. The guidance is effective for interim and annual periods beginning after December 15, 2022, with early adoption permitted. As indicated in Note 21 - Subsequent Events, the Company completed the acquisition of AlsoEnergy on February 1, 2022. Therefore, the Company plans to adopt ASU 2021-08 on a prospective basis effective January 1, 2022 and is currently assessing the effect, if any, the guidance will have on the Company's consolidated financial statements.
v3.22.0.1
BUSINESS (Tables)
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule Of Reverse Recapitalization On April 28, 2021, shareholders of STPK approved the Merger, under which Stem received approximately $550.3 million, net of fees and expenses as follows (in thousands):
Recapitalization
Cash — STPK trust and working capital cash$383,383 
Cash — PIPE (as described below)225,000 
Less: transaction costs and advisory fees paid(58,061)
Merger and PIPE financing$550,322 
v3.22.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)
 12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]  
Schedule of Error Corrections and Prior Period Adjustments The following table presents the amount of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, and the amounts and periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatementYear Ended December 31,
 20202019
Periods prior to 2019
Energy storage systems, net$(1.7)$(1.5)$(0.9)
Contract origination costs, net$(1.1)$(0.3)$(0.1)
Cost of service revenue$0.2 $0.6 $0.9 
Sales and marketing$0.8 $0.2 $0.1 
The Company corrected the out of period errors in the quarter ended December 31, 2021. The impact of the out-of-period correction for the quarter ended December 31, 2021 included corrections for the prior quarterly periods presented below. The impact to the quarter ended December 31, 2021, was an increase of $4.2 million to net loss, increase to cost of service revenue of $1.8 million and increase to sales and marketing expenses of $2.4 million. The following table presents the amounts of the errors identified for energy storage systems, net and contract origination costs, net as of the end of each period, as well as the quarterly periods in which the errors related to cost of service revenue and sales and marketing originated (in millions):
(overstatement)/understatement
 
Quarter ended September 30, 2021
Quarter ended
June 30, 2021
Quarter ended March 31, 2021
Energy storage systems, net$(1.8)$(1.7)$(1.7)
Contract origination costs, net$(2.4)$(1.6)$(1.4)
Cost of service revenue$0.1 $— $— 
Sales and marketing$0.8 $0.2 $0.3 
Summary of Significant Customers For each significant customer, revenue as a percentage of total revenue and accounts receivable as a percentage of total accounts receivable are as follows:
Accounts ReceivableRevenue
December 31,Year Ended December 31,
20212020202120202019
Customers:
Customer A23 %*11 %**
Customer B15 %*10 %12 %*
Customer C13 %17 %10 %25 %*
Customer D*30 %***
Customer E*20 %***
*Total less than 10% for the respective period
v3.22.0.1
REVENUE (Tables)
 12 Months Ended
Dec. 31, 2021
Revenue from Contract with Customer [Abstract]  
Disaggregation of Revenue
The following table provides information on the disaggregation of revenue as recorded in the consolidated statements of operations (in thousands):
Year ended December 31,
202120202019
Partnership hardware and service revenue
$107,135 $20,713 $4,076 
Host customer service revenue
20,236 15,594 13,476 
Total revenue
$127,371 $36,307 $17,552 
Remaining Performance Obligations As of December 31, 2021, the Company had $217.8 million of remaining performance obligations, and the approximate percentages expected to be recognized as revenue in the future are as follows (in thousands, except percentages):
Total remaining
performance
obligations		Percent Expected to be Recognized as Revenue
Less than
one year		Two to
five years		Greater than
five years

Service revenue
$169,758 12 %50 %38 %
Hardware revenue
48,039 100 %— %— %
Total revenue$217,797 
Contract Balances The following table presents the changes in the deferred revenue balance (in thousands):
202120202019
Beginning balance as of Beginning balance as of January 1,$52,410 $20,728$11,859
Upfront payments received from customers89,951 40,4816,698
Upfront or annual incentive payments received6,614 8,015 8,240 
Revenue recognized related to amounts that were included in beginning balance of deferred revenue(33,585)(9,764)(4,830)
Revenue recognized related to deferred revenue generated during the period(77,947)(7,050)(1,239)
Ending balance as of Ending balance as of December 31,$37,443 $52,410 $20,728 
v3.22.0.1
SHORT-TERM INVESTMENTS (Tables)
 12 Months Ended
Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]  
Schedule of Short-Term Investments
The following tables summarize the estimated fair value of the Company’s cash equivalents and debt securities and the gross unrealized holding gains and losses as of December 31, 2021 (in thousands):


Amortized costUnrealized gainUnrealized LossEstimated Fair Value
Assets
Cash equivalents:
Money market fund$127,261 $— $— $127,261 
Total cash equivalents$127,261 $— $— $127,261 
Debt securities:
Corporate debt securities$42,174 $11 $(52)$42,133 
Commercial paper20,743 — — 20,743 
U.S. government bonds86,265 — (135)86,130 
Certificate of deposits21,501 6 — 21,507 
Other2,500 — (5)2,495 
Total debt securities$173,183 $17 $(192)$173,008 
Classified as:
Cash equivalents$127,261 
Short-term debt securities173,008 
Long-term debt securities— 
v3.22.0.1
FAIR VALUE MEASUREMENTS (Tables)
 12 Months Ended
Dec. 31, 2021
Fair Value Disclosures [Abstract]  
Schedule of Financial Instruments Measured at Fair Value
The following table provides the financial instruments measured at fair value on a recurring basis (in thousands):
December 31, 2021
Level 1Level 2Level 3Total
Assets
Cash equivalents:
Money market fund
$127,261$— $—$127,261
Debt securities
Corporate debt securities— 42,133 — 42,133
Commercial paper— 20,743 — 20,743
U.S. government bonds— 86,130 — 86,130
Certificate of deposits— 21,507 — 21,507
Other— 2,495 — 2,495 
Total financial assets$127,261 $173,008 $— $300,269 

December 31, 2020
Level 1Level 2Level 3Total
Assets
Cash equivalents:
Money market fund
$67 $— $— $67 
Liabilities
Convertible preferred stock warrant liability
$— $— $95,342 $95,342 
Key Assumptions Used for Valuation
The key assumptions used for the valuation of the preferred stock warrant liabilities upon remeasurement were as follows:
Year Ended December 31, 2021
Volatility65.0 %
Risk-free interest rate0.1 %
Expected term (in years)1.5
Dividend yield— %
Discount for lack of marketability12.3 %
Schedule of Changes in Liability for Unobservable Inputs The following table presents the changes in the liability for the Company’s warrants during the years ended December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Balance as of January 1,
$95,342 $6,094 
Changes in estimated fair value488 85,623 
Assumption of warrant liability upon Merger302,556 — 
Issuance of warrants— 3,633 
Conversion of warrants upon Merger(60,568)— 
Exchange of warrants (168,647)— 
Exercise of warrants(169,171)(8)
Balance as of December 31,
$— $95,342 
v3.22.0.1
GOODWILL AND INTANGIBLE ASSETS, NET (Tables)
 12 Months Ended
Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Goodwill
Goodwill consists of the following (in thousands):
December 31,
20212020
Goodwill$1,625 $1,625 
Effect of foreign currency translation116 114 
Total goodwill$1,741 $1,739 
Schedule of Intangible Assets
Intangible assets, net, consists of the following (in thousands):
December 31,
20212020
Developed technology$500 $500 
Internally developed software29,706 22,545 
Intangible assets30,206 23,045 
Less: Accumulated amortization(16,276)(10,993)
Add: Currency translation adjustment36 35 
Total intangible assets, net$13,966 $12,087 
v3.22.0.1
LEASES (Tables)
 12 Months Ended
Dec. 31, 2021
Leases [Abstract]  
Schedule of operating lease liabilities
As of December 31, 2021, future payments associated with the Company’s operating lease liabilities were as follows (in thousands):
Operating
Leases
2022$1,818 
20232,473 
20242,239 
20252,109 
20262,172 
Thereafter4,937 
Total lease payments15,748 
Less: imputed interest(2,325)
Total operating lease liability future lease payments$13,423 
Summary of lease information
Reported as of December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Current portion of operating lease liabilities included within other current liabilities
$1,240 $333 
Non-current portion of operating lease liabilities12,183 57 
Total$13,423 $390 
The following summarizes additional information related to operating leases:
December 31,
20212020
Weighted average remaining operating lease term (in years)6.70.8
Weighted average discount rate4.5 %11.3 %
v3.22.0.1
ASSET RETIREMENT OBLIGATION (Tables)
 12 Months Ended
Dec. 31, 2021
Asset Retirement Obligation Disclosure [Abstract]  
Summary of Asset Retirement Obligations
The information below details the asset retirement obligation for the years ended December 31, 2021 and 2020 as follows (in thousands):
December 31,
20212020
Beginning balance at January 1,$4,137 $5,759 
Asset retirement obligation— 771 
Settlement of asset retirement obligation— (1,375)
Retirement cost revaluation(231)(1,235)
Accretion expense229 217 
Ending balance at December 31,$4,135 $4,137 
v3.22.0.1
ENERGY STORAGE SYSTEMS, NET (Tables)
 12 Months Ended
Dec. 31, 2021
Property, Plant and Equipment [Abstract]  
Schedule of Energy Storage Systems, Net Energy storage systems, net, consists of the following (in thousands):
December 31, 2021December 31, 2020
Energy storage systems placed into service$143,592 $144,425 
Less: accumulated depreciation(45,250)(33,389)
Energy storage systems not yet placed into service7,772 12,667 
Total energy storage systems, net$106,114 $123,703 
v3.22.0.1
BALANCE SHEET COMPONENTS (Tables)
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Inventory
Inventory consists of the following (in thousands):
December 31,
20212020
Work in process inventory$20,582 $15,296 
Batteries2,138 5,547 
Total inventory$22,720 $20,843 
Schedule of Other Current Assets
Other current assets consist of the following (in thousands):
December 31,
20212020
Deferred costs with suppliers$13,744 $6,204 
Prepaid expenses3,137 698 
Utility program deposits353 891 
Due from related parties213 123 
Other1,194 4 
Total other current assets$18,641 $7,920 
Schedule of Other Assets, Noncurrent
Other noncurrent assets consist of the following (in thousands):
December 31,
20212020
Prepaid warranties and maintenance$15,991 $1,088 
Receivable from SPEs (Note 16)3,565 3,583 
Deferred SPAC costs— 1,256 
Self-generation incentive program deposits940 1,036 
Investment in VIEs1,924 744 
Revolver debt issuance costs— 73 
Property and equipment, net512 44 
Other1,599 458 
Total other noncurrent assets$24,531 $8,282 
Schedule of Accrued Liabilities
Accrued liabilities consist of the following (in thousands):
December 31,
20212020
Accrued payables$25,062 $9,799 
Accrued interest – notes payable344 6,149 
Other accrued liabilities587 124 
Total accrued liabilities$25,993 $16,072 
Other Current Liabilities
Other current liabilities consist of the following (in thousands):
December 31,
20212020
System advances$267 $640 
Lease liabilities – current portion1,240 333 
Due to related parties306 399 
Other— 217 
Total other current liabilities$1,813 $1,589 
v3.22.0.1
NOTES PAYABLE (Tables)
 12 Months Ended
Dec. 31, 2021
Debt Disclosure [Abstract]  
Schedule of Outstanding Debt The Company’s outstanding debt consisted of the following as of December 31, 2021 (in thousands):
December 31, 2021
Outstanding principal$1,902 
Unamortized discount(215)
Carrying value of debt$1,687 
v3.22.0.1
CONVERTIBLE PROMISSORY NOTES (Tables)
 12 Months Ended
Dec. 31, 2021
Debt Disclosure [Abstract]  
Schedule Of Convertible Debt These costs were allocated to the debt and equity components based on the allocation of the proceeds as follows (in thousands):
AmountEquity ComponentDebt Component
Initial Purchaser’s Debt Discount$12,420 $3,650 $8,770 
Debt Issuance Costs1,871 550 1,321 
Total$14,291 $4,200 $10,091 
The outstanding 2028 Convertible Notes balances as of December 31, 2021, are summarized in the following table (in thousands):
December 31, 2021
Debt Component
Outstanding principal$460,000 
Unamortized initial purchaser’s debt discount and debt issuance cost(143,458)
Net carrying amount$316,542 
The following table presents total interest expense recognized related to the 2028 Convertible Notes during the year ended December 31, 2021 (in thousands):
December 31, 2021
Cash interest expense
Contractual interest expense$249 
Non-cash interest expense
Amortization of debt discount and debt issuance cost$1,812 
Total interest expense$2,061 
v3.22.0.1
COMMON STOCK (Tables)
 12 Months Ended
Dec. 31, 2021
Equity [Abstract]  
Common Stock Reserved For Issuance The Company had reserved shares of common stock for issuance as follows:
December 31,
2021
Shares reserved for warrants23,673
Options issued and outstanding8,766,466
Shares available for future issuance under equity incentive plan20,844,788
Conversion of 2028 Convertible Notes20,842,773
Total 50,477,700
v3.22.0.1
STOCK-BASED COMPENSATION (Tables)
 12 Months Ended
Dec. 31, 2021
Share-based Payment Arrangement [Abstract]  
Summary of Activity Under the Plan
The following table summarizes the stock option activity for the period ended December 31, 2021:
Number of
Options
Outstanding		Weighted-
Average
Exercise Price
Per Share		Weighted-
Average
Remaining
Contractual
Life (years)		Aggregate
Intrinsic
Value
(in thousands)
Balances as of December 31, 202051,379,939 $0.56 7.2$46,516 
Retroactive application of recapitalization(40,314,281)2.05 —— 
Adjusted Balance as of December 31, 202011,065,658 2.61 7.246,516 
Options granted1,079,583 28.73 
Options exercised(3,235,713)1.64 
Options forfeited(129,102)15.18 
Options expired(13,960)0.53
Balances as of December 31, 20218,766,466 $6.01 7.1$123,570 
Options vested and exercisable — December 31, 20216,298,675 $2.61 6.4$103,100 
Schedule of Assumptions in Estimating Option Fair Value
The Company uses the Black-Scholes model for estimating the fair value of options granted. The weighted-average assumptions used in the Black-Scholes are as follows:
December 31,
202120202019
Expected volatility74.00 %71.41 %69.10 %
Risk-free interest rate1.06 %0.49 %2.47 %
Expected term (years)6.235.825.83
Dividend yield———
Schedule of Restricted Stock Activity The following table summarizes the RSU activity for the period ended December 31, 2021:
Number of
RSUs
Outstanding		Weighted-
Average
Grant Date Fair Value
Per Share
Balances as of December 31, 2020—$— 
RSUs granted1,801,83136.0 
RSUs vested—— 
RSUs forfeited(2,154)26.1 
Balances as of December 31, 20211,799,67736.0 
Stock-based Compensation Expense
The following table summarizes stock-based compensation expense recorded in each component of operating expenses in the Company’s consolidated statements of operations and comprehensive loss (in thousands):
Year Ended December 31,
202120202019
Sales and marketing$1,723 $396 $364 
Research and development2,367 1,211 901 
General and administrative9,456 2,935 266 
Total stock-based compensation expense$13,546 $4,542 $1,531 
v3.22.0.1
SPECIAL PURPOSE ENTITIES (Tables)
 12 Months Ended
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Variable Interest Entities The assets and liabilities of SCF 1 are comprised primarily of the following:
December 31,
20212020
Energy storage systems, net$649 $1,463 
Deferred revenue, current$283 $283 
Deferred revenue, noncurrent$753 $1,047 
Other liabilities$159 $239 
These balances were as follows as of December 31, 2021 and 2020 (in thousands):
December 31,
20212020
Energy storage systems, net$92,426 $91,593 
Deferred revenue, current$4,417 $3,713 
Deferred revenue, noncurrent$10,835 $8,265 
Other liabilities$3,586 $3,178 
Schedule of Equity Method Investments
The following table summarizes additional information about the Company’s equity method investments, SPV II, SPV III, SPV IV and Copec:
SPV IISPV IIISPV IVCOPEC
Date formedJanuary 23, 2015June 7, 2016June 30, 2017
March 24, 2020
Initial ownership %49 %50 %50 %49 %
Stem’s interest
100% of Class A shares
100% of Class B shares
100% of Class B shares
100% of Class A shares
Initial distributions:
Class A
10% (Stem)
80% (Stem — 50%)
97.5 %To be determined
Class B90 %
20% (Stem — 100%)
2.5% (Stem)
N/A
As of December 31, 2021 and 2020, the Company’s investment in its unconsolidated SPE’s, recorded within other noncurrent assets on the consolidated balance sheets, was as follows (in thousands):
December 31,
20212020
Investment in SPV II$— $— 
Investment in SPV III421 487 
Investment in SPV IV291 257 
Copec1,212 — 
Total equity method investments$1,924 $744 
Accordingly, in addition to the equity method investment, the Company has the following financing obligations associated with energy storage systems legally sold to the unconsolidated SPEs (in thousands):
December 31,
20212020
Financing obligation, current portion$15,277 $14,914 
Financing obligation, noncurrent$73,204 $73,128 
v3.22.0.1
NET LOSS PER SHARE (Tables)
 12 Months Ended
Dec. 31, 2021
Earnings Per Share [Abstract]  
Schedule of Computation of Basic and Diluted Net Loss Per Share The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share amounts):
Year Ended
December 31,
202120202019
Numerator - Basic and Diluted:
Net loss $(101,211)$(156,124)$(59,414)
     Less: Deemed Dividend— (9,484)(5,353)
Net loss attributable to common stockholders, basic and diluted(101,211)(165,608)(64,767)
Denominator:
Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, basic and diluted105,561,139 40,064,087 42,811,383 
Net loss per share attributable to common stockholders, basic and diluted$(0.96)$(4.13)$(1.51)
Schedule of Potentially Dilutive Shares
The following potentially dilutive shares were not included in the calculation of diluted shares outstanding for the periods presented as the effect would have been anti-dilutive:
December 31,
202120202019
Outstanding Pre-Merger Convertible Promissory Notes— 10,495,111 5,202,697 
Outstanding 2028 Convertible Notes15,730,390 — — 
Outstanding stock options8,766,466 11,065,658 9,227,850 
Outstanding warrants23,673 10,832,616 7,672,810 
Outstanding RSUs1,799,677 — — 
Total
26,320,206 32,393,385 22,103,357 
v3.22.0.1
INCOME TAXES (Tables)
 12 Months Ended
Dec. 31, 2021
Income Tax Disclosure [Abstract]  
Schedule of Income before Income Tax, Domestic and Foreign
The components of loss before provision for income taxes for the years ended December 31, 2021, 2020, and 2019 are as follows (in thousands):
December 31,
202120202019
Domestic$(101,211)$(156,119)$(59,408)
Foreign— — — 
Loss before income taxes$(101,211)$(156,119)$(59,408)
Schedule of Components of Income Tax Expense (Benefit) The components of the provision for income tax expense for the years ended December 31, 2021, 2020, and 2019 are as follows (in thousands):
December 31,
202120202019
Current:
Federal$— $— $— 
State— 5 6 
Total current— 5 6 
Deferred:
Federal— — — 
State— — — 
Total deferred— — — 
Total provision for income taxes$— $5 $6 
Schedule of Effective Income Tax Rate Reconciliation
The effective tax rate of the Company’s provision (benefit) for income taxes differs from the federal statutory rate as follows:
December 31,
202120202019
Statutory rate21.00 %21.00 %21.00 %
State tax3.15 %3.19 %7.13 %
Foreign income and withholding taxes1.61 %0.41 %0.08 %
Stock-based compensation6.17 %(0.60)%(0.51)%
Change in fair value of warrants0.71 %(11.36)%0.53 %
Other(1.19)%— %(0.04)%
Non-deductible interest expense(2.53)%(1.51)%(2.63)%
Valuation allowance(28.92)%(11.13)%(25.56)%
Total— %— %— %— %
Schedule of Deferred Tax Assets and Liabilities Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2021 and 2020 are as follows (in thousands):
December 31,
20212020
Deferred tax assets:
Net operating losses$92,160 $59,960 
Tax credits741 761 
Depreciable assets604 635 
Operating lease liabilities3,558 — 
Accruals and allowances1,803 575 
Stock-based compensation1,359 83 
Deferred revenue24,734 27,962 
Interest expense1,209 — 
Other3,989 3,035 
Total gross deferred tax assets130,157 93,011 
Less: Valuation allowance(125,082)(91,315)
Net deferred tax assets5,075 1,696 
Deferred tax liabilities:
Amortization of asset retirement obligation(768)(944)
Intangibles(862)(752)
Right-of-use assets(3,445)— 
Total gross deferred tax liabilities(5,075)(1,696)
Net deferred taxes$— $— 
v3.22.0.1
BUSINESS - Narrative (Details)
$ / shares in Units, $ in Thousands
 12 Months Ended
Feb. 01, 2022
USD ($)
Nov. 22, 2021
USD ($)
Apr. 28, 2021
USD ($)
$ / shares
shares
Dec. 31, 2021
USD ($)
$ / shares
Dec. 31, 2020
USD ($)
$ / shares
Dec. 31, 2019
USD ($)
Apr. 27, 2021
$ / shares
Description Of Merger [Abstract]              
Proceeds received     $ 550,322        
Preferred stock, par value (in dollars per share) | $ / shares       $ 0.0001 $ 0.0001   $ 0.00001
Common stock, par value (in dollars per share) | $ / shares       $ 0.0001 $ 0.0001   $ 0.000001
Exchange ratio     4.6432        
Sale of stock, number of shares Issued in transaction (in shares) | shares     22,500,000        
Sale of stock (in dollars per share) | $ / shares     $ 10        
Sale of stock aggregate purchase price     $ 225,000        
Net liabilities     $ 302,200        
Liquidity And Going Concern [Abstract]              
Cash and cash equivalents       $ 747,780 $ 6,942    
Short-term investments       173,000      
Accumulated deficit       509,052 407,841    
Working capital       935,900      
Debt financing coming due within the next 12 months       15,300      
Increase of net loss       101,211 156,124 $ 59,414  
Negative cash flows from operating activities       101,266 33,671 29,678  
Proceeds from public exercises warrant       145,300      
Proceeds from convertible notes       $ 446,827 $ 33,081 $ 63,250  
AlsoEnergy, Inc | Subsequent Event              
Liquidity And Going Concern [Abstract]              
Percent of outstanding shares acquired 100.00%            
Aggregate purchase price $ 695,000            
Cash percentage 75.00%            
2028 Convertible Notes | Convertible Notes              
Liquidity And Going Concern [Abstract]              
Proceeds from convertible notes   $ 445,700          
Energy Storage Systems              
Description Of Business [Abstract]              
Estimated useful life       10 years      
Maximum | Energy Storage Systems              
Description Of Business [Abstract]              
Estimated useful life       20 years      
v3.22.0.1
BUSINESS - Schedule of Reverse Recapitalization (Details) - USD ($)
$ in Thousands
 12 Months Ended
Apr. 28, 2021
Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Cash — STPK trust and working capital cash $ 383,383  
Cash — PIPE (as described below) 225,000  
Less: transaction costs and advisory fees paid (58,061) $ (58,061)
Merger and PIPE financing $ 550,322  
v3.22.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
 3 Months Ended 12 Months Ended 36 Months Ended
Dec. 31, 2021
USD ($)
Sep. 30, 2021
USD ($)
Jun. 30, 2021
USD ($)
Mar. 31, 2021
USD ($)
Dec. 31, 2021
USD ($)
segment
arrangement
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2020
USD ($)
Nov. 22, 2021
USD ($)
Concentration Risk [Line Items]                    
Increase of net loss         $ 101,211,000 $ 156,124,000 $ 59,414,000      
Cost of revenue         126,124,000 40,219,000 20,812,000      
Sales and marketing         $ 19,950,000 14,829,000 17,462,000      
Number of operating segments | segment         1          
Allowance for doubtful accounts $ 100,000       $ 100,000 100,000     $ 100,000  
Deferred incremental costs of obtaining a contract         3,000,000 2,600,000        
Amortization of contract costs 3,900,000       3,900,000 800,000 500,000   800,000  
Impairment cost losses         $ 500,000 100,000 500,000      
Finite-lived intangible asset, useful life         5 years          
Amortization         $ 5,000,000 4,000,000 3,000,000      
Number of types or revenue arrangements | arrangement         2          
Accrual of interest and penalties for uncertain tax positions 0       $ 0 $ 0     0  
Accounting Standards Update [Extensible Enumeration]         Accounting Standards Update 2020-06 [Member]          
2028 Convertible Notes | Convertible Notes                    
Concentration Risk [Line Items]                    
Face amount                   $ 460,000,000.0
Energy Storage Systems                    
Concentration Risk [Line Items]                    
Estimated useful life         10 years          
Internally developed software                    
Concentration Risk [Line Items]                    
Finite-lived intangible asset, useful life         5 years          
Host Customer Arrangements                    
Concentration Risk [Line Items]                    
Incentive period         5 years          
Estimated benefit period         10 years          
Minimum | Host Customer Arrangements                    
Concentration Risk [Line Items]                    
Contract term         5 years          
Minimum | Partnership Arrangements                    
Concentration Risk [Line Items]                    
Contract term         10 years          
Maximum | Energy Storage Systems                    
Concentration Risk [Line Items]                    
Estimated useful life         20 years          
Maximum | Host Customer Arrangements                    
Concentration Risk [Line Items]                    
Contract term         10 years          
Maximum | Partnership Arrangements                    
Concentration Risk [Line Items]                    
Contract term         20 years          
Transfers control of inventory period         1 year          
Accounts Receivable | Customer Concentration Risk | Customer A                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         23.00%          
Accounts Receivable | Customer Concentration Risk | Customer B                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         15.00%          
Accounts Receivable | Customer Concentration Risk | Customer C                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         13.00% 17.00%        
Accounts Receivable | Customer Concentration Risk | Customer D                    
Concentration Risk [Line Items]                    
Concentration risk, percentage           30.00%        
Accounts Receivable | Customer Concentration Risk | Customer E                    
Concentration Risk [Line Items]                    
Concentration risk, percentage           20.00%        
Revenue | Customer Concentration Risk | Customer A                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         11.00%          
Revenue | Customer Concentration Risk | Customer B                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         10.00% 12.00%        
Revenue | Customer Concentration Risk | Customer C                    
Concentration Risk [Line Items]                    
Concentration risk, percentage         10.00% 25.00%        
Retroactive application of recapitalization                    
Concentration Risk [Line Items]                    
Increase of net loss 4,200,000               2,800,000  
Cost of revenue 1,800,000 $ 100,000 $ 0 $ 0   $ 200,000 600,000 $ 900,000 1,700,000  
Sales and marketing $ 2,400,000 $ 800,000 $ 200,000 $ 300,000   $ 800,000 $ 200,000 $ 100,000 $ 1,100,000  
v3.22.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Time periods in errors originated (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended 36 Months Ended
Dec. 31, 2021
Sep. 30, 2021
Jun. 30, 2021
Mar. 31, 2021
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2020
Error Corrections and Prior Period Adjustments Restatement [Line Items]                  
Contract origination costs, net         $ 2,622 $ 2,552 $ 1,302    
Cost of service revenue         126,124 40,219 20,812    
Sales and marketing         $ 19,950 14,829 17,462    
Retroactive application of recapitalization                  
Error Corrections and Prior Period Adjustments Restatement [Line Items]                  
Energy storage systems, net   $ (1,800) $ (1,700) $ (1,700)   (1,700) (1,500) $ (900)  
Contract origination costs, net   (2,400) (1,600) (1,400)   (1,100) (300) (100)  
Cost of service revenue $ 1,800 100 0 0   200 600 900 $ 1,700
Sales and marketing $ 2,400 $ 800 $ 200 $ 300   $ 800 $ 200 $ 100 $ 1,100
v3.22.0.1
REVENUE - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Disaggregation of Revenue [Line Items]      
Total revenue $ 127,371 $ 36,307 $ 17,552
Partnership hardware and service revenue      
Disaggregation of Revenue [Line Items]      
Total revenue 107,135 20,713 4,076
Host customer service revenue      
Disaggregation of Revenue [Line Items]      
Total revenue $ 20,236 $ 15,594 $ 13,476
v3.22.0.1
REVENUE - Remaining Performance Obligations (Details)
$ in Thousands
Dec. 31, 2021
USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Total remaining performance obligations $ 217,797
Service revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Total remaining performance obligations 169,758
Hardware revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Total remaining performance obligations $ 48,039
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Service revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 12.00%
Period expected to be recognized as revenue 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Hardware revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 100.00%
Period expected to be recognized as revenue 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Service revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 50.00%
Period expected to be recognized as revenue 4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Hardware revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 0.00%
Period expected to be recognized as revenue 4 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01 | Service revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 38.00%
Period expected to be recognized as revenue
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01 | Hardware revenue  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Percent Expected to be Recognized as Revenue 0.00%
Period expected to be recognized as revenue
v3.22.0.1
REVENUE - Contract Balances (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Contract With Customer, Liability [Roll Forward]      
Beginning balance $ 52,410 $ 20,728 $ 11,859
Upfront payments received from customers 89,951 40,481 6,698
Upfront or annual incentive payments received 6,614 8,015 8,240
Revenue recognized related to amounts that were included in beginning balance of deferred revenue (33,585) (9,764) (4,830)
Revenue recognized related to deferred revenue generated during the period (77,947) (7,050) (1,239)
Ending balance $ 37,443 $ 52,410 $ 20,728
v3.22.0.1
SHORT-TERM INVESTMENTS (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Cash equivalents:    
Amortized cost $ 127,261  
Cash equivalents 127,261  
Debt securities:    
Amortized cost 173,183  
Unrealized gain 17  
Unrealized Loss (192)  
Debt securities 173,008  
Classified as:    
Cash equivalents 127,261  
Short-term debt securities 173,008 $ 0
Long-term debt securities 0  
Other-than-temporary impairment losses 0  
Corporate debt securities    
Debt securities:    
Amortized cost 42,174  
Unrealized gain 11  
Unrealized Loss (52)  
Debt securities 42,133  
Commercial paper    
Debt securities:    
Amortized cost 20,743  
Unrealized gain 0  
Unrealized Loss 0  
Debt securities 20,743  
U.S. government bonds    
Debt securities:    
Amortized cost 86,265  
Unrealized gain 0  
Unrealized Loss (135)  
Debt securities 86,130  
Certificate of deposits    
Debt securities:    
Amortized cost 21,501  
Unrealized gain 6  
Unrealized Loss 0  
Debt securities 21,507  
Other    
Debt securities:    
Amortized cost 2,500  
Unrealized gain 0  
Unrealized Loss (5)  
Debt securities 2,495  
Money market fund    
Cash equivalents:    
Amortized cost 127,261  
Cash equivalents 127,261  
Classified as:    
Cash equivalents $ 127,261  
v3.22.0.1
FAIR VALUE MEASUREMENTS - Schedule of Financial Instruments Measured at Fair Value (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Cash equivalents:    
Cash equivalents $ 127,261  
Debt securities    
Debt securities 173,008  
Corporate debt securities    
Debt securities    
Debt securities 42,133  
Commercial paper    
Debt securities    
Debt securities 20,743  
U.S. government bonds    
Debt securities    
Debt securities 86,130  
Certificate of deposits    
Debt securities    
Debt securities 21,507  
Other    
Debt securities    
Debt securities 2,495  
Money market fund    
Cash equivalents:    
Cash equivalents 127,261  
Fair Value, Recurring    
Debt securities    
Total financial assets 300,269  
Fair Value, Recurring | Convertible preferred stock warrant liability    
Liabilities    
Convertible preferred stock warrant liability   $ 95,342
Fair Value, Recurring | Corporate debt securities    
Debt securities    
Debt securities 42,133  
Fair Value, Recurring | Commercial paper    
Debt securities    
Debt securities 20,743  
Fair Value, Recurring | U.S. government bonds    
Debt securities    
Debt securities 86,130  
Fair Value, Recurring | Certificate of deposits    
Debt securities    
Debt securities 21,507  
Fair Value, Recurring | Other    
Debt securities    
Debt securities 2,495  
Fair Value, Recurring | Money market fund    
Cash equivalents:    
Cash equivalents 127,261 67
Level 1 | Fair Value, Recurring    
Debt securities    
Total financial assets 127,261  
Level 1 | Fair Value, Recurring | Convertible preferred stock warrant liability    
Liabilities    
Convertible preferred stock warrant liability   0
Level 1 | Fair Value, Recurring | Corporate debt securities    
Debt securities    
Debt securities 0  
Level 1 | Fair Value, Recurring | Commercial paper    
Debt securities    
Debt securities 0  
Level 1 | Fair Value, Recurring | U.S. government bonds    
Debt securities    
Debt securities 0  
Level 1 | Fair Value, Recurring | Certificate of deposits    
Debt securities    
Debt securities 0  
Level 1 | Fair Value, Recurring | Other    
Debt securities    
Debt securities 0  
Level 1 | Fair Value, Recurring | Money market fund    
Cash equivalents:    
Cash equivalents 127,261 67
Level 2 | Fair Value, Recurring    
Debt securities    
Total financial assets 173,008  
Level 2 | Fair Value, Recurring | Convertible preferred stock warrant liability    
Liabilities    
Convertible preferred stock warrant liability   0
Level 2 | Fair Value, Recurring | Corporate debt securities    
Debt securities    
Debt securities 42,133  
Level 2 | Fair Value, Recurring | Commercial paper    
Debt securities    
Debt securities 20,743  
Level 2 | Fair Value, Recurring | U.S. government bonds    
Debt securities    
Debt securities 86,130  
Level 2 | Fair Value, Recurring | Certificate of deposits    
Debt securities    
Debt securities 21,507  
Level 2 | Fair Value, Recurring | Other    
Debt securities    
Debt securities 2,495  
Level 2 | Fair Value, Recurring | Money market fund    
Cash equivalents:    
Cash equivalents 0 0
Level 3 | Fair Value, Recurring    
Debt securities    
Total financial assets 0  
Level 3 | Fair Value, Recurring | Convertible preferred stock warrant liability    
Liabilities    
Convertible preferred stock warrant liability   95,342
Level 3 | Fair Value, Recurring | Corporate debt securities    
Debt securities    
Debt securities 0  
Level 3 | Fair Value, Recurring | Commercial paper    
Debt securities    
Debt securities 0  
Level 3 | Fair Value, Recurring | U.S. government bonds    
Debt securities    
Debt securities 0  
Level 3 | Fair Value, Recurring | Certificate of deposits    
Debt securities    
Debt securities 0  
Level 3 | Fair Value, Recurring | Other    
Debt securities    
Debt securities 0  
Level 3 | Fair Value, Recurring | Money market fund    
Cash equivalents:    
Cash equivalents $ 0 $ 0
v3.22.0.1
FAIR VALUE MEASUREMENTS - Narrative (Details) - Convertible Notes - USD ($)
$ / shares in Units, $ in Millions
Nov. 22, 2021
Dec. 31, 2021
Level 2    
Debt Instrument [Line Items]    
Outstanding principal   $ 447.8
2028 Convertible Notes    
Debt Instrument [Line Items]    
Face amount $ 460.0  
2028 Convertible Notes | Level 2    
Debt Instrument [Line Items]    
Outstanding principal $ 324.8  
Capped Call Options    
Debt Instrument [Line Items]    
Number of shares covered by capped calls (in shares) 15,730,390  
Cap price (in dollars per share) $ 49.6575  
v3.22.0.1
FAIR VALUE MEASUREMENTS - Key Assumptions Used for Valuation (Details)
Dec. 31, 2021
Volatility  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Measurement input 0.650
Risk-free interest rate  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Measurement input 0.001
Expected term (in years)  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Measurement input 1.5
Dividend yield  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Measurement input 0
Discount for lack of marketability  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Measurement input 0.123
v3.22.0.1
FAIR VALUE MEASUREMENTS - Schedule of Changes in Liability for Unobservable Inputs (Details) - Warrant Liability - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance $ 95,342 $ 6,094
Changes in estimated fair value 488 85,623
Assumption of warrant liability upon Merger 302,556 0
Issuance of warrants 0 3,633
Conversion of warrants upon Merger (60,568) 0
Exchange of warrants (168,647) 0
Exercise of warrants (169,171) (8)
Ending balance $ 0 $ 95,342
v3.22.0.1
GOODWILL AND INTANGIBLE ASSETS, NET - Goodwill consists (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]    
Goodwill $ 1,625 $ 1,625
Effect of foreign currency translation 116 114
Total goodwill $ 1,741 $ 1,739
v3.22.0.1
GOODWILL AND INTANGIBLE ASSETS, NET - Intangible assets, net (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Acquired Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 30,206 $ 23,045  
Less: Accumulated amortization (16,276) (10,993)  
Add: Currency translation adjustment 36 35  
Total intangible assets, net 13,966 12,087  
Amortization expense for intangible assets 5,300 4,500 $ 3,100
Developed technology      
Acquired Finite-Lived Intangible Assets [Line Items]      
Intangible assets 500 500  
Internally developed software      
Acquired Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 29,706 $ 22,545  
v3.22.0.1
LEASES - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Lessee, Lease, Description [Line Items]      
Lessee renewal term 5 years    
Operating lease rent expense $ 1.3 $ 0.8 $ 1.2
Cash paid for operating lease liabilities $ 0.5 $ 0.7 $ 0.9
Minimum      
Lessee, Lease, Description [Line Items]      
Lease term 3 years    
Maximum      
Lessee, Lease, Description [Line Items]      
Lease term 8 years    
v3.22.0.1
LEASES - Operating Lease Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Leases [Abstract]    
2022 $ 1,818  
2023 2,473  
2024 2,239  
2025 2,109  
2026 2,172  
Thereafter 4,937  
Total lease payments 15,748  
Less: imputed interest (2,325)  
Operating lease liability $ 13,423 $ 390
v3.22.0.1
LEASES - Summary of Lease Information (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Leases [Abstract]    
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Other current liabilities (includes $306 and $399 due to related parties as of December 31, 2021 and December 31, 2020, respectively) Other current liabilities (includes $306 and $399 due to related parties as of December 31, 2021 and December 31, 2020, respectively)
Current portion of operating lease liabilities included within other current liabilities $ 1,240 $ 333
Lease liability, noncurrent 12,183 57
Total operating lease liability future lease payments $ 13,423 $ 390
Weighted average remaining operating lease term (in years) 6 years 8 months 12 days 9 months 18 days
Weighted average discount rate 4.50% 11.30%
v3.22.0.1
ASSET RETIREMENT OBLIGATION (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Beginning balance at January 1, $ 4,137 $ 5,759
Asset retirement obligation 0 771
Settlement of asset retirement obligation 0 (1,375)
Retirement cost revaluation (231) (1,235)
Accretion expense 229 217
Ending balance at December 31, $ 4,135 $ 4,137
v3.22.0.1
ENERGY STORAGE SYSTEMS, NET - Schedule of Energy Storage Systems, Net (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Property, Plant and Equipment [Line Items]    
Less: accumulated depreciation $ (45,250) $ (33,389)
Total energy storage systems, net 106,114 123,703
Energy storage systems placed into service    
Property, Plant and Equipment [Line Items]    
Total energy storage systems, gross 143,592 144,425
Energy storage systems not yet placed into service    
Property, Plant and Equipment [Line Items]    
Total energy storage systems, gross $ 7,772 $ 12,667
v3.22.0.1
ENERGY STORAGE SYSTEMS, NET - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Property, Plant and Equipment [Abstract]      
Depreciation expense $ 14.4 $ 13.9 $ 9.7
v3.22.0.1
BALANCE SHEET COMPONENTS - Inventory (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Work in process inventory $ 20,582 $ 15,296
Batteries 2,138 5,547
Inventory, net $ 22,720 $ 20,843
v3.22.0.1
BALANCE SHEET COMPONENTS - Other Current Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Deferred costs with suppliers $ 13,744 $ 6,204
Prepaid expenses 3,137 698
Utility program deposits 353 891
Due from related parties 213 123
Other 1,194 4
Total other current assets $ 18,641 $ 7,920
v3.22.0.1
BALANCE SHEET COMPONENTS - Other Noncurrent Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Prepaid warranties and maintenance $ 15,991 $ 1,088
Receivable from SPEs 3,565 3,583
Deferred SPAC costs 0 1,256
Self-generation incentive program deposits 940 1,036
Total equity method investments 1,924 744
Net proceeds to pay cost 0 73
Property and equipment, net 512 44
Other 1,599 458
Other noncurrent assets $ 24,531 $ 8,282
v3.22.0.1
BALANCE SHEET COMPONENTS - Accrued Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Accrued payables $ 25,062 $ 9,799
Accrued interest – notes payable 344 6,149
Other accrued liabilities 587 124
Total accrued liabilities $ 25,993 $ 16,072
v3.22.0.1
BALANCE SHEET COMPONENTS - Other Current Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
System advances $ 267 $ 640
Current portion of operating lease liabilities included within other current liabilities 1,240 333
Due to related parties 306 399
Other 0 217
Total other current liabilities $ 1,813 $ 1,589
v3.22.0.1
NOTES PAYABLE - Revolving Loan Due to SPE Member (Details) - Line of Credit - Revolving Loan Due To SPE Member - USD ($)
$ in Millions
 1 Months Ended
Aug. 31, 2020
May 31, 2020
Apr. 30, 2017
Dec. 31, 2020
Jan. 01, 2020
Debt Instrument [Line Items]          
Total capacity   $ 35.0     $ 45.0
Fixed interest rate, annual   14.00%     10.00%
Period threshold for interest rate   9 months      
Percent of capacity usage for financing of hardware purchases 70.00% 85.00% 100.00%    
Outstanding balance       $ 7.4  
v3.22.0.1
NOTES PAYABLE - Term Loan Due to SPE Member (Details) - Term Loan Due To SPE Member - Term Loan - USD ($)
$ in Millions
 1 Months Ended
May 31, 2020
Jan. 01, 2020
Dec. 31, 2018
Debt Instrument [Line Items]      
Face amount     $ 13.3
Fixed interest rate, annual   12.50%  
Final balloon payment   $ 3.0  
Repayment of debt $ 5.9    
v3.22.0.1
NOTES PAYABLE - Term Loan Due to Former Non-Controlling Interest Holder (Details) - USD ($)
$ in Millions
 1 Months Ended
Apr. 30, 2021
May 31, 2020
Jun. 30, 2018
Dec. 31, 2020
Debt Instrument [Line Items]        
Payment to acquire noncontrolling interest     $ 8.1  
Term Loan Due To Former Non-Controlling Interest Holder | Term Loan        
Debt Instrument [Line Items]        
Fixed interest rate, quarterly     4500.00%  
Fixed interest rate, annual     18.00%  
Prepaid principal and interest   $ 1.5    
Prepaid principal   $ 1.0    
Warrants issued (in shares)   400,000    
Unamortized discount   $ 0.2    
Long-term debt securities       $ 5.8
Debt instrument, prepayment penalties $ 2.6      
v3.22.0.1
NOTES PAYABLE - 2020 and 2021 Credit Agreements (Details) - Line of Credit - USD ($)
$ in Millions
 1 Months Ended
Apr. 30, 2021
Jan. 31, 2021
May 31, 2020
Dec. 31, 2021
Dec. 31, 2020
2020 Credit Agreement          
Debt Instrument [Line Items]          
Proceeds from credit agreement     $ 25.0    
Fixed interest rate, annual     12.00%    
Fixed interest rate, paid in cash     8.00%    
Fixed interest rate, added back to principal     4.00%    
Outstanding balance         $ 25.6
Prepayment penalties $ 1.4        
2021 Credit Agreement          
Debt Instrument [Line Items]          
Proceeds from credit agreement   $ 1.8      
Fixed interest rate, annual   5.45%      
Outstanding balance       $ 1.9  
Total capacity   $ 2.7      
v3.22.0.1
NOTES PAYABLE - Schedule of Outstanding Debt (Details) - Notes Payable
$ in Thousands
Dec. 31, 2021
USD ($)
Debt Instrument [Line Items]  
Outstanding principal $ 1,902
Unamortized discount (215)
Carrying value of debt $ 1,687
v3.22.0.1
CONVERTIBLE PROMISSORY NOTES - Narrative (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Nov. 22, 2021
USD ($)
day
$ / shares
Nov. 19, 2021
USD ($)
$ / shares
Apr. 28, 2021
USD ($)
shares
Jan. 31, 2021
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Debt Instrument [Line Items]              
Proceeds from convertible notes         $ 446,827 $ 33,081 $ 63,250
Debt conversion, converted instrument, shares issued (in shares) | shares     10,921,548        
Loss on extinguishment of debt         5,064 0 $ 0
Capped Call Options              
Debt Instrument [Line Items]              
Cost of capped calls   $ 66,700          
Initial strike price (in dollars per share) | $ / shares   $ 29.2428          
Cap price (in dollars per share) | $ / shares   $ 49.6575          
Convertible Notes              
Debt Instrument [Line Items]              
Convertible notes payable         0 $ 67,600  
Convertible Notes | Q1 2021 Convertible Notes              
Debt Instrument [Line Items]              
Proceeds from convertible notes       $ 1,100      
Convertible Notes | Convertible Promissory Notes              
Debt Instrument [Line Items]              
Debt conversion, converted instrument, amount     $ 77,700        
Debt instrument, increase, accrued interest     $ 7,700        
Loss on extinguishment of debt         1,100    
Convertible Notes | 2028 Convertible Notes              
Debt Instrument [Line Items]              
Proceeds from convertible notes $ 445,700            
Unamortized discount 12,420            
Face amount $ 460,000            
Fixed interest rate, annual 0.50%            
Conversion ratio 0.0341965            
Conversion price (in dollars per share) | $ / shares $ 29.2428            
Redemption price, percentage 100.00%            
Term 7 years            
Debt issuance costs $ 1,871            
Effective interest rate 5.96%            
Outstanding principal         $ 460,000    
Equity component $ 135,200            
Convertible Notes | 2028 Convertible Notes | Debt Instrument, Redemption, Period One              
Debt Instrument [Line Items]              
Conversion price, percentage 130.00%            
Convertible Notes | 2028 Convertible Notes | Debt Instrument, Redemption, Period Two              
Debt Instrument [Line Items]              
Threshold trading days | day 20            
Convertible Notes | Capped Call Options              
Debt Instrument [Line Items]              
Cap price (in dollars per share) | $ / shares $ 49.6575            
v3.22.0.1
CONVERTIBLE PROMISSORY NOTES - Allocated To Debt And Equity Components Based (Details) - 2028 Convertible Notes - Convertible Notes - USD ($)
$ in Thousands
Dec. 31, 2021
Nov. 22, 2021
Debt Instrument [Line Items]    
Unamortized discount   $ 12,420
Debt issuance costs   1,871
Total $ 143,458 14,291
Equity Component    
Initial Purchaser’s Debt Discount   3,650
Debt Issuance Costs   550
Total   4,200
Debt Component    
Initial Purchaser’s Debt Discount   8,770
Debt Issuance Costs   1,321
Total   $ 10,091
v3.22.0.1
CONVERTIBLE PROMISSORY NOTES - Outstanding 2028 Convertible Notes (Details) - Convertible Notes - 2028 Convertible Notes - USD ($)
$ in Thousands
Dec. 31, 2021
Nov. 22, 2021
Debt Instrument [Line Items]    
Outstanding principal $ 460,000  
Unamortized discount (143,458) $ (14,291)
Carrying value of debt $ 316,542  
v3.22.0.1
CONVERTIBLE PROMISSORY NOTES - Interest Expense Recognized Related to Convertible Note (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Debt Instrument [Line Items]      
Non-cash interest expense, including interest expenses associated with debt issuance costs $ 9,648 $ 10,044 $ 4,759
2028 Convertible Notes | Convertible Notes      
Debt Instrument [Line Items]      
Contractual interest expense 249    
Non-cash interest expense, including interest expenses associated with debt issuance costs 1,812    
Interest expense $ 2,061    
v3.22.0.1
WARRANTS (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Sep. 20, 2021
Jun. 24, 2021
Apr. 28, 2021
Apr. 07, 2021
Aug. 20, 2020
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Jun. 25, 2021
Class of Warrant or Right [Line Items]                  
Warrants outstanding (in shares)     50,207,439            
Conversion of securities into common stock (in shares)     2,759,970            
(Gain) loss from fair value adjustment     $ (100,900)     $ (3,424) $ 84,455 $ (1,493)  
Conversion of securities into common stock     $ 60,600            
Sale of stock, number of shares Issued in transaction (in shares)     22,500,000            
Number of shares called from each warrant (in shares)         1        
Exercise Price (in dollars per share)       $ 0.01          
Number of shares called from exchange of warrants (in shares)       350,000          
Warrants and rights outstanding         $ 302,600        
Issued irrevocable notice redemption (in shares) 12,786,129                
Cash net of broker fees           145,300      
Issuance of common stock warrants for services       $ 9,200   $ 9,183      
Legacy Stem Warrants                  
Class of Warrant or Right [Line Items]                  
Warrants outstanding (in shares)           23,673      
Public Warrants                  
Class of Warrant or Right [Line Items]                  
Sale of stock, number of shares Issued in transaction (in shares)         12,786,168        
Exercise Price (in dollars per share) $ 11.50       $ 11.50        
Number of shares called from exchange of warrants (in shares) 12,638,723                
Warrants and rights outstanding         $ 185,900        
Cash net of broker fees $ 145,300                
Net gain revaluation and redemption 134,900                
Gain on redemption of warrants $ 2,100                
Private Warrants                  
Class of Warrant or Right [Line Items]                  
Warrants outstanding (in shares)           0     7,181,134
(Gain) loss from fair value adjustment   $ 52,000              
Number of shares called from exchange of warrants (in shares)         7,181,134       4,683,349
Warrants and rights outstanding         $ 116,700        
v3.22.0.1
COMMON STOCK (Details) - shares
Dec. 31, 2021
May 31, 2021
Dec. 31, 2020
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 50,477,700    
Outstanding RSUs      
Class of Stock [Line Items]      
RSUs outstanding, ending of period (in shares) 1,799,677   0
2021 Equity Incentive Plan      
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 23,722,254 23,722,254  
2021 Equity Incentive Plan | Outstanding RSUs      
Class of Stock [Line Items]      
RSUs outstanding, ending of period (in shares) 1,801,831    
Shares reserved for warrants      
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 23,673    
Options issued and outstanding      
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 8,766,466    
Shares available for future issuance under equity incentive plan      
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 20,844,788    
Conversion of 2028 Convertible Notes      
Class of Stock [Line Items]      
Reserved shares of common stock for issuance ( in shares) 20,842,773    
v3.22.0.1
STOCK-BASED COMPENSATION - Narrative (Details)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
May 31, 2021
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Options outstanding (in shares) | shares 8,766,466 11,065,658    
Reserved shares of common stock for issuance ( in shares) | shares 50,477,700      
Options granted, weighted-average grant date fair value (in dollars per share) | $ / shares $ 18.84 $ 3.79 $ 1.58  
Options exercised, intrinsic value $ 56,100 $ 1,100 $ 100  
Shares issued from net settlement (in shares) | shares 1,054,594      
Options converted from net settlement (in shares) | shares 1,648,463      
Payments for taxes related to net share settlement of stock options $ 12,622 0 0  
Remaining unrecognized stock-based compensation expense 21,100      
Total stock-based compensation expense 13,546 4,542 1,531  
Research and development        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total stock-based compensation expense 2,367 $ 1,211 $ 901  
Research and development | Internally developed software        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Total stock-based compensation expense $ 1,200      
2009 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Options outstanding (in shares) | shares 7,754,811      
2021 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Options outstanding (in shares) | shares 1,075,635      
Reserved shares of common stock for issuance ( in shares) | shares 23,722,254     23,722,254
Stock Options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Exercise price as a percentage of fair value 100.00%      
Exercise price as a percentage of fair value for shareholders owning specified minimum amount 110.00%      
Significant shareholder threshold used for determining exercise price 10.00%      
Exercise period 10 years      
Payments for taxes related to net share settlement of stock options $ 12,600      
Weighted average period for recognition of stock-based compensation expense 3 years 2 months 12 days      
Stock Options | Share-based Payment Arrangement, Tranche One        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting percentage 25.00%      
Vesting period 1 year      
Stock Options | Share-based Payment Arrangement, Tranche Two        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting percentage 2.08%      
Vesting period 3 years      
RSU        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Right to receive, conversion ratio 1      
Fair value of grants in period $ 64,800      
RSUs vested (in shares) | shares 0      
Remaining unrecognized stock-based compensation expense $ 56,500      
Weighted average period for recognition of stock-based compensation expense 4 years 10 months 24 days      
RSU | 2009 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting percentage 25.00%      
Vesting period 4 years      
RSU | 2021 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting percentage 20.00%      
Vesting period 7 years      
v3.22.0.1
STOCK-BASED COMPENSATION - Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Number of Options Outstanding    
Options outstanding, beginning of period (in shares) 11,065,658  
Options granted (in shares) 1,079,583  
Options exercised (in shares) (3,235,713)  
Options forfeited (in shares) (129,102)  
Options expired (in shares) (13,960)  
Options outstanding, end of period (in shares) 8,766,466 11,065,658
Options vested and exercisable (in shares) 6,298,675  
Weighted- Average Exercise Price Per Share    
Options outstanding, weighted average exercise price (in dollars per share) $ 6.01 $ 2.61
Options granted, weighted average exercise price (in dollars per share) 28.73  
Options exercised, weighted average exercise price (in dollars per share) 1.64  
Options forfeited, weighted average exercise price (in dollars per share) 15.18  
Options expired, weighted average exercise price (in dollars per share) 0.53  
Options vested and exercisable, weighted-average exercise price (in dollars per share) $ 2.61  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]    
Weighted average remaining contractual life, options outstanding 7 years 1 month 6 days 7 years 2 months 12 days
Weighted average remaining contractual life, options vested and exercisable 6 years 4 months 24 days  
Aggregate intrinsic value, options outstanding $ 123,570 $ 46,516
Aggregate intrinsic value, options vested and exercisable $ 103,100  
Previously Reported    
Number of Options Outstanding    
Options outstanding, beginning of period (in shares) 51,379,939  
Options outstanding, end of period (in shares)   51,379,939
Weighted- Average Exercise Price Per Share    
Options outstanding, weighted average exercise price (in dollars per share)   $ 0.56
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]    
Weighted average remaining contractual life, options outstanding   7 years 2 months 12 days
Aggregate intrinsic value, options outstanding   $ 46,516
Retroactive application of recapitalization    
Number of Options Outstanding    
Options outstanding, beginning of period (in shares) (40,314,281)  
Options outstanding, end of period (in shares)   (40,314,281)
Weighted- Average Exercise Price Per Share    
Options outstanding, weighted average exercise price (in dollars per share)   $ 2.05
v3.22.0.1
STOCK-BASED COMPENSATION - Assumptions in Estimating Option Fair Value (Details) - Stock Options
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility 74.00% 71.41% 69.10%
Risk-free interest rate 1.06% 0.49% 2.47%
Expected term (years) 6 years 2 months 23 days 5 years 9 months 25 days 5 years 9 months 29 days
Dividend yield 0.00% 0.00% 0.00%
v3.22.0.1
STOCK-BASED COMPENSATION - RSU Activity (Details) - RSU - $ / shares
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Number of RSUs Outstanding    
RSUs outstanding, ending of period (in shares) 1,799,677 0
RSUs granted (in shares) 1,801,831  
RSUs vested (in shares) 0  
RSUs forfeited (in shares) (2,154)  
Weighted- Average Grant Date Fair Value Per Share    
RSUs outstanding, weighted average grant date fair value (in dollars per share) $ 36.0 $ 0
RSUs granted, weighted average grant date fair value (in dollars per share) 36.0  
RSUs vested, weighted average grant date fair value (in dollars per share) 0  
RSUs forfeited, weighted average grant date fair value (in dollars per share) $ 26.1  
v3.22.0.1
STOCK-BASED COMPENSATION - Stock-Based Compensation Expense (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total stock-based compensation expense $ 13,546 $ 4,542 $ 1,531
Sales and marketing      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total stock-based compensation expense 1,723 396 364
Research and development      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total stock-based compensation expense 2,367 1,211 901
General and administrative      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total stock-based compensation expense $ 9,456 $ 2,935 $ 266
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Assets and Liabilities of Consolidated VIE (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Variable Interest Entity [Line Items]    
Energy storage systems, net $ 106,114 $ 123,703
Deferred revenue, current portion 9,158 36,942
Deferred revenue, noncurrent 28,285 15,468
Variable Interest Entity, Primary Beneficiary    
Variable Interest Entity [Line Items]    
Energy storage systems, net 649 1,463
Deferred revenue, current portion 283 283
Deferred revenue, noncurrent 753 1,047
Other liabilities $ 159 $ 239
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Narrative (Details)
$ in Millions
 12 Months Ended 29 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Jun. 30, 2017
company
Mar. 31, 2020
service_station
Variable Interest Entity [Line Items]          
Number of companies formed | company       3  
Depreciation expense $ 14.4 $ 13.9 $ 9.7    
Variable Interest Entity, Not Primary Beneficiary          
Variable Interest Entity [Line Items]          
Interest expense 8.5 6.9 5.8    
Revenues 16.9 12.8 8.8    
Depreciation expense 12.8 11.8 7.1    
SPV II, SPV III, And SPV IV | Variable Interest Entity, Not Primary Beneficiary          
Variable Interest Entity [Line Items]          
Earnings from equity method investments $ 0.1 $ 0.1 $ 0.2    
COPEC | Variable Interest Entity, Not Primary Beneficiary | CHILE          
Variable Interest Entity [Line Items]          
Number of service stations | service_station         650
COPEC | Variable Interest Entity, Not Primary Beneficiary | South America, Central America, And United States          
Variable Interest Entity [Line Items]          
Number of service stations | service_station         2,500
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Equity Method Investments (Details) - Variable Interest Entity, Not Primary Beneficiary
Dec. 31, 2021
Dec. 31, 2020
SPV II    
Variable Interest Entity [Line Items]    
Initial ownership 49.00%  
SPV II | Class A    
Variable Interest Entity [Line Items]    
Stem’s interest 100.00%  
Distribution percentage, parent 10.00%  
SPV II | Class B    
Variable Interest Entity [Line Items]    
Distribution percentage 90.00%  
SPV III    
Variable Interest Entity [Line Items]    
Initial ownership   50.00%
SPV III | Class A    
Variable Interest Entity [Line Items]    
Distribution percentage 80.00%  
Distribution percentage, parent 50.00%  
SPV III | Class B    
Variable Interest Entity [Line Items]    
Stem’s interest 100.00%  
Distribution percentage 20.00%  
Distribution percentage, parent 100.00%  
SPV IV    
Variable Interest Entity [Line Items]    
Initial ownership 50.00%  
SPV IV | Class A    
Variable Interest Entity [Line Items]    
Distribution percentage 97.50%  
SPV IV | Class B    
Variable Interest Entity [Line Items]    
Stem’s interest 100.00%  
Distribution percentage, parent 2.50%  
COPEC    
Variable Interest Entity [Line Items]    
Initial ownership 49.00%  
COPEC | Class A    
Variable Interest Entity [Line Items]    
Stem’s interest 100.00%  
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Investment in Unconsolidated SPE (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Class of Warrant or Right [Line Items]    
Total equity method investments $ 1,924 $ 744
Variable Interest Entity, Not Primary Beneficiary    
Class of Warrant or Right [Line Items]    
Total equity method investments 1,924 744
SPV II | Variable Interest Entity, Not Primary Beneficiary    
Class of Warrant or Right [Line Items]    
Total equity method investments 0 0
SPV III | Variable Interest Entity, Not Primary Beneficiary    
Class of Warrant or Right [Line Items]    
Total equity method investments 421 487
SPV IV | Variable Interest Entity, Not Primary Beneficiary    
Class of Warrant or Right [Line Items]    
Total equity method investments 291 257
COPEC | Variable Interest Entity, Not Primary Beneficiary    
Class of Warrant or Right [Line Items]    
Total equity method investments $ 1,212 $ 0
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Financing Obligations Associated (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Variable Interest Entity [Line Items]    
Financing obligation, current portion $ 15,277 $ 14,914
Financing obligation, noncurrent 73,204 73,128
Variable Interest Entity, Not Primary Beneficiary    
Variable Interest Entity [Line Items]    
Financing obligation, current portion 15,277 14,914
Financing obligation, noncurrent $ 73,204 $ 73,128
v3.22.0.1
SPECIAL PURPOSE ENTITIES - Carrying Value of Energy Storage System Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Variable Interest Entity [Line Items]    
Energy storage systems, net $ 106,114 $ 123,703
Deferred revenue, current portion 9,158 36,942
Deferred revenue, noncurrent 28,285 15,468
Variable Interest Entity, Not Primary Beneficiary    
Variable Interest Entity [Line Items]    
Energy storage systems, net 92,426 91,593
Deferred revenue, current portion 4,417 3,713
Deferred revenue, noncurrent 10,835 8,265
Other liabilities $ 3,586 $ 3,178
v3.22.0.1
NET LOSS PER SHARE - Basic and diluted net loss per share (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Numerator - Basic and Diluted:      
Net loss $ (101,211) $ (156,124) $ (59,414)
Less: Deemed Dividend 0 (9,484) (5,353)
Net income (loss) attributable to common stockholders, basic (101,211) (165,608) (64,767)
Net income (loss) attributable to common stockholders, diluted $ (101,211) $ (165,608) $ (64,767)
Denominator:      
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic (in shares) 105,561,139 40,064,087 42,811,383
Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, diluted (in shares) 105,561,139 40,064,087 42,811,383
Net loss per share attributable to common shareholders, basic (in dollars per share) $ (0.96) $ (4.13) $ (1.51)
Net loss per share attributable to common shareholders, diluted (in dollars per share) $ (0.96) $ (4.13) $ (1.51)
v3.22.0.1
NET LOSS PER SHARE - Antidilutive securities (Details) - shares
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 26,320,206 32,393,385 22,103,357
Outstanding Pre-Merger Convertible Promissory Notes      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 0 10,495,111 5,202,697
Outstanding 2028 Convertible Notes      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 15,730,390 0 0
Outstanding stock options      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 8,766,466 11,065,658 9,227,850
Outstanding warrants      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 23,673 10,832,616 7,672,810
Outstanding RSUs      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potentially dilutive shares (in shares) 1,799,677 0 0
v3.22.0.1
INCOME TAXES - Components Of Income Before Income Taxes (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Income Tax Disclosure [Abstract]      
Domestic $ (101,211) $ (156,119) $ (59,408)
Foreign 0 0 0
Income (loss) before income taxes $ (101,211) $ (156,119) $ (59,408)
v3.22.0.1
INCOME TAXES - Narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Income Tax Contingency [Line Items]      
Income tax expense $ 0 $ 5 $ 6
Valuation allowance 125,082 91,315  
Uncertain tax positions 700 800  
Domestic Tax Authority      
Income Tax Contingency [Line Items]      
NOL carryforwards 300,800 199,800  
Domestic Tax Authority | Research Tax Credit Carryforward      
Income Tax Contingency [Line Items]      
Tax credit carryforward 700 700  
State and Local Jurisdiction      
Income Tax Contingency [Line Items]      
NOL carryforwards 274,600 200,500  
State and Local Jurisdiction | Research Tax Credit Carryforward      
Income Tax Contingency [Line Items]      
Tax credit carryforward 0 100  
Tax credit carryforward, subject to expiration 700 700  
Foreign Tax Authority      
Income Tax Contingency [Line Items]      
NOL carryforwards $ 9,000 $ 0  
v3.22.0.1
INCOME TAXES - Components Of Income Tax Expense (Benefit) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Current:      
Federal $ 0 $ 0 $ 0
State 0 5 6
Total current 0 5 6
Deferred:      
Federal 0 0 0
State 0 0 0
Total deferred 0 0 0
Income tax expense $ 0 $ 5 $ 6
v3.22.0.1
INCOME TAXES - Provision (Benefit) Of Income Taxes Federal Statutory Rate (Details)
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Income Tax Disclosure [Abstract]      
Statutory rate 21.00% 21.00% 21.00%
State tax 3.15% 3.19% 7.13%
Foreign income and withholding taxes 1.61% 0.41% 0.08%
Stock-based compensation 6.17% (0.60%) (0.51%)
Change in fair value of warrants 0.71% (11.36%) 0.53%
Other (1.19%) 0.00% (0.04%)
Non-deductible interest expense (2.53%) (1.51%) (2.63%)
Valuation allowance (28.92%) (11.13%) (25.56%)
Total 0.00% 0.00% 0.00%
v3.22.0.1
INCOME TAXES- Deferred Tax Assets And Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Deferred tax assets:    
Net operating losses $ 92,160 $ 59,960
Tax credits 741 761
Depreciable assets 604 635
Operating lease liabilities 3,558 0
Accruals and allowances 1,803 575
Stock-based compensation 1,359 83
Deferred revenue 24,734 27,962
Interest expense 1,209 0
Other 3,989 3,035
Total gross deferred tax assets 130,157 93,011
Less: Valuation allowance (125,082) (91,315)
Net deferred tax assets 5,075 1,696
Deferred tax liabilities:    
Amortization of asset retirement obligation (768) (944)
Intangibles (862) (752)
Right-of-use assets (3,445) 0
Total gross deferred tax liabilities (5,075) (1,696)
Net deferred taxes $ 0 $ 0
v3.22.0.1
EMPLOYER RETIREMENT PLAN (Details) - USD ($)
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]      
Employer match amount $ 0 $ 0 $ 0
Minimum      
Defined Contribution Plan Disclosure [Line Items]      
Defer compensation, percentage 1.00%    
Maximum      
Defined Contribution Plan Disclosure [Line Items]      
Defer compensation, percentage 75.00%    
v3.22.0.1
SUBSEQUENT EVENTS (Details) - Subsequent Event - AlsoEnergy, Inc
$ in Millions
Feb. 01, 2022
USD ($)
Subsequent Event [Line Items]  
Percent of outstanding shares acquired 100.00%
Aggregate purchase price $ 695.0
Cash percentage 75.00%
Common Stock  
Subsequent Event [Line Items]  
Share percentage 25.00%