TECOGEN INC.

Note 1. Description of Business and Basis of Presentation

Description of Business

Tecogen Inc., a Delaware corporation (together with its subsidiaries "we", "our", "us", "Tecogen," or "Company"), was incorporated on September 15, 2000. We produce commercial and industrial, natural-gas-fueled engine-driven, combined heat and power (CHP) products that reduce energy costs, decrease greenhouse gas emissions and alleviate congestion on the national power grid. Our products supply electric power or mechanical power for cooling, while heat from the engine is recovered and purposefully used at a customer facility. The majority of our customers are located in regions with the highest utility rates, typically California, the Midwest and the Northeast.

Our operations are comprised ofthree business segments. Our Products segment designs, manufactures and sells industrial and commercial cogeneration systems. Our Services segment provides operation and maintenance services to customers for our products. Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements.

On April 30, 2025, we announced that shares our shares of common stock had been approved for listing on the NYSE American LLC ("NYSE American"), stock exchange. On May 6, 2025, our common stock began trading on the NYSE American under our current symbol "TGEN."

On July 21, 2025, we closed on the sale of an aggregate of 3,985,000 shares of common stock, $0.001 par value per share ("Common Stock"), including an additional 485,000 shares of common stock to cover over-allotments, at a price to the public of $5.00 per share (before deduction of underwriting discounts and commissions), in a firm commitment underwritten public offering pursuant to an underwriting agreement, dated July 18, 2025 ("Underwriting Agreement"), between the Company and Roth Capital Partners, LLC ("Roth") as sole underwriter and manager for the offering ("Offering"). The net proceeds from the Offering, after deducting underwriting discounts and commissions and offering expenses were approximately $18,105,100. The net Offering proceeds were as follows:

Basis of Presentation

The financial statements have been prepared in accordance with accounting standards set by the Financial Accounting Standards Board, or FASB. The FASB sets United States' ("U.S.") generally accepted accounting principles, or U.S. GAAP, to ensure financial condition, results of operations, and cash flows are consistently reported. References to U.S. GAAP issued by the FASB in these footnotes are to the FASB Accounting Standards Codification, or ASC. We adopted the presentation requirements for noncontrolling interests required by ASC 810 Consolidation. Under ASC 810, earnings or losses attributed to the noncontrolling interests are reported as part of the consolidated earnings and not a separate component of income or expense.

The accompanying condensed consolidated financial statements include our accounts and the accounts of the entities in which we have a controlling financial interest. Those entities include our wholly-owned subsidiary, American DG Energy Inc. ("ADGE"), Tecogen CHP Solutions, Inc., and a joint venture, American DG New York, LLC, or ADGNY, in which ADGE holds a 51.0% interest. As the controlling partner, all major decisions in respect of ADGNY are made by ADGE in accordance with the joint venture agreement. The interests in the individual underlying energy system projects in ADGNY vary between ADGE and its joint venture partner. The noncontrolling interest and distributions are determined based on economic ownership. The economic ownership is calculated by the amount invested by us and the noncontrolling partner in each site. Each quarter, we calculate a year-to-date profit or loss for each site that is part of ADGNY and the noncontrolling interest percent of economic ownership in each site is applied to determine the noncontrolling interest share in the profit or loss. The same methodology is used to determine quarterly distributions of available cash to the noncontrolling interest partner. On our balance sheet, noncontrolling interest represents the joint venture partner’s investment in ADGNY, plus its share of after-tax profits less any cash distributions. ADGE owned a controlling 51.0% legal and economic interest in ADGNY as of September 30, 2025 and December 31, 2024. Operating results for the nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. All intercompany transactions have been eliminated in consolidation.

The condensed consolidated balance sheet at December 31, 2024 has been derived from the audited consolidated financial statements at that date included in our Annual Report on Form 10-K for the year ended December 31, 2024, but does not include all of the information and footnotes required by U.S. GAAP for complete financial statements.

For further information, refer to the consolidated financial statements and footnotes thereto included in Tecogen's Annual Report on Form 10-K for the year ended December 31, 2024.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Inventory

Raw materials, work in process, and finished goods inventories are stated at the lower of cost, as determined by the average cost method, or net realizable value. We periodically review inventory quantities on hand for excess and/or obsolete inventory based primarily on historical usage, as well as based on estimated forecast of product demand. Any reserves that result from this review are charged to cost of sales.

Income Taxes

The provisions for income taxes in the accompanying unaudited consolidated statements of operations differ from that which would be expected by applying the federal statutory tax rate primarily due to losses for which no benefit is recognized.

Business Combinations

In accordance with applicable accounting standards, we estimate the fair value of assets acquired and liabilities assumed as of the acquisition date of each business combination. Any excess purchase price over the fair value of the net tangible and intangible assets acquired is allocated to goodwill. We may make certain estimates and assumptions when determining the fair values of assets acquired and liabilities assumed, including intangible assets. Critical estimates in valuing certain intangible assets include but are not limited to future expected cash flows from energy production sites or customer maintenance contracts, estimated operating costs, as well as discount rates. At the acquisition date, we will also record acquisition related liabilities, if applicable, for any contingent consideration or deferred payments to the seller and pre-acquisition deferred maintenance contingencies identified at service contract acquisition. Contingent consideration and pre-acquisition deferred maintenance contingencies are recorded at fair value on the acquisition date based on our expectation of achieving the contractually defined revenue targets and actual and projected future costs. The fair value of the contingent consideration and pre-acquisition deferred maintenance liabilities are remeasured each reporting period after the acquisition date and any changes in the estimated fair value are reflected as gains or losses in cost of goods sold or general and administrative expense in the condensed consolidated statements of operations. Contingent consideration liabilities and deferred payments to sellers are recorded as current liabilities and other long-term liabilities in the consolidated balance sheets based on the expected timing of settlement.

Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Any changes to provisional amounts identified during the measurement period are recognized in the reporting period in which the adjustment amounts are determined. Transaction costs associated with business combinations are expensed as incurred.

Segment Information

Our operations are comprised ofthree business segments. Our Products segment designs, manufactures and sells industrial and commercial cogeneration systems as described above. Our Services segment installs and maintains our cogeneration systems. Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements. Segment profit is based on operating income after the elimination of intercompany transactions. Segment profit is a measure of operating performance of our reportable segments and may not be comparable to similar measures reported by other companies. Segment profit is a performance metric utilized by our Chief Executive Officer, who is our Chief Operating Decision Maker, to allocate resources to and assess performance of our segments. See "Note 13.

Segments " of the Notes to Condensed Consolidated Financial Statements, for a reconciliation of segment profit to income from operations.

Recently Issued Accounting Standards

Income Taxes (Topic 740) - Improvements to Income Tax Disclosures. In December 2023, the Financial Accounting Standards Board issued ASU 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures. ASU 2023-09 provides more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. The amendments in this update are effective for annual periods beginning after December 15, 2024. Early adoption is permitted. The adoption of Topic 740 did not have a material effect on our consolidated financial statements, other than with respect to expanded disclosure.

Compensation - Stock Compensation (Topic 718) -In March 2024, the Financial Accounting Standards Board issued ASU 2024-01, Compensation - Stock Compensation (Topic 718). ASU 2024-01 addresses generally accepted accounting principles relating to profits interest awards and similar awards provided to employees or non-employees to align compensation with an entity's operating performance and provide the holders with the opportunity to participate in future profits and/or equity appreciation of the entity. The amendments in this Update are effective for annual periods beginning after December 15, 2024, and interim periods within those annual periods for public entities. For all other entities, the amendments are effective for annual periods beginning after December 15, 2025, and interim periods within those annual periods. Early adoption is permitted for both interim and annual financial statements that have not yet been issued or made available for issuance We do not issue profits interest awards, and therefore, the adoption of ASU 2024-01 024-01 did not have a material effect on our financial position or results of operation.

Codification Improvements – Amendments to Remove References to the Concepts Statements. In March 2024, the Financial Accounting Standards Board issued ASU 2024-02, Codification Improvements – Amendments to Remove References to the Concepts Statements. ASU 2024-02 contains amendments to the Codification that remove references to various FASB Concept Statements, affecting a variety of Topics in the Codification and applies to all reporting entities. The amendments in this update are effective for public entities for fiscal years beginning after December 15, 2024. Early application of the amendments in this update are permitted for any fiscal year or interim period for which financial statements have not yet been issued or made available for issuance. If adopted in an interim period, the amendment must be adopted as of the beginning of the fiscal year that includes the interim period. An entity should apply the amendments prospectively to all new transactions recognized on or after the date that the entity first applies the amendments, or retrospectively to the beginning of the earliest comparative period presented in which the amendments were first applied, by adjusting the opening balance of retained earnings, or other appropriate components of equity or net assets, as of the beginning of the earliest comparative period presented. The adoption of ASU 2024-02 did not have a material effect on our financial position or results of operation.

Income Statement – Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40). In November 2024, the Financial Accounting Standards Board issued ASU 2024-03, Income Statement - Reporting Comprehensive Income – Expense Disaggregation Disclosures (Subtopic 220-40). This update is intended to improve disclosures about public entity’s expenses and will require more detailed information about types of expenses including inventory purchases, employee compensation, depreciation, amortization and depletion in commonly presented captions such as cost of sales, SG&A and research and development. In addition, an entity will be required to include certain amounts that are already disclosed under U.S. GAAP in the same disclosure as the other disaggregation requirements; disclose a qualitative description of the amounts remaining in expense captions not separately disaggregated quantitatively; and, disclose the amount of selling expense and, in annual reporting periods, the entity’s definition of selling expenses. The amendments are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The amendments should be applied prospectively to the financial statements after the effective date and retrospectively to any and all prior periods presented in the financial statements. ASU 2024-03 will apply to Tecogen after December 15, 2026, adoption of which will not have a material effect on our financial position or results of operation, but will require additional disclosure.

Financial Instruments - Credit Losses Topic (326). In July 2025, the Financial Accounting Standards Board issued ASU 2025-05, Financial Instruments-Credit Losses (Topic 326) - Measurement of Credit Losses for Accounts Receivable and Contract Assets. This update is intended to address challenges encountered when applying the guidance of Topic 326, Financial Instruments-Credit Losses to accounts receivable and current contract assets arising from transactions accounted for under Topic 606, Revenue from Contracts with Customers. The amendments in this update provide all entities with a practical expedient and entities other than public entities with an accounting policy election when estimating expected credit losses for current accounts receivable and current contract assets arising from transactions accounted for under Topic 606. Under Topic 326, in developing reasonable and supportable forecasts of expected credit losses, an entity is required to consider historical credit loss experience of financial assets with similar risks characteristics which generally provides a basis for an entity's assessment of credit losses, but also requires the entity to consider adjustments to that information to reflect the extent to which the entity expects current conditions and reasonable and supportable forecasts to differ from the conditions that existed for the period over which historical information was evaluated. The update allows entities to elect a practical expedient that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The amendments are effective for annual reporting periods beginning after December 15, 2025, and interim periods within those annual reporting periods. Early adoption is permitted in permitted in both interim and annual reporting periods in which financial statements have not yet been issued or made available for issuance. The amendments should be applied prospectively. ASU 2025-05 will apply to Tecogen after December 15, 2025. We are currently evaluating the impact on our consolidated financial statements and related disclosures.

Note 2. Revenue

Revenue is recognized when performance obligations under the terms of a contract with a customer are satisfied; generally, this occurs with the transfer of control of our products, services, and energy production. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring goods or providing services or energy to customers.

Shipping and handling fees billed to customers in sales transactions are recorded in revenue and shipping and handling costs incurred are recorded in cost of sales. We have elected to exclude from revenue any value-added sales and other taxes which we collect concurrent with revenue-producing activities. These accounting policy elections are consistent with the manner in which historically we have recorded shipping and handling fees and value-added taxes. Incremental costs incurred by us to obtain a contract with a customer are negligible, if any, and are expensed ratably in proportion to the related revenue recognized.

Disaggregated Revenue

In general, our business segmentation is aligned according to the nature and economic characteristics of our products and customer relationships and provides meaningful disaggregation of each business segment's results of operations. See "Note 13. Segments" of the Notes to Condensed Consolidated Financial Statements.

The following table further disaggregates our revenue by major source and by segment for the three and nine months ended September 30, 2025 and 2024.

Products Segment

Products. Our Products revenues include cogeneration systems that supply electricity and hot water, chillers that provide air-conditioning and hot water and engineered accessories, which consist of ancillary products and parts necessary to install a cogeneration unit including integration into the customers’ existing electrical and mechanical systems. We refer to the package of engineered accessories and engineering and design services necessary for the customers' installation of a cogeneration unit as light installation services.

We transfer control and generally recognize a sale when we ship a product from our manufacturing facility at which point title has transferred and the customer takes ownership of the product. Payment terms on product sales are generally thirty (30) days.

We recognize revenue in certain circumstances before delivery to the customer has occurred (commonly referred to as bill and hold transactions). We recognize revenue related to such transactions once, among other things, the customer has made a written fixed commitment to purchase the product(s) under normal billing and credit terms, the customer has requested the product(s) be held for future delivery as scheduled and designated by them, risk of ownership has been assumed by the customer, and the product(s) are tagged as sold and segregated for storage awaiting further direction from the customer. Due to the infrequent nature and duration of bill and hold arrangements, the value associated with custodial storage services is deemed immaterial in the context of the contract and in total, and, accordingly, none of the transaction price is allocated to such service.

Depending on the product and terms of the arrangement, we may defer the recognition of a portion of the transaction price received because we have to satisfy a future obligation (e.g., product start-up service). Amounts allocated to product start-up services are recognized as revenue when the start-up service has been completed. We use an observable selling price to determine standalone selling prices where available and either a combination of an adjusted market assessment approach, an expected cost plus a margin approach, and/or a residual approach to determine the standalone selling prices for separate performance obligations as a basis for allocating contract consideration when an observable selling price is not available. Amounts received but not recognized pending completion of performance are recognized as contract liabilities and are recorded as deferred revenue along with deposits by customers.

Services Segment

Maintenance services are provided under either long-term maintenance contracts or time and material maintenance contracts. Revenue under time and material maintenance contracts is recognized when the maintenance service is completed. Revenue under long-term maintenance contracts is recognized either ratably over the term of the contract where the contract price is fixed or when the periodic maintenance activities are completed and the invoiced cost to the customer is based on run hours or kilowatts produced in a given period. We use an output method to measure progress towards completion of our performance obligation which results in the recognition of revenue on the basis of a direct measurement of the value to the customer of the services transferred to date relative to the remaining services promised under the contract. We use the practical expedient at ASC 606-10-55-18 of recognizing revenue in an amount equal to the amount we have the right to invoice the customer under the contract.

Our initial acquisition of the Aegis Energy Services, LLC ("Aegis"), maintenance contracts and related business closed on March 15, 2023. We have included the financial results of the Aegis maintenance agreements in our condensed consolidated financial statements from April 1, 2023, from February 1, 2024 and from May 1, 2024, the closing or acquisition dates for the acquisitions in our revenue from the Services segment. See "Note 7. Aegis Contract and Related Asset Acquisitions" of the Notes to Condensed Consolidated Statements for a further discussion of the Aegis acquisition. Payment terms for maintenance services are generally thirty (30) days.

Energy Production Segment

Revenue from energy contracts is recognized when electricity, heat, hot and/or chilled water is produced by our owned on-site cogeneration systems. Each month we bill the customer and recognize revenue for the various forms of energy delivered, based on meter readings which capture the quantity of the various forms of energy delivered in a given month under a contractually defined formula which takes into account the current month's cost of energy from the local power utility.

As the various forms of energy delivered by us under energy production contracts are simultaneously delivered and consumed by the customer, our performance obligation under these contracts is considered to be satisfied over time. We use an output method to measure progress towards completion of our performance obligation which results in the recognition of revenue on the basis of a direct measurement of the value to the customer of the services transferred to date relative to the remaining services promised under the contract. We use the practical expedient at ASC 606-10-55-18 of recognizing revenue in an amount equal to that amount to which we have the right to invoice the customer under the contract. Payment terms on invoices under these contracts are generally thirty (30) days.

Contract Balances

The timing of revenue recognition, billings and cash collections result in billed accounts receivable, unbilled revenue (contract assets) and deferred revenue, consisting of customer deposits and billings in excess of revenue recognized (contract liabilities) on the condensed consolidated balance sheets.

We did not recognize any revenue during the nine months ended September 30, 2025, that was included in unbilled revenue as of September 30, 2025.

Revenue recognized during the nine months ended September 30, 2025, that was included in deferred revenue at December 31, 2024 was approximately $5,452,648.

Remaining Performance Obligations

Remaining performance obligations related to ASC 606 represent the aggregate transaction price allocated to performance obligations with an original contract term of greater than one year, excluding certain maintenance contracts and all energy production contracts where a direct measurement of the value to the customer is used as a method of measuring progress towards completion of our performance obligation. Exclusion of these remaining performance obligations is due in part to the inability to quantify values based on unknown future levels of delivery and in some cases rates used to invoice customers. Remaining performance obligations therefore consist of unsatisfied or partially satisfied performance obligations related to fixed price maintenance contracts and installation contracts.

As of September 30, 2025, the aggregate amount of the transaction price allocated to remaining performance obligations was approximately $4,882,806. We expect to recognize revenue of approximately 79.4% of the remaining performance obligations over the next 24 months,75.6% recognized in the first 12 months and 3.8% recognized over the subsequent 12 months and the balance thereafter.

Note 3. Income (Loss) Per Common Share

Basic and diluted loss per share for the three and nine months ended September 30, 2025 and 2024, respectively, were as follows:

Inventories at September 30, 2025 and December 31, 2024 consisted of the following:

Note 5. Property, Plant and Equipment, net

Property, plant and equipment at September 30, 2025 and December 31, 2024 consisted of the following:

• Lesser of estimated useful life of asset or lease term

Depreciation and amortization expense on property and equipment for the three and nine months ended September 30, 2025 and 2024 was $104,405 and $300,371 and $101,780 and $307,491, respectively.

Note 6. Intangible Assets and Liabilities Other Than Goodwill

As of September 30, 2025 and December 31, 2024 we had the following amounts related to intangible assets and liabilities other than goodwill:

The aggregate amortization expense related to non-contract related intangible assets were $46,686 and $132,670 and $46,127 and $149,476 for the three and nine months ended September 30, 2025 and 2024, respectively. The net aggregate expense (credit) related to the amortization of the contract related intangible assets and liabilities for the three and nine months ended September 30, 2025 and 2024 were $22,069 and $54,517 and $6,015 and $342, respectively.

Contract Related Intangibles

The favorable contract asset and unfavorable contract liability in the foregoing table represent the fair value of ADGE's customer contracts (both positive for favorable contracts and negative for unfavorable contracts) which were acquired by us on May 18, 2017. The customer contract asset includes the maintenance services contracts acquired by us on April 1, 2023 as part of the Aegis acquisition and pursuant to the February 2024 Amendment and the May 2024 Amendment. See" Note 7. Aegis Contract and Related Asset Acquisitions."

Amortization of intangibles including contract related amounts is calculated using the straight-line method over the remaining useful life or contract term, which range from approximatelyone year toeleven years, and is charged against either administrative expenses or cost of sales in the accompanying condensed consolidated statement of operations. Aggregate future amortization over the next five years is estimated to be as follows as of September 30, 2025:

On March 15, 2023, we entered into an agreement ("Assumption Agreement") with Aegis Energy Services, LLC (“Aegis”), pursuant to which Aegis agreed to assign to us and we agreed to assume certain Aegis maintenance agreements, we agreed to purchase certain assets from Aegis, and related matters (“Acquisition”). On April 1, 2023, the Acquisition closed. Under the Assumption Agreement, we agreed to acquire from Aegis and assume Aegis’ rights and obligations arising on or after April 1, 2023, under maintenance agreements pursuant to which Aegis provided maintenance services to third parties for approximately 200 cogeneration systems and we agreed to acquire from Aegis certain vehicles and inventory used by Aegis in connection with the performance of its maintenance services. At closing, we acquired eight (8) Aegis vehicles for consideration consisting of $170,000 in cash. Also, we issued credits against outstanding accounts receivable due from Aegis in the amount of $300,000 for the acquisition of inventory that Aegis used to provide maintenance services. At closing, we hired eight (8) Aegis employees who, following the closing, have agreed to continue to provide maintenance services relating to the cogeneration systems covered by the maintenance agreements assumed pursuant to the Assumption Agreement. Following the closing and for a period of up to seven (7) years, we agreed to pay Aegis a percentage of the revenue collected for maintenance services provided pursuant to the maintenance agreements acquired from Aegis. Further, prior to December 31, 2023, we had the right to acquire and assume additional Aegis’ maintenance agreements for cogeneration systems on substantially similar terms and conditions. The Assumption Agreement contained certain indemnification provisions and agreements on the part of Aegis and for each party to cooperate with each other and provide certain transitional assistance. We acquired the Aegis maintenance agreements to expand our Service portfolio and to benefit from the long-term contract revenue stream generated by these agreements.

On February 1, 2024, Tecogen and Aegis amended the Assumption Agreement to add eighteen (18) additional maintenance contracts assumed by us ("February 2024 Amendment") which includes an undertaking by Aegis to use commercially reasonable efforts to support and assist our execution of maintenance service agreements for an additional thirty-six (36) cogeneration units sold to customers by Aegis.

On May 1, 2024, Tecogen and Aegis amended the Assumption Agreement to add thirty-one (31) additional maintenance contracts assumed by us ("May 2024 Amendment") which includes an undertaking by Aegis to use commercially reasonable efforts to support and assist our execution of maintenance service agreements for an additional forty-eight (48) cogeneration units sold to customers by Aegis.

No additional maintenance service agreements contemplated in the February 2024 Amendment or the May 2024 Amendment have been acquired as of September 30, 2025.

We have determined that the assignment and assumption of the Aegis maintenance agreements, in combination with the related asset acquisition and the retention of the former Aegis employees, constitutes a business and should be accounted for as a business combination under the acquisition method. As of the Acquisition date, we recognized, separately from goodwill, the identifiable assets acquired and the liabilities assumed, at fair value. We have applied an interpretation of the guidance in ASC 805, Business Combinations, that allows an entity to combine multiple acquisitions as one single transaction due to the April 1, 2023, February 1, 2024, and May 1, 2024, acquisitions being executed in contemplation of one another to achieve the same commercial objective for the Company. As a result, we have adjusted the initial accounting for the April 1, 2023 acquisition for the value of net assets acquired from the February 1, 2024 and May 1, 2024 acquisitions.

We have included the financial results of the Aegis maintenance agreements in our condensed consolidated financial statements from April 1, 2023, from February 1, 2024, and from May 1, 2024, the closing or acquisition dates for the acquisitions.

The following table summarizes the consideration paid for the Aegis acquisition and the fair value of assets acquired and contract-related liabilities assumed as of the acquisition date:

Initial Acquisition - April 1, 2023

The amounts initially recognized for inventory, identifiable intangible assets, contingent consideration and deferred maintenance reserves were provisional pending completion of the necessary valuations and analysis. ASC 805 establishes a measurement period to provide companies with a reasonable amount of time to obtain the information necessary to identify and measure various items in a business combination and cannot extend beyond one year from the acquisition date. As of December 31, 2023, we completed our analysis and valuation.

As of December 31, 2024, we recorded no remeasurement adjustments to the fair value of the contingent consideration and deferred maintenance reserves given the probability of achieving the revenue estimates and the actual and expected maintenance costs were consistent with our initial valuation.

February 2024 Amendment

The amounts initially recognized for identifiable intangible assets and contingent consideration were provisional, pending completion of the necessary valuations and analysis. ASC 805 establishes a measurement period to provide companies with a reasonable amount of time to obtain the information necessary to identify and measure various items in a business combination and cannot extend beyond one year from the acquisition date. As of December 31, 2024, we completed our analysis and valuation for the February 2024 Amendment.

May 2024 Amendment

The amounts initially recognized for identifiable intangible assets and contingent consideration were provisional pending completion of the necessary valuations and analysis. ASC 805 establishes a measurement period to provide companies with a reasonable amount of time to obtain the information necessary to identify and measure various items in a business combination and cannot extend beyond one year from the acquisition date. As of December 31, 2024, we completed our analysis and valuation for the May 2024 Amendment.

Acquisition Valuation

The fair value of the identifiable intangible asset was estimated using the income approach. The excess cash flow was discounted to present value using an appropriate rate of return to estimate the market value of the customer identifiable intangible asset and the risks associated with the future revenue forecasts due to potential changes in customer energy requirements or changes in the economic viability of these CHP sites which depend on the spread between natural gas fuel and electricity prices, all of which are not within our control. Key assumptions to value the customer identifiable intangible asset included the discount rate of 15%, profitability assumptions, revenue assumptions, and anticipated existing contract run out were the material assumptions utilized in the discounted cash flow model used to estimate fair value. The discount rate reflects an estimate of our weighted-average cost of capital.

Following the closing and for a period of up to seven (7) years, we agreed to pay Aegis contingent consideration equal to a percentage of the revenue collected for maintenance services provided pursuant to the maintenance agreements acquired from Aegis. On the date of acquisition, the fair value of the contingent consideration and the deferred maintenance reserve were calculated under the income approach using a weighted average cost of capital of 15%, discounting the future cash flows to present value, and are subsequently remeasured to fair value at each reporting date until the fair value contingencies are resolved. Fair value adjustments which may be determined at subsequent reporting dates will be recorded in our condensed consolidated statements of operations and will not impact the goodwill balance after the measurement period.

The contingent consideration is payable within forty-five (45) days following the end of each calendar quarter through the earlier of the expiration or termination of the relevant maintenance agreements, or the seventh (7th) anniversary of the acquisition date. The consideration is equal to the product of the revenues collected in a calendar quarter multiplied by an applicable percentage. The agreement stipulates quarterly aggregate revenue targets and an applicable percentage, and provides for a higher applicable percentage if revenues exceed the target revenues. The applicable percentage ranges from 5% to 10% over the agreement term. The deferred maintenance reserve represents costs, which are expected to be incurred over athree-year period from the date of acquisition to repair customer equipment which had not been sufficiently maintained prior to our acquisition of the maintenance service agreements.

The purchase price of the acquisition was allocated to the tangible and intangible assets acquired and liabilities assumed and recognized at their fair value based on widely accepted valuation techniques in accordance with ASC 820, "Fair Value Measurement," as of the acquisition date. The process for estimating fair value requires the use of significant assumptions and estimates of future cash flows and developing appropriate discount rates. The excess of the purchase price over fair value of the net identified assets acquired and liabilities assumed was recorded as goodwill. Goodwill is primarily attributable to the going concern element of the Aegis business, including its assembled workforce and the long-term nature of the customer maintenance agreements, as well as anticipated cost synergies due primarily to the elimination of administrative overhead. Goodwill resulting from the Aegis acquisition is not expected to be deductible for income tax purposes.

Acquisition-related costs which consisted of recurring internal resources were de minimis and such costs were expensed as incurred (ASC 805-50-30-1). The following table summarizes the contract-related liabilities assumed as of September 30, 2025 and December 31, 2024:

Revenues and gross profit from the Aegis maintenance contracts were $467,132 and $273,325 and $1,660,159 and $1,007,390, respectively, for the three and nine months ended September 30, 2025. Revenue and gross profit for the three and nine months ended September 30, 2024 were $537,353 and $367,982 and $1,948,900 and $1,324,861, respectively. The revenue and gross profit are and have been included in our Services segment since the respective contract acquisition dates.

Periodic Remeasurement of Contingent Liabilities

The fair value of the contingent consideration and pre-acquisition deferred maintenance liabilities are remeasured each reporting period after the acquisition date and any changes in the estimated fair value are reflected as gains or losses in cost of goods sold or general and administrative expense in the condensed consolidated statement of operations.

We performed a remeasurement analysis of the contingent consideration and pre-acquisition deferred maintenance liabilities at September 30, 2025 and determined that the carrying value of the liabilities approximated the estimated fair value of the liabilities, based on a discounted cash flow analysis, and did not record a remeasurement adjustment for the period ended September 30, 2025.

We are unable to provide the pro forma information required under ASC 805-10-50-2(h) as the disclosure is impracticable since the required pre-acquisition historical contract records were not maintained by Aegis in a manner that would allow for an accurate reconstruction of financial performance prior to the acquisitions. Despite reasonable efforts to obtain and validate the necessary data, including a review of the available information that was provided during the acquisition, we were unable to compile reliable financial information that would meet the disclosure requirements under ASC 805.

During the first quarter of 2019, we recognizedtwo individual sales of energy producing assets for a total ofeight power purchase agreements, including the associated energy production contracts, for total consideration of $7 million.

In connection with these assets sales, we entered into agreements with the purchaser to maintain and operate the assets over the remaining periods of the associated energy production contracts (through August 2033 and January 2034, respectively) in exchange for monthly maintenance and operating fees. These agreements contain provisions whereby we have guaranteed to the purchaser a minimum level or threshold of cash flows from the associated energy production contracts. Actual results are compared to the minimum threshold bi-annually and we are contractually obligated to reimburse any shortfall to the purchaser. To the extent actual cash flow results exceed the minimum threshold, we are entitled to 50% of such excess under the agreements. Based upon an analysis of these energy producing assets' expected future performance, as of September 30, 2025, we do not expect to make any material payments under the guarantee.

At June 30, 2025, our obligation under the energy production contracts was $42,089, representing 100% of the cash flows shortfall below the minimum threshold for the bi-annual period ended June 30, 2025. Payment was made in the third quarter of 2025 and our obligation as of September 30, 2025 was $0.

The foregoing agreements also contain provisions whereby we have agreed to make whole the purchaser in the event the counterparty to the energy production contract(s) defaults on or otherwise terminates before the stated expiration of the energy production contract. If we are required to make whole the purchaser under such provisions, we would be entitled to seek recovery from the counterparty to the energy production contract(s) under a similar provision contained in those contracts in respect of early termination.

We are also responsible under the agreements for site decommissioning costs, if any, in excess of certain threshold amounts by site. Decommissioning of site assets is performed when, if and as requested by the counterparty to the energy production contract upon termination of the energy production contract. We review and assess the likelihood and potential liability for decommissioning when sites cease operating. To date, our decommissioning liability exposure has not been material since most customers assume the decommissioning costs in connection with their facility upgrade.

Our leases principally consist of operating leases related to our corporate office, field offices, and our research, manufacturing, and storage facilities. Effective December 19, 2023, we entered into a master finance lease agreement for motor vehicles.

At inception, we determine if an arrangement constitutes a lease and whether that lease meets the classification criteria of a finance or operating lease. Some of our lease agreements contain lease components (e.g. minimum rent payments) and non-lease components (e.g. maintenance, labor charges, etc.). We account for each component separately based on the estimated standalone price of each component.

Operating Leases

Operating leases are included in Right-of-use assets - operating leases, Operating lease obligations, current portion and Operating lease obligations, net of current portion, on the consolidated balance sheets. These assets and liabilities are recognized at the commencement date based on the present value of remaining lease payments over the lease term and using an incremental borrowing rate consistent with the lease terms or implicit rates, when readily determinable. For those leases where it is reasonably certain at the commencement date that we will exercise the option to extend the lease, then the lease term will include the lease extension term. Short-term operating leases, which have an initial term of 12 months or less, are not recorded on the balance sheet.

On March 31, 2023, we entered intotwo lease agreements fortwo adjacent buildings, located in North Billerica, Massachusetts, containing approximately 26,412 square feet of manufacturing, storage and office space to serve as our headquarters and manufacturing facilities. The lease agreements provide for initial lease terms of five (5) years withtwo successive options to renew for additional terms of five (5) years. Both leases commenced on January 1, 2024 and require payment of the base rent, real estate taxes, common maintenance expenses and aggregate deposits of $38,200. Our costs for initial improvements required to the leased premises is estimated to range between $1,125,000 and $1,175,000. As of

September 30, 2025 we have spent $1,141,875 on the required improvements at our North Billerica facility. The estimated straight-line monthly rent expense for the initial term of the lease is approximately $26,962 per month. In accordance with ASC 842-20-30-1, we recorded the lease liability and right-of-use asset using the discount rate for the lease upon the lease commencement date, January 1, 2024.

On January 1, 2024 we extended the lease for our 2,800 square foot Valley Stream, NY service center for an additional three (3) years through December 31, 2026, with an option to renew for an additional term of three (3) years. The straight-line base monthly rent for the extension is $4,560 per month. On February 1, 2024, we entered into a lease agreement for 2,063 square feet of office and storage space in East Syracuse, New York for an initial lease term of three (3) years, expiring on January 31, 2027, with an option for an additional lease term of two (2) years. The straight-line base monthly rent for the initial lease term is $1,891 per month. On June 17, 2024, we extended our lease for our 1,751 square foot Hayward, CA service facility for an additional three (3) years through July 31, 2027. The straight-line monthly rent for the extension is $3,662 per month. On January 15, 2025, we entered into a lease agreement for 2,969 square feet of office and storage space in Easton, MA for an initial term of five (5) years, expiring on January 31, 2030, with an option for an additional lease term of five (5) years. The straight-line base monthly rent for the initial lease term is $2,324 per month. On April 30, 2025, we extended the term of our Windsor, CT service center for an additional two (2) years through March 31, 2027, effective April 1, 2025, for 2,000 square feet of office and storage space, with an option for an additional lease term of two (2) years. The straight-line base monthly rent for the initial lease term is $1,850 per month. On July 1, 2025, we exercised our option and extended the term of our 1,414 square foot Mamaroneck, NY service center for an additional term of five (5) years, expiring on February 28, 2031. The straight-line monthly rent for the additional term is $4,519 for our Mamaroneck, NY service facility

The lease on our former headquarters located in Waltham, Massachusetts which consisted of approximately 43,000 square feet of manufacturing, storage and office space, expired on April 30, 2024. The base monthly rent in 2024 was $44,254.

Lease expense for operating leases, which principally consists of fixed payments for base rent, is recognized on a straight-line basis over the lease term. Operating lease expense for the three and nine months ended September 30, 2025 and 2024 was $149,868 and $447,128 and $164,627 and $631,840, respectively.

Supplemental information related to operating leases for the nine months ended September 30, 2025 and 2024 was as follows:

Supplemental balance sheet information related to operating leases as of September 30, 2025 and December 31, 2024 was as follows:

Finance Leases

Finance leases are included in Right-of-use assets - finance leases, Finance lease obligations, current portion and Finance lease obligations, net of current portion, on the condensed consolidated balance sheets. These assets and liabilities are recognized at the commencement date based on the present value of remaining lease payments over the lease term and using an incremental borrowing rate consistent with the lease terms or implicit rates, when readily determinable. For those leases where it is reasonably certain at the commencement date that we will exercise the option to extend the lease, then the lease term will include the lease extension term. On December 19, 2023, we entered into a master finance lease agreement for motor vehicles. As of September 30, 2025, we have thirty-one (31) vehicles under lease of which eleven vehicles (11) have been added in the nine months ended September 30, 2025.

Lease expense for finance leases for the nine months ended September 30, 2025 and 2024 was as follows:

Supplemental information related to finance leases for the nine months ended September 30, 2025 and 2024 was as follows:

Supplemental balance sheet information related to finance leases as of September 30, 2025 and December 31, 2024 is as follows:

Future minimum lease commitments under non-cancellable operating and finance leases as of September 30, 2025 were as follows:

Stock-Based Compensation

On December 22, 2005, our Board of Directors adopted Tecogen's 2006 Stock Option and Incentive Plan ("2006 Plan") under which the Board of Directors or a committee appointed by the Board of Directors may grant incentive stock options to officers and employees and may grant non-qualified stock options, restricted stock and stock to officers, employees, directors, advisors and consultants. The 2006 Plan was amended at various dates by the Board of Directors to increase the number of shares of common stock reserved for issuance under the Plan to 3,838,750, and, in June 2017, stockholders approved an amendment to extend the termination date of the Plan to January 1, 2026 (2006 Plan as amended, "Amended Plan").

Stock options vest based upon the terms of each individual option grant with an acceleration of the unvested portion of such options upon a change of control event, as defined in the Amended Plan. The options are not transferable except by will or domestic relations order. Under the Internal Revenue Code, the option exercise price per share under the Amended Plan cannot be less than the fair market value of the underlying shares on the date of the grant. Incentive stock options granted to an officer or employee owning more than 10% of the combined voting power of the Company, are required to be exercisable at a price per share equal to 110% of the fair market value of a share on the date of grant. The number of shares remaining available for future issuance under the Amended Plan as of September 30, 2025 was 1,151,068.

During the nine months ended September 30, 2025, we granted non-qualified options to purchase an aggregate of 58,500 shares of common stock to certain employees at prices between $2.14 per share and $8.61 per share under the Amended Plan. The fair value of the options issued in 2025 was $137,413. The weighted-average grant date fair-value of stock options granted in 2025 was $2.35 per share.

On March 8, 2022, our Board of Directors adopted Tecogen's 2022 Stock Incentive Plan ("2022 Plan"), under which the Board of Directors or a committee appointed by the Board of Directors may grant incentive stock options to officers and employees and grant non-qualified stock options, restricted stock, and stock grants to officers, employees, directors, advisors and consultants. We have reserved 3,800,000 shares of our common stock for issuance pursuant to awards under the 2022 Plan. The adoption of the 2022 Plan was approved by our shareholders on June 9, 2022. The 2022 Plan expiresten years from its effective date or March 1, 2032.

Under the 2022 Plan, stock options vest based upon the terms of each individual option grant with an acceleration of the unvested portion of such options upon a change of control event, as defined in the 2022 Plan. The options are not transferable except by will or domestic relations order. Under the Internal Revenue Code, the option exercise price per share under the Amended Plan cannot be less than the fair market value of the underlying shares on the date of the grant. Incentive stock options granted to an officer or employee owning more than 10% of the combined voting power of the Company are required to be exercisable at a price per share equal to 110% of the fair market value of a share on the date of grant. The number of shares remaining available for future issuance under the Plan as of September 30, 2025 was 2,632,856.

During the nine months ended September 30, 2025, we granted non-qualified and incentive stock options to purchase an aggregate of 221,336 shares of common stock to certain employees priced at $8.35 per share under the 2022 Plan. The fair value of the options issued in 2025 was $918,035. The weighted-average grant date fair-value of stock options granted in 2025 was $4.15 per share. Also, during the nine months ended September 30, 2025 we granted restricted stock awards, with respect to 95,808 shares of common stock priced at $8.35 per share and which vest in equal annual installments over thefour year period commencing on the first anniversary of the date of grant.

Stock option activity for the nine months ended September 30, 2025 was as follows:

We used a forfeiture rate of 15% to calculate the shares which are expected to vest in the table above. We use the Black-Scholes option pricing model to determine the fair value of stock options granted as of the date of grant. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs. Expected volatility was calculated based on the average volatility offour comparable publicly traded companies. The average expected life was estimated using the simplified method to determine the expected life based on the vesting period and contractual terms, since we do not have the necessary historical exercise data to determine an expected life for stock options. We use a single weighted-average expected life to value option awards and recognize compensation on a straight-line basis over the requisite service period for each separately vesting portion of the awards. The risk-free interest rate is based on U.S. Treasury zero-coupon issues with a remaining term which approximates the expected life assumed at the date of grant.

The weighted average assumptions used in the Black-Scholes option pricing model for options granted in nine months ended September 30, 2025 and 2024 are as follows:

Consolidated stock-based compensation expense for stock options for the three and nine months ended September 30, 2025 and 2024 was $88,714 and $172,153 and $41,908 and $131,906, respectively. Stock-based compensation for restricted stock awards granted for the three and nine months ended September 30, 2025 was $37,705. No tax benefit was recognized related to the stock-based compensation recorded during the period.

At September 30, 2025, the total compensation cost related to unvested stock options and restricted stock awards not yet recognized is $1,924,038 and this amount will be recognized over a weighted average period of 2.39 years.

On October 9, 2023, we entered into note subscription agreements with each of John N. Hatsopoulos and Earl R. Lewis, III, each a director and shareholder of the Company, pursuant to which Mr. Hatsopoulos agreed to provide financing to us of up to $1,000,000, and Mr. Lewis agreed to provide financing to us of $500,000, and potentially, an additional $500,000 at his discretion. On October 10, 2023, we borrowed $500,000 from Mr. Hatsopoulos and issued him aone-year promissory note with interest accruing at 5.12% per annum. On July 23, 2024, we borrowed an additional $500,000 from Mr. Hatsopoulos, and issued aone-year promissory note with interest accruing at 5.06% per annum. On March 21, 2024, the terms of the promissory note, dated October 10, 2023, we extended the maturity date byone-year, making the maturity date October 10, 2025. On September 18, 2024, we borrowed $500,000 from Mr. Lewis and issued him aone-year promissory note with interest accruing at 4.57% per annum.

On January 14, 2025, we agreed to permit Mr. Lewis to either receive repayment of his note in cash or, at his discretion, convert the balance of the promissory note into shares of our common stock. In the event of such a conversion, the number of shares we were required to be issue is determined by dividing the balance due under the promissory note by the average closing price per share of our shares during thethirty-day period prior to the date of conversion.

On February 18, 2025, we amended the promissory notes with Mr. Hatsopoulos to extend the maturity dates for both promissory notes to July 31, 2026. We also agreed to permit Mr. Hatsopoulos to either receive repayment of his notes in cash, or at his discretion, convert the balance(s) due of one or both of the promissory notes into shares of our common stock. In the event of such a conversion, the number of shares we were required to issue is determined by dividing the balance(s) due under the promissory note(s) by the average closing price per share of our shares during thethirty-day period prior to the date of conversion. Both of the promissory notes with Mr. Hatsopoulos were reclassed to long-term liabilities due to the February 18, 2025 amendment.

The loans are required to be repaid in the event of a change of control of the company and upon the occurrence of an event of default under the note, including upon a failure to pay when due the principal and interest when due, or the commencement of voluntary or involuntary bankruptcy or insolvency proceeding.

The loans and terms of the loan agreements were unanimously approved by our Board of Directors.

The loans bear interest on the outstanding principal at the Internal Revenue Service’s Applicable Federal Rate to be determined at the time we issue a promissory note in connection with a loan draw-down. The notes may be prepaid by us at any time. The principal amount of each loan and accrued interest is subject to mandatory prepayment in the event of a change of control of the registrant. The promissory notes are subject to customary events of default and are transferable provided the conditions to transfer set forth in the promissory notes are satisfied by the noteholder. The proceeds of the loans have been used for general working capital purposes and to fund the initial improvements required at our North Billerica facility.

On May 1, 2025, Mr. Lewis elected to convert the promissory note we issued to him in connection with his loan to us in the principal amount of $500,000 together with $14,148 of accrued and unpaid interest into 240,256 shares of our common stock at a per share price of $2.14. The number of shares was determined by dividing the balance due under the promissory note by the average closing price per share of our shares during thethirty-day period prior to the date of conversion. At September 30, 2025 our obligation to Mr. Lewis under the promissory note was retired.

On September 3, 2025 and September 4, 2025, we paid $548,675 and $528,281, respectively, to Mr. Hatsopoulos in repayment of his loans to us in the aggregate principal amount of $1,000,000 together with $76,956 of accrued and unpaid interest. At September 30, 2025, our obligation to Mr. Hatsopoulos under the promissory notes were retired.

The fair value topic of the FASB Accounting Standards Codification defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The accounting guidance also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value:

Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities. We currently do not have any Level 1 financial assets or liabilities.

Level 2 - Observable inputs other than quoted prices included in Level 1. Level 2 inputs include quoted prices for identical assets or liabilities in non-active markets, quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for substantially the full term of the asset or liability. We have Level 2 financial assets as provided below.

Level 3 - Unobservable inputs reflecting management’s own assumptions about the input used in pricing the asset or liability. We have Level 3 liabilities as provided below.

Marketable equity securities

The following tables present the asset reported in "other assets" in the condensed consolidated balance sheet measured at its fair value on a recurring basis as of September 30, 2025 and 2024 by level within the fair value hierarchy.

We utilize a Level 2 category fair value measurement to value our investment in EuroSite Power, Inc. as a marketable equity security at period end. That measurement is equal to the quoted market closing price at period end. Since this security is not actively traded we classify it as Level 2.

The following table summarizes changes in Level 2 assets which are comprised of marketable equity securities for the three and nine months ended September 30, 2025 and 2024:

Contingent Contract Consideration

We utilize a Level 3 category fair value measurement to value the agreed upon Aegis contingent contract consideration liability at period end since there are no quoted prices for this liability in non-active markets, there are no quoted prices for similar liabilities in active markets and there are no inputs that are observable for substantially the full term of the the liability. The contingent contract consideration calculation requires management to make estimates and assumptions that affect the reported amount of the liability. The contingent contract consideration is payable each calendar quarter through the earlier of the expiration or termination of the relevant maintenance agreements, or the seventh (7th) anniversary of the acquisition date. The consideration is equal to the product of the revenues collected in a calendar quarter multiplied by an applicable percentage. The agreement stipulates quarterly aggregate revenue targets and an applicable percentage, and provides for a higher applicable percentage if revenues exceed the target revenues. The applicable percentage ranges from 5% to 10% over the agreement term. On the date of acquisition, the fair value of the contingent consideration was calculated using a weighted average cost of capital of 15%, discounting the future cash flows to present value.

Our Chief Executive Officer, who is our Chief Operating Decision Maker ("CODM"), manages our business through three operating segments, wherein our CODM manages our businesses by: (i) assessing operating performance on a periodic basis; (ii) making resource allocation decisions; and (iii) designating responsibilities for his direct reports. As of September 30, 2025, we were organized into three operating segments through which senior management evaluates our business. These segments, as described in more detail in "Note 1. Description of Business and Basis of Presentation", are organized around the products, services and energy production provided to customers and represent our reportable segments.

Our CODM uses segment profit, based on operating income after the elimination of intercompany transactions and segment identifiable assets to assess segment operating performance and to make resource allocation decisions. Certain costs such as other income (expense) are not included in the measure of segment profit and are excluded from management's assessment of segment financial performance.

Corporate includes finance, treasury, certain research and development costs, tax and legal costs and certain other costs which are not allocated to the reportable segments.

The following table presents information by reportable segment for the three and nine months ended September 30, 2025 and 2024:

We have evaluated events through the date of this filing, and, except as described below, have determined that no material subsequent events occurred that would require recognition in the consolidated financial statements or disclosure in the notes thereto.