Nature of Operations and Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2022
Accounting Policies [Abstract]
Nature of Operations and Summary of Significant Accounting Policies	Nature of Operations and Summary of Significant Accounting Policies Nature of Operations Eos Energy Enterprises, Inc. (the “Company” or "Eos") designs, develops, manufactures, and sells innovative energy storage solutions for utility-scale microgrid, and commercial & industrial (“C&I”) applications. Eos has developed a broad range of intellectual property with multiple patents ranging from the unique battery chemistry, mechanical product design, energy block configuration and software operating system (“Battery Management System” or “BMS”). The BMS software uses proprietary, Eos-developed algorithms and includes ambient and battery temperature sensors, as well as voltage and electrical current sensors for the electrical strings and the system. Eos focuses on developing and selling safe, reliable, long-lasting and low-cost turn-key alternating current (“AC”) integrated systems using Eos’ direct current (“DC”) battery energy storage system. The Company has a manufacturing facility in Turtle Creek, Pennsylvania to produce DC energy blocks with an integrated BMS. The Company’s primary applications focus on integrating battery storage solutions with: (1) renewable energy systems that are connected to the utility power grid; (2) renewable energy systems that are not connected to the utility power grid; (3) energy systems utilized to relieve congestion; and (4) storage systems to assist C&I customers in reducing their peak energy usage or participating in the utilities ancillary and demand response markets. The Company’s major market is North America with opportunistic growth opportunities in Europe, Oceania, Africa, and Asia. Unless the context otherwise requires, the use of the terms “Eos,” “the Company,” “we,” “us,” and “our” in these notes to the unaudited condensed consolidated financial statements refers to Eos Energy Enterprises, Inc. and its consolidated subsidiaries. Liquidity and Going Concern Under U.S. GAAP, the Company is required to perform a two-step analysis of its ability to continue as a going concern: It must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued or available to be issued (Step 1). If the Company concludes that substantial doubt is raised, it is also required to consider whether the Company’s plans alleviate the substantial doubt (Step 2). The Company continues to scale its operations, including deploying additional capital for capacity expansion to meet current customer demand. To date, the Company has incurred significant recurring losses and net operating cash outflows from operations. Operating expenses consist primarily of costs related to the Company’s research and development, sales activities, and recurring general and administrative expenses. Management and the Company’s Board of Directors expect the Company will eventually reach a scale of profitability through the sale of battery energy storage systems and other complementary products and services, and therefore, the Company believes the current stage of the Company’s lifecycle justifies continued intensive investment in the development and launch of products. Accordingly, the Company expects to continue to incur significant losses and net operating cash outflows from operations for the foreseeable future and to continue to require additional capital to fund the Company’s operations and obligations as they become due, including funding that is necessary to continue to scale up the Company’s operations to allow for the delivery of backlog, to secure additional order opportunities for its battery storage systems, and to continue to invest in research and development. As of September 30, 2022, the Company had total assets of $138,481, including cash, cash equivalents and restricted cash of $51,047 (refer to Note 4, Cash, Cash Equivalents and Restricted Cash), total liabilities of $226,820, which includes the total amounts owed on the Company’s outstanding convertible notes payable of $78,743 and long-term debt of $84,775 (refer to Note 12, Borrowings) and a total accumulated deficit of $589,727, which is primarily attributable to the significant recurring losses the Company has accumulated since inception. The Company used cash in operating activities of $159,129 for the nine months ended September 30, 2022. The Company has historically relied on outside capital to fund its cost structure and expects this reliance to continue for the foreseeable future until the Company reaches profitability through its planned revenue generating activities. During the third quarter of 2022, the Company obtained the following additional financing: (a) the Company borrowed $94,681 under a Senior Secured Term Loan agreement (the “Term Loan”) to fund the Company’s manufacturing capacity, repay an existing outstanding note, and for general corporate purposes; (b) the Company borrowed an additional $4,216 under the equipment financing facility with Trinity Capital, Inc.; and (c) the Company entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”) with respect to an at-the-market offering program. Under the at-the-market-offering program, the Company may offer and sell, from time to time at its sole discretion, shares of its common stock, having an aggregate offering price up to $100,000 through Cowen as sales agent and/or principal. The Company will pay Cowen a commission equal to 3.0% of the gross sales proceeds of any shares of the Company’s common stock sold through Cowen. In the third quarter, under this at-the-market program, the Company issued and sold a total of 12,067,575 shares and raised $30,040 ($29,139 net of commissions) at an average selling price of $2.49 per share. The Term Loan agreement contains customary affirmative and negative covenants, which limit the Company’s and its subsidiaries’ ability to incur indebtedness, make restricted payments, including cash dividends on its common stock, make certain investments, loans and advances, enter into mergers and acquisitions, sell, assign, transfer or otherwise dispose of its assets, enter into transactions with its affiliates and engage in sale and leaseback transactions, among other restrictions (refer to Note 12, Borrowings). The Company was in compliance with all Term Loan covenants as of September 30, 2022. In the second quarter of 2022, the Company entered into a $200,000 common stock Standby Equity Purchase Agreement (“SEPA”) with YA II PN, Ltd. an affiliate of Yorkville Advisors, which was subsequently amended on June 13, 2022. The SEPA gives the Company the right, but not the obligation, to sell up to $200,000 of common equity to Yorkville at times of the Company’s choosing during the two-year term of the agreement. The SEPA provides for shares to be issued to Yorkville at a discounted price of 97.0% of the 3-day volume-weighted average price following notification to Yorkville that the Company seeks to draw upon the facility (refer to Note 11, Related Party Transactions and Note 12, Borrowings). Through the date of this filing, funds raised under the SEPA were $12,500; the Company did not utilize the SEPA in the third quarter. As previously reported, the Company has moved through Part I of the application under the U.S. Department of Energy’s Loan Guarantee Solicitation for Applications for Renewable Energy Projects and Efficient Energy Projects (the “DOE Loan Program”) and submitted an application under Part II of the loan program in May 2022. In September 2022, the Company was invited to the due diligence stage of the DOE Loan Program. During this stage, the Company and the DOE will work to negotiate a term sheet setting out the principal terms and conditions of the loan. This work provides the DOE the foundation to advance the loan towards a conditional commitment. However, the DOE invitation to the due diligence stage is not an assurance that the DOE will offer a conditional commitment, or that the Company will secure a loan under the DOE Loan Program. The Company is seeking additional capital through securities offerings, other financing arrangements and grants to raise additional funding to support its operations. There can be no assurance that the Company will be able to utilize the full value under the Sales Agreement with Cowen, utilize the SEPA to its full $200,000 capacity, successfully complete the DOE Loan Program, or otherwise be able to obtain new funding from other sources on terms acceptable to the Company, on a timely basis, or at all. As of the date the accompanying condensed consolidated financial statements were issued, management concluded that the Company did not have sufficient capital on hand to support its current cost structure for twelve months after the date the accompanying condensed consolidated financial statements were issued. The Company expects to continue to incur significant losses and net operating cash outflows from operations for the foreseeable future. The Company expects to continue to require additional capital to fund operations and meet its obligations as they become due. The Company believes these uncertainties raise substantial doubt about the Company’s ability to continue as a going concern. If the Company is unable to raise additional capital, on acceptable terms, or at all, the Company may have to significantly delay, scale back or ultimately discontinue the development or commercialization of its product and/or consider a sale or other strategic transactions. The accompanying condensed consolidated financial statements have been prepared on the basis that the Company will continue to operate as a going-concern, which contemplates the Company will be able to realize assets and settle liabilities and commitments in the normal course of business for the foreseeable future. The accompanying condensed consolidated financial statements do not include any adjustments that may result from the outcome of these uncertainties. Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of the Company and its 100% owned, direct and indirect subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). All intercompany transactions and balances have been eliminated in the preparation of the condensed consolidated financial statements. These statements reflect all adjustments, consisting of normal recurring adjustments, which, in the opinion of management, are necessary for fair presentation of the information contained therein. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. These interim results are not necessarily indicative of results for the full year. Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations. Foreign Currency The Company follows the provisions of ASC 830, Foreign Currency Matters. The Company’s foreign subsidiaries use the local currency of their respective countries as their functional currency. The assets and liabilities of foreign operations are translated at the exchange rates in effect at the balance sheet date. The operating results of foreign operations are translated at weighted average exchange rates. The related translation gains or losses are reported as a separate component of shareholders’ (deficit) equity in accumulated other comprehensive loss. Gains and losses from foreign currency transactions, which were insignificant for the three and nine months ended September 30, 2022 and 2021, are included as other income (expense) in the condensed consolidated statements of operations and comprehensive loss. Recently Adopted Accounting Pronouncements On January 1, 2021, the Company adopted ASU 2016-02, Leases (“Topic 842”), using the transition method introduced by ASU 2018-11, which does not require revisions to comparative periods. The adoption of the new standard resulted in the recording of lease assets and lease liabilities of $3,662 and $4,465, respectively, as of January 1, 2021. The difference between the lease assets and lease liabilities primarily relates to deferred rent recorded in accordance with the previous leasing guidance. The new standard did not materially impact the Company’s condensed consolidated statements of operations and comprehensive loss or statements of cash flows. On January 1, 2021, the Company adopted ASU No. 2016-13, Financial Instruments-Credit Losses (“Topic 326”), and the subsequent amendments. The standard sets forth an expected credit loss model which requires the measurement of expected credit losses for financial instruments based on historical experience, current conditions and reasonable and supportable forecasts. This replaces the existing incurred loss model and is applicable to the measurement of credit losses on financial assets measured at amortized cost, and certain off-balance sheet credit exposures. The adoption of this standard did not have a material impact on the Company’s condensed consolidated financial statements. Recent Accounting Pronouncements As of September 30, 2022, the Company implemented all applicable new accounting standard updates (“ASU”) issued by the Financial Accounting Standards Board (“FASB”) that were in effect. There were no new standards or updates issued during the nine months ended September 30, 2022 that would have a material impact on the Company’s condensed consolidated financial statements.

Eos Energy Enterprises, Inc. (the “Company” or "Eos") designs, develops, manufactures, and sells innovative energy storage solutions for utility-scale microgrid, and commercial & industrial (“C&I”) applications. Eos has developed a broad range of intellectual property with multiple patents ranging from the unique battery chemistry, mechanical product design, energy block configuration and software operating system (“Battery Management System” or “BMS”). The BMS software uses proprietary, Eos-developed algorithms and includes ambient and battery temperature sensors, as well as voltage and electrical current sensors for the electrical strings and the system. Eos focuses on developing and selling safe, reliable, long-lasting and low-cost turn-key alternating current (“AC”) integrated systems using Eos’ direct current (“DC”) battery energy storage system. The Company has a manufacturing facility in Turtle Creek, Pennsylvania to produce DC energy blocks with an integrated BMS. The Company’s primary applications focus on integrating battery storage solutions with: (1) renewable energy systems that are connected to the utility power grid; (2) renewable energy systems that are not connected to the utility power grid; (3) energy systems utilized to relieve congestion; and (4) storage systems to assist C&I customers in reducing their peak energy usage or participating in the utilities ancillary and demand response markets. The Company’s major market is North America with opportunistic growth opportunities in Europe, Oceania, Africa, and Asia.

Under U.S. GAAP, the Company is required to perform a two-step analysis of its ability to continue as a going concern: It must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued or available to be issued (Step 1). If the Company concludes that substantial doubt is raised, it is also required to consider whether the Company’s plans alleviate the substantial doubt (Step 2).

The Company continues to scale its operations, including deploying additional capital for capacity expansion to meet current customer demand. To date, the Company has incurred significant recurring losses and net operating cash outflows from operations. Operating expenses consist primarily of costs related to the Company’s research and development, sales activities, and recurring general and administrative expenses. Management and the Company’s Board of Directors expect the Company will eventually reach a scale of profitability through the sale of battery energy storage systems and other complementary products and services, and therefore, the Company believes the current stage of the Company’s lifecycle justifies continued intensive investment in the development and launch of products. Accordingly, the Company expects to continue to incur significant losses and net operating cash outflows from operations for the foreseeable future and to continue to require additional capital to fund the Company’s operations and obligations as they become due, including funding that is necessary to continue to scale up the Company’s operations to allow for the delivery of backlog, to secure additional order opportunities for its battery storage systems, and to continue to invest in research and development.

As of September 30, 2022, the Company had total assets of $138,481, including cash, cash equivalents and restricted cash of $51,047 (refer to Note 4, Cash, Cash Equivalents and Restricted Cash), total liabilities of $226,820, which includes the total amounts owed on the Company’s outstanding convertible notes payable of $78,743 and long-term debt of $84,775 (refer to Note 12, Borrowings) and a total accumulated deficit of $589,727, which is primarily attributable to the significant recurring losses the Company has accumulated since inception. The Company used cash in operating activities of $159,129 for the nine months ended September 30, 2022.

During the third quarter of 2022, the Company obtained the following additional financing: (a) the Company borrowed $94,681 under a Senior Secured Term Loan agreement (the “Term Loan”) to fund the Company’s manufacturing capacity, repay an existing outstanding note, and for general corporate purposes; (b) the Company borrowed an additional $4,216 under the equipment financing facility with Trinity Capital, Inc.; and (c) the Company entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”) with respect to an at-the-market offering program. Under the at-the-market-offering program, the Company may offer and sell, from time to time at its sole discretion, shares of its common stock, having an aggregate offering price up to $100,000 through Cowen as sales agent and/or principal. The Company will pay Cowen a commission equal to 3.0% of the gross sales proceeds of any shares of the Company’s common stock sold through Cowen. In the third quarter, under this at-the-market program, the Company issued and sold a total of 12,067,575 shares and raised $30,040 ($29,139 net of commissions) at an average selling price of $2.49 per share.

The Term Loan agreement contains customary affirmative and negative covenants, which limit the Company’s and its subsidiaries’ ability to incur indebtedness, make restricted payments, including cash dividends on its common stock, make certain investments, loans and advances, enter into mergers and acquisitions, sell, assign, transfer or otherwise dispose of its assets, enter into transactions with its affiliates and engage in sale and leaseback transactions, among other restrictions (refer to Note 12, Borrowings). The Company was in compliance with all Term Loan covenants as of September 30, 2022.

In the second quarter of 2022, the Company entered into a $200,000 common stock Standby Equity Purchase Agreement (“SEPA”) with YA II PN, Ltd. an affiliate of Yorkville Advisors, which was subsequently amended on June 13, 2022. The SEPA gives the Company the right, but not the obligation, to sell up to $200,000 of common equity to Yorkville at times of the Company’s choosing during the two-year term of the agreement. The SEPA provides for shares to be issued to Yorkville at a discounted price of 97.0% of the 3-day volume-weighted average price following notification to Yorkville that the Company seeks to draw upon the facility (refer to Note 11, Related Party Transactions and Note 12, Borrowings). Through the date of this filing, funds raised under the SEPA were $12,500; the Company did not utilize the SEPA in the third quarter.

As previously reported, the Company has moved through Part I of the application under the U.S. Department of Energy’s Loan Guarantee Solicitation for Applications for Renewable Energy Projects and Efficient Energy Projects (the “DOE Loan Program”) and submitted an application under Part II of the loan program in May 2022. In September 2022, the Company was invited to the due diligence stage of the DOE Loan Program. During this stage, the Company and the DOE will work to negotiate a term sheet setting out the principal terms and conditions of the loan. This work provides the DOE the foundation to advance the loan towards a conditional commitment. However, the DOE invitation to the due diligence stage is not an assurance that the DOE will offer a conditional commitment, or that the Company will secure a loan under the DOE Loan Program. The Company is seeking additional capital through securities offerings, other financing arrangements and grants to raise additional funding to support its operations.

There can be no assurance that the Company will be able to utilize the full value under the Sales Agreement with Cowen, utilize the SEPA to its full $200,000 capacity, successfully complete the DOE Loan Program, or otherwise be able to obtain new funding from other sources on terms acceptable to the Company, on a timely basis, or at all.

As of the date the accompanying condensed consolidated financial statements were issued, management concluded that the Company did not have sufficient capital on hand to support its current cost structure for twelve months after the date the accompanying condensed consolidated financial statements were issued. The Company expects to continue to incur significant losses and net operating cash outflows from operations for the foreseeable future. The Company expects to continue to require additional capital to fund operations and meet its obligations as they become due. The Company believes these uncertainties raise substantial doubt about the Company’s ability to continue as a going concern. If the Company is unable to raise additional capital, on acceptable terms, or at all, the Company may have to significantly delay, scale back or ultimately discontinue the development or commercialization of its product and/or consider a sale or other strategic transactions.

The accompanying condensed consolidated financial statements have been prepared on the basis that the Company will continue to operate as a going-concern, which contemplates the Company will be able to realize assets and settle liabilities and commitments in the normal course of business for the foreseeable future. The accompanying condensed consolidated financial statements do not include any adjustments that may result from the outcome of these uncertainties.

The accompanying condensed consolidated financial statements include the accounts of the Company and its 100% owned, direct and indirect subsidiaries and have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). All intercompany transactions and balances have been eliminated in the preparation of the condensed consolidated financial statements. These statements reflect all adjustments, consisting of normal recurring adjustments, which, in the opinion of management, are necessary for fair presentation of the information contained therein. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”). These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements, and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. These interim results are not necessarily indicative of results for the full year.

The Company follows the provisions of ASC 830, Foreign Currency Matters. The Company’s foreign subsidiaries use the local currency of their respective countries as their functional currency. The assets and liabilities of foreign operations are translated at the exchange rates in effect at the balance sheet date. The operating results of foreign operations are translated at weighted average exchange rates. The related translation gains or losses are reported as a separate component of shareholders’ (deficit) equity in accumulated other comprehensive loss. Gains and losses from foreign currency transactions, which were insignificant for the three and nine months ended September 30, 2022 and 2021, are included as other income (expense) in the condensed consolidated statements of operations and comprehensive loss.

On January 1, 2021, the Company adopted ASU 2016-02, Leases (“Topic 842”), using the transition method introduced by ASU 2018-11, which does not require revisions to comparative periods. The adoption of the new standard resulted in the recording of lease assets and lease liabilities of $3,662 and $4,465, respectively, as of January 1, 2021. The difference between the lease assets and lease liabilities primarily relates to deferred rent recorded in accordance with the previous leasing guidance. The new standard did not materially impact the Company’s condensed consolidated statements of operations and comprehensive loss or statements of cash flows.

On January 1, 2021, the Company adopted ASU No. 2016-13, Financial Instruments-Credit Losses (“Topic 326”), and the subsequent amendments. The standard sets forth an expected credit loss model which requires the measurement of expected credit losses for financial instruments based on historical experience, current conditions and reasonable and supportable forecasts. This replaces the existing incurred loss model and is applicable to the measurement of credit losses on financial assets measured at amortized cost, and certain off-balance sheet credit exposures. The adoption of this standard did not have a material impact on the Company’s condensed consolidated financial statements.

As of September 30, 2022, the Company implemented all applicable new accounting standard updates (“ASU”) issued by the Financial Accounting Standards Board (“FASB”) that were in effect. There were no new standards or updates issued during the nine months ended September 30, 2022 that would have a material impact on the Company’s condensed consolidated financial statements.