TECOGEN INC

The Company has determined not to include a summary of the information permitted by Item 16 of the Form 10-K.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Abinand Rangesh, with the power of substitution and re-substitution, as his or her attorney-in-fact and agent, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments to this Annual Report on Form 10-K for the year ended December 31, 2023, and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming that said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

Contents

Report of Independent Registered Public Accounting Firm F-2

Consolidated balance sheets F-4

Consolidated statements of operations F-5

Consolidated statements of stockholders' equity F-6

Consolidated statements of cash flows F-7

Notes to the consolidated financial statements F-9

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To the Board of Directors and Stockholders of Tecogen Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Tecogen Inc. (the “Company”) as of December 31, 2023 and 2022, the related consolidated statements of operations, stockholders' equity, and cash flows, for the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2023 and 2022, and the results of its operations and its cash flows for the years then ended, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting, but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing separate opinions on the critical audit matter or on the accounts or disclosures to which it relates.

Contingent consideration and customer contracts

Description of the Matter

As discussed in Notes 5 and 8 to the financial statements, the Company entered into an agreement during the year ended December 31, 2023 to assume certain maintenance agreements and purchase certain assets. The Company’s acquisition accounting for the agreement as a business combination required management to estimate the fair value of contingent consideration and customer contracts. The valuation methodologies applied by management include significant unobservable inputs and assumptions based on management judgments.

How We Addressed the Matter in Our Audit

Our audit procedures relating to the valuation of the contingent consideration and customer contracts included, but were not limited to, reading the executed agreement to understand contractual terms and evaluating the methods and significant assumptions used by the Company in its valuation calculations. We obtained the valuation calculations, performed tests of mathematical accuracy and tests over the completeness and accuracy of underlying data supporting significant assumptions and inputs for consistency with contractual terms. We also engaged a valuation specialist to assist in our assessment of

F- 2 methodologies applied by the Company as well as the significant inputs and assumptions critical to the conclusions in the valuations, such as existing contract run-out and renewals, forecasted revenues and cash flows and discount rates applied.

/s/WOLF & COMPANY, P.C.

PCAOB ID 392

We have served as the Company's auditor since 2014.

Boston, Massachusetts

March 25, 2024

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As of December 31, 2023 and 2022

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F- 5

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

F- 6

Supplemental disclosure of cash flow information:

F- 7

Note 1. Nature of Business and Operations

Tecogen Inc. (together with its subsidiaries "we", "our", "us" or "Tecogen"), a Delaware Corporation, was incorporated on September 15, 2000, and acquired the assets and liabilities of the Tecogen Products division of Thermo Power Corporation. 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 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 as described above. 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.

Liquidity, Going Concern and Management's Plans

The consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting

principles assuming that we will continue as a going concern, which contemplates the realization of assets and the settlement of obligations in the normal course of business. As of December 31, 2023, our cash and cash equivalents were $1,351,270, compared to $1,913,969 at December 31, 2022, a decrease of $562,699. For the year ended December 31, 2023 we used $823,315 in cash from operations and generated net operating losses of $4,413,612, due to due to lower Products sales, a decrease in gross margin due to higher products material costs and the increased provision for obsolete inventory and an increase in operating expenses due primarily to increased bad debt expense and a general increased in other administrative expenses. Working capital at December 31, 2023 was $9,822,546, compared to $14,344,288 at December 31, 2022, a decrease of $4,521,742 and our accumulated deficit was $42,879,656.

As a result of the above factors, management has performed an analysis to evaluate the entity’s ability to continue as a going concern for one year after the financial statements issuance date. Management’s analysis includes forecasting future revenues, expenditures and cash flows, taking into consideration past performance as well as key initiatives recently undertaken. Our forecasts are dependent on our ability to maintain margins based on the Company's ability to close on new and expanded business, leverage existing working capital, and effectively manage expenses. New and expanded business includes the sale and shipment of newly developed hybrid-drive air-cooled chillers and the acquisition of additional maintenance contracts in February 2024 (see Note 20. "Subsequent Events"). Our backlog at December 31, 2023 was $7,388,145, which is an increase of $666,007 from the December 31, 2022 backlog. We may also be required to borrow funds under note subscription agreements with related parties (see Note 11. "Related Party Notes"). Based on management's analysis, we believe that cash flows from operations and the note agreements will be sufficient to fund operations over the next twelve months. There can, however, be no assurance we will be able to do so. Based on our analysis, the consolidated financial statements do not include any adjustments to the carrying amounts and classification of assets, liabilities, and reported expenses that may be necessary if we were unable to continue as a going concern.

Note 2. Summary of Significant Accounting Policies

Principles of Consolidation and 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 generally accepted accounting principles, or GAAP, to ensure financial condition, results of operations, and cash flows are consistently reported. References to 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 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/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/loss. The same methodology is used to determine

F- 8 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 December 31, 2023.

Investments in partnerships and companies in which we do not have a controlling financial interest but where we have significant influence, if any, are accounted for under the equity method.

Noncontrolling interests in the net assets and operations of ADGNY are reflected in the caption “Noncontrolling interest” in the accompanying consolidated financial statements. All intercompany transactions have been eliminated.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America 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.

Employee Retention Credit

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was signed into law providing numerous tax provisions and other stimulus measures, including an employee retention credit (“ERC”), which is a refundable tax credit against certain employment taxes. The Taxpayer Certainty and Disaster Tax Relief Act of 2020 and the American Rescue Plan Act of 2021 extended and expanded the availability of the ERC.

We qualified for the ERC in the first, second and third quarters of 2021 because our gross receipts decreased by more than 20% from the first, second and third quarters of 2019. As a result of averaging 100 or fewer full-time employees in 2019, all wages paid to employees in the first, second and third quarters of 2021, excluding the wages that were applied to the Paycheck Protection Loan Second Draw, were eligible for the ERC. Wages used towards PPP loan forgiveness cannot be used as qualified wages for purposes of the ERC.

During the three months ended June 30, 2021, we recorded an ERC benefit for the first and second quarters of 2021 of $713,269 and, in the three months ended September 30, 2021 we recorded an ERC benefit for the third quarter of 2021 of $562,752, respectively, in other income (expense), net in the our condensed consolidated statements of operations. A current receivable in the amount of $46,148 is included in our condensed consolidated balance sheet as of December 31, 2023. We have collected all of the other ERC benefits.

Concentration of Credit Risk

Financial instruments that expose us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. We maintain our cash balances in bank accounts, which at times may exceed the Federal Deposit Insurance Corporation’s general deposit insurance limits. The amount on deposit at December 31, 2023 and 2022 which exceeded the $250,000 federally insured limit were approximately $1,009,094 and $1,393,823, respectively. We have not experienced any losses in such accounts and thus believe that we are not exposed to any significant credit risk on cash.

There wasno customer who represented 10% of revenues for the years ended December 31, 2023 and December 31, 2022. There wasone customer who represented 14% of the accounts receivable balance as of December 31, 2023, andone customers who represented 15% of the accounts receivable balance as of December 31, 2022.

Cash and Cash Equivalents

We consider all highly liquid instruments with an original maturity date of three months or less when purchased to be cash and cash equivalents. We have cash balances in certain financial institutions in amounts which occasionally exceed current federal deposit insurance limits. The financial stability of these institutions is continually reviewed by senior management. We believe that we are not exposed to any significant credit risk on cash and cash equivalents.

Accounts Receivable

On January 1, 2023, we adopted ASU 2016-13, Financial Instruments, Credit Losses (Topic 326). Accounts receivable are stated at the amount management expects to collect from outstanding balances. The allowance for credit losses is estimated based on historical experience, aging of the receivable, the counterparty’s ability to pay, condition of general economy and industry, andcombined with management's estimate of current conditions, reasonable and supportable forecasts of future losses to determine estimated credit losses in our evaluation of outstanding accounts receivable at the end of the year. . The allowance for credit losses reflects managements evaluation of our outstanding accounts receivable at the end of the year and our best estimate of probable losses inherent in the accounts receivable balance. Accounts receivable deemed uncollectible are charged against the allowance for credit losses when identified. Our bad debt expense increased to $902,432 in the year ended December 31, 2023, compared to a benefit of $70,987 in the year ended December 31, 2022, due to the write down of certain

F- 9 install receivables which were deemed uncollectible in the year ended December 31, 2023. At December 31, 2023 and 2022, the allowance for credit losses was $149,922 and $361,197, respectively.

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 and anticipated usage. Any reserves that result from this review are charged to cost of sales.

Property, Plant and Equipment

Property, plant and equipment are recorded at cost. Depreciation is provided using the straight-line method over the estimated useful life of the asset, which range from three tofifteen years. Leasehold improvements are amortized using the straight-line method over the lesser of the estimated useful lives of the assets or the term of the related leases. Expenditures for maintenance and repairs are expensed, while renewals and betterments that materially extend the life of an asset are capitalized.

We review our property, plant and equipment for potential impairment whenever events or changes in business circumstances indicate that the carrying value of the assets may not be fully recoverable or that the useful lives of the assets are no longer appropriate. We evaluate the recoverability of our long-lived assets when impairment is indicated by comparing the net book value of the asset group to the estimated future undiscounted cash flows attributable to such assets. If the sum of the projected undiscounted cash flows (excluding interest charges) is less than the carrying value of the assets, the assets will be written down to the estimated fair value and such loss is recognized in income from continuing operations in the period in which the determination is made. If impairment is indicated, the asset is written down to its estimated fair value.

Intangible Assets

Intangible assets subject to amortization include costs incurred by us to acquire product certifications, certain patent costs, developed technologies, and customer contracts. These costs are amortized on a straight-line basis over the estimated economic life of the intangible asset. Indefinite life intangible assets such as trademarks are recorded at cost and not amortized.

The favorable contract asset which relates to existing ADGE customer contracts is more fully described in Note 8. "Intangible Assets and Liabilities other than Goodwill". Customer contracts are more fully described in Note 5. "Aegis Contract and Related Asset Acquisition".

Impairment of Long-lived Assets

Long-lived assets, including intangible assets and property, plant and equipment, are evaluated for impairment whenever events or changes in circumstances have indicated that an asset may not be recoverable and are grouped with other assets to the lowest level for which identifiable cash flows are largely independent of the cash flows of other groups of assets and liabilities. If the sum of the projected undiscounted cash flows (excluding interest charges) is less than the carrying value of the assets, the assets will be written down to the estimated fair value and such loss is recognized in income from continuing operations in the period in which the determination is made. Management determined that an impairment of $4,674 of long-lived assets existed as of December 31, 2022, respectively.

For the year ended December 31, 2022, we recorded impairment of long-lived assets as follows:

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

F- 10 acquisition related liabilities, if applicable, for any contingent consideration or deferred payments to the seller. Contingent consideration is recorded at fair value on the acquisition date based on our expectation of achieving the contractually defined revenue targets. The fair value of the contingent consideration liabilities is remeasured each reporting period after the acquisition date and any changes in the estimated fair value are reflected as gains or losses in general and administrative expense in the consolidated statement 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.

Goodwill

Goodwill is the excess of the fair value of consideration paid for businesses over the fair value of the identifiable net assets acquired. Impairment testing for goodwill is performed annually, generally in the fourth fiscal quarter, or more frequently if impairment indicators are present.

To determine if goodwill is potentially impaired, we have the option to perform a qualitative assessment. However, we may elect to bypass the qualitative assessment and perform an impairment test even if no indications of a potential impairment exist. The impairment test for goodwill is performed at the reporting unit level and compares the fair value of the reporting unit (calculated using a discounted cash flow method) to its carrying value, including goodwill. The discount rate represents our estimate of the weighted-average cost of capital, or expected return, that a marketplace participant would have required as of the valuation date. If the carrying value exceeds the fair value, an impairment charge is recorded for the excess carrying value over fair value, limited to the total amount of goodwill of that reporting unit. Our assessment in 2023 indicated that the carrying value of our energy production reporting unit and the Aegis maintenance contracts did not exceed their fair value and therefore goodwill was not impaired. (see Note 10."Goodwill").

We adopted the provisions of ASU 2017-04, during 2018, which simplified the impairment testing process by eliminating the requirement to determine the implied fair value of goodwill. We test goodwill for impairment on either a qualitative basis under certain conditions, or a quantitative basis. On a quantitative basis, fair value of the reporting units is primarily determined using a probability weighted discounted cash flow analysis.

Leases

On January 1, 2019, we adopted the guidance under ASU No. 2016-02, “Leases” ("ASC 842”). ASC 842 requires lessees to recognize most leases on their balance sheets as a right-of-use ("ROU") asset with a corresponding lease liability. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Lease ROU assets and liabilities are recognized at lease commencement date based on the present value of lease payments over the expected lease term. See Note 14."Leases".

Income (loss) per Common Share

We compute basic income (loss) per share by dividing net income (loss) for the period by the weighted-average number of shares of common stock outstanding during the period. We compute our diluted earnings per common share using the treasury stock method. For purposes of calculating diluted earnings per share, we consider our shares issuable in connection with the convertible debentures, stock options and warrants to be dilutive common stock equivalents when the exercise/conversion price is less than the average market price of our common stock for the period.

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.

Income Taxes

We use the asset and liability method of accounting for income taxes. The current or deferred tax consequences of transactions are measured by applying the provisions of enacted tax laws to determine the amount of taxes payable currently or in future years. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities and expected future tax consequences of events that have been included in the financial statements or tax returns using enacted tax rates in effect for the years in which the differences are expected to reverse. Under this method, a valuation allowance is used to offset deferred taxes if, based upon the available evidence, it is more likely than

F- 11 not that some or all of the deferred tax assets may not be realized. Management evaluates the recoverability of deferred taxes and the adequacy of the valuation allowance annually.

We have adopted the provisions of the accounting standards relative to accounting for uncertainties in tax positions. These provisions provide guidance on the recognition, derecognition and measurement of potential tax benefits associated with tax positions. We elected to recognize interest and penalties related to income tax matters as a component of income tax expense in the statements of operations. We have analyzed our current tax return compliance positions and determined that no uncertain tax positions have been taken that would require recognition.

With few exceptions, we are no longer subject to possible income tax examinations by federal, state or local taxing authorities for tax years before 2020, with the exception of loss carryforwards in the event they are utilized in future years. Our tax returns are open to adjustment from 2002 forward, as a result of the fact that the we have loss carryforwards from those years, which may be adjusted in the year those losses are utilized.

Fair Value of Financial Instruments

Our financial instruments are cash and cash equivalents, accounts receivable, available-for-sale securities and accounts payable. The recorded values of cash and cash equivalents, accounts receivable and accounts payable approximate their fair values based on their short-term nature. See Note 16. "Fair Value Measurements".

Revenue Recognition

Revenue is recognized when performance obligations under the terms of a contract with our 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 a sales transaction are recorded in revenue and shipping and handling costs incurred are recorded in general and administrative expenses. For the years ended December 31, 2023 and 2022, $427,880 and $563,482 of shipping and handling costs were included in general and administrative expenses in the accompanying consolidated statements of operations, respectively. We elected to exclude from revenue any value-add sales and other taxes which we collect concurrent with revenue-producing activities. These accounting policy elections are consistent with the manner in which we have historically recorded shipping and handling fees and taxes. Incremental costs incurred by us in obtaining a contract with a customer are negligible, if any, and are expensed ratably in proportion to the related revenue recognized.

Advertising Costs

We expense the costs of advertising as incurred. For the years ended December 31, 2023 and 2022, advertising expense was approximately $79,000 and $51,000, respectively.

Research and Development Costs

Research and development expenditures are expensed as incurred. Our total research and development expenditures were approximately $840,000 and $733,000 for the years ended December 31, 2023 and 2022, respectively.

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date, based on the estimated fair value of the award, and is recognized as an expense in the statements of operations over the requisite service period.

The determination of the fair value of share-based payment awards is affected by our stock price. For the awards issued prior to our being publicly traded, we considered the sales price of the Common Stock in private placements to unrelated third parties as a measure of the fair value of its Common Stock.

We utilize actual forfeitures when calculating the expense for the period. Stock-based compensation expense recognized is based on awards that are ultimately expected to vest. We evaluate the assumptions used to value awards regularly and if factors change and different assumptions are employed, stock-based compensation expense may differ significantly from what has been recorded in the past. If there are any modifications or cancellations of the underlying unvested securities, we may be required to accelerate, increase or cancel any remaining unearned stock-based compensation expense.

See Note 15."Stockholders' Equity" for a summary of the restricted stock and stock option activity under our stock-based employee compensation plan for the years ended December 31, 2023 and 2022.

Disaggregated Revenue

In general, our business segmentation are 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.

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The following table further disaggregates our revenue by major source by segment for the years ended December 31, 2023 and 2022.

Products Segment

Products. Our Product 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 the customer takes ownership of the product. Payment terms on product sales are generally 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. 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 acquisition of the Aegis maintenance contracts and related business closed on March 15, 2023 and since April 1, 2023, revenues resulting from the Aegis acquisition have been included in our revenue from the Services segment.. Payment terms for maintenance services are generally 30 days.

Installation Services. Prior to January 1, 2023, we provided installation services which included all necessary engineering and design, labor, subcontract labor and service to install a cogeneration unit including integration into the

F- 13 customers’ existing electrical and mechanical systems. Since January 1, 2023, we have not provided material installation services and do not expect to provide material installation services going forward.

Energy Production Segment

Energy Production. 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 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 consolidated balance sheets.

We did not recognize any revenue during the year ended December 31, 2023 that was included in unbilled revenue as of December 31, 2023. Approximately $16,428 of revenue was billed in this period that had been recognized in previous periods.

Revenue recognized during the year ended December 31, 2023 that was included in deferred revenue at the beginning of the period was $837,571.

Remaining Performance Obligations

Remaining performance obligations related to ASC 606 represent the aggregate transaction price allocated to performance obligations with an original contract term 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 bill customers. Remaining performance obligations therefore consist of unsatisfied or partially satisfied performance obligations related to fixed price maintenance contracts and installation contracts.

As of December 31, 2023, the aggregate amount of the transaction price allocated to remaining unsatisfied performance obligations was approximately $2,016,817. We expect to recognize revenue of approximately 95% of the remaining performance obligations over the next 24 months,13% recognized in the first 12 months and 82% recognized over the subsequent 12 months, and the remainder recognized thereafter.

Significant New Accounting Standards Adopted this Period

New accounting standards adopted in the year ended December 31, 2023.

Financial Instruments, Credit Losses (Topic 326). In June 2016, the Financial Accounting Standards Board issued ASU No. 2016-13, Financial Instruments, Credit Losses (Topic 326), which was subsequently amended by ASUs 2018-19, 2019-04, 2019-05, 2019-11, and 2020-03. Topic 326 replaces the existing incurred loss impairment model with a methodology that incorporates all expected credit loss estimates, resulting in more timely recognition of losses. Under Topic 326, we are required to measure all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported financial assets. It also requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses. We adopted Topic 326 on January 1, 2023 on a modified retrospective basis. The adoption did not have a material effect on our consolidated financial statements.

Recently Issued Accounting Pronouncements

Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures. In November 2023, the Financial Accounting Standards Board issued ASU 2023-07, Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures. The new standard requires enhanced disclosures about a public entity's reportable segments including more

F- 14 detailed information about a reportable segment's expenses. The amendments in this update apply to all public entities that are required to report segment information, and include those entities that have a single reportable segment. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. We are currently evaluating the impact on our consolidated financial statements and related disclosures.

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. We are is currently evaluating the impact on our consolidated financial statements and related disclosures.

Note 3. Income (loss) per Common Share:

Basic and diluted loss per common share for the years ended December 31, 2023 and 2022, respectively, was as follows:

Note 4. Acquisition of American DG Energy Inc.

On May 18, 2017, we completed our acquisition, by means of a stock-for-stock merger, of 100% of the outstanding common shares of American DG Energy Inc. (“American DG Energy" or "ADGE”), a company which installed, owned, operated and maintained complete distributed generation of electricity systems, or DG systems or energy systems, and other complementary systems at customer sites and sells electricity, hot water, heat and cooling energy under long-term contracts at prices guaranteed to the customer to be below conventional utility rates, by means of a merger of one of our wholly owned subsidiaries with and into ADGE such that ADGE became a wholly owned subsidiary of Tecogen. We acquired ADGE to, among other reasons, expand our product offerings and benefit directly from the long-term contracted revenue streams generated by these installations. We gained control of ADGE on May 18, 2017 by issuing shares of our Common Stock to the prior stockholders of ADGE.

Goodwill of $13.3 million arising from the acquisition is primarily attributable to the going concern element of ADGE’s business, including its assembled workforce and the long-term contractual nature of its business, as well as expected cost synergies from the merger related primarily to the elimination of administrative overhead and duplicative personnel. None of the goodwill recognized is expected to be deductible for income tax purposes.

The favorable contract asset and the unfavorable contract liability, both of which relate to existing customer contracts, and the estimated amortization are more fully described in Note 8. "Intangible Assets and Liabilities other than Goodwill".

Note 5. Aegis Contract and Related Asset Acquisition

On March 15, 2023, we entered into an agreement ("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 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

F- 15 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 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 have the right to acquire and assume additional Aegis’ maintenance agreements for cogeneration systems on substantially similar terms and conditions. The 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 Agreement to add eighteen (18) additional maintenance contracts (the "Amendment"). The Amendment 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.

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 included the financial results of the Aegis maintenance agreements in our consolidated financial statements from April 1, 2023, the closing or acquisition date.

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

The amounts initially recognized for inventory, identifiable intangible assets, contingent consideration and deferred maintenance reserves we 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 have completed our analysis and valuation are have recorded the following adjustments to the initial valuations:

•decreased accounts payable assumed and inventory acquired by $20,130, which had no impact on goodwill balance;

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•decreased contingent consideration by $185,805 due to assigned sites which had ceased operations, as of our prior to the acquisition date, and due to customers who declined the assignment of the maintenance contract. We also amended our discount rate assumption which reduced future cash flows;

•increased identifiable intangible assets by $181,333 due to the addition of contract run out periods; and,

•the excess of cost over fair value of net assets acquired decreased $385,723.

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.

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 consolidated statements of operations and will not impact the goodwill balance. At December 31, 2023, we remeasured the contingent consideration and deferred maintenance reserves, however no adjustment was recorded given the probability of achieving the revenue estimates and deferred maintenance costs were consistent with our initial valuation.

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 a three-year period from the date of acquisition, to repair customer equipment that had not been properly maintained prior to our acquisition of the maintenance service agreements.

Revenues and gross profit from the Aegis maintenance contracts since the acquisition date were $1,884,891 and $1,167,225, respectively, for the year December 31, 2023 and are included in our Services segment. For the year December 31, 2023, the contingent consideration payable to Aegis amounted to $94,245, of which $61,275 was paid in 2023 and the balance was paid in mid-February 2024. We 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 information could not be obtained from the acquiree.

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 on recurring internal resources were de minimus and such costs were expensed as incurred (ASC 805-50-30-1).

The following table summarizes the contract-related liabilities assumed as of December 31, 2023:

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Note 6 . Sale of Energy Producing Assets and Goodwill Impairment

During the first quarter of 2019, we sold certain energy producing assets, including the associated energy production contracts for total consideration of $7 million.

In connection with the asset 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 fees for both maintenance and operation. 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 reimburse any shortfall to the purchaser. To the extent actual results are in excess of the minimum threshold, we are entitled to fifty percent of such excess under the agreements. We received excess payments in both the years ended December 31, 2023 and 2022. For the year ended December 31, 2023, we recognized $25,633 of revenue representing our share of the excess cash flows under the energy production contacts, the current receivable which is included in our consolidated balance sheet as of December 31, 2023.

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. Should we be 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 did not recognize any counterparty contract default costs in the years ended December 31, 2023 and 2022.

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 did not recognize any site decommissioning costs in the years ended December 31, 2023 and 2022 .

Note 7. Inventory, net

Inventory at December 31, 2023 and 2022 consisted of the following.

Note 8. Intangible Assets and Liabilities Other Than Goodwill

During the year ended December 31, 2022 we capitalized $11,615 of product certification costs and $17,890 of patent-related costs. Also included in intangible assets are legal costs incurred by us to obtain patents for our intellectual property. These patents, once they are placed in service, are amortized on a straight-line basis over the estimated economic life of the associated product, which ranges from approximately 7-10 years. We did not capitalize any cost incurred for product certification costs, patent-related costs or trademarks during the year ended December 31, 2023.

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Intangible assets and liabilities at December 31, 2023 and 2022 consist of the following:

The aggregate amortization expense related to intangible assets and liabilities exclusive of unfavorable contract related intangibles was $333,676 and $201,043 during the years ended December 31, 2023 and 2022, respectively. The net credit to cost of sales related to the amortization of the contract related intangible asset and liability for the years ended December 31, 2023 and 2022 was $220,823 and $274,112, respectively.

Contract Asset and Liability

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 (see Note 4. "Acquisition of American DG Energy Inc."). The customer contract asset includes the maintenance agreements contracts acquired by us on April 1, 2023 as part of the Aegis acquisition (See Note 5. "Aegis Contract and Related Asset Acquisition".

During the year ended December 31, 2022, we determined that certain of the ADGE customer contracts terminated due to the customers failure to perform their obligations pursuant to the contractual agreements and accordingly reversed $151,981 of unfavorable contract liability related to these contacts. The adjustments are included in the consolidated statement of operations for the year ended December 31, 2022, as non-cash benefits within long-lived asset impairment.

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 approximately 1-11 years, and is charged against cost of sales in the accompanying consolidated statement of operations. Aggregate future amortization over the next five years is estimated to be as follows:

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Note 9. Property, Plant and Equipment, net

Property, plant and equipment at December 31, 2023 and 2022 consisted of the following:

*Lesser of estimated useful life of asset or lease term

Depreciation and amortization expense on property and equipment for the years ended December 31, 2023 and 2022 was $454,859 and $501,418, respectively. During the year ended December 31, 2023, we received proceeds of $34,655 from the disposition of certain assets and reversed $8,687 of accrued decomissioning costs from a former ADG energy site, realizing a gain of $36,207. During the year ended December 31, 2022 , we received proceeds of $72,655 from the disposition of certain assets, realizing a gain of $41,931.

During the year ended December 31, 2022, we determined that three of the ADGE customer contracts terminated due to the customers failure to perform their obligations pursuant to the contractual agreements and deemed the assets related to the contracts at these sites to be impaired. We recorded a non-cash impairment of $156,655 which is included in the consolidated statement of operations for the year ended December 31, 2022, within long-lived asset impairment.

During the year ended December 31, 2023 there were no ADGE contract terminations.

Note 10. Goodwill

Changes in the carrying amount of goodwill by reportable segment during the years ended December 31, 2023 and 2022 was as follows:

We performed a goodwill impairment test at December 31, 2023 and determined that the estimated fair value of the of the assets, based on a discounted cash flow analysis, exceeded the carrying value of the assets and did not record a goodwill impairment for the year 2023.

See Note 6. "Sale of Energy Producing Assets and Goodwill Impairment" and Note 5. "Aegis Contract and Related Asset Acquisition" for further discussion.

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Note 11. Related Party Notes

On October 9, 2023, we entered into note subscription agreements with each of John N. Hatsopoulos, a director and principal shareholder of registrant, and Earl R. Lewis, III, a director of registrant, pursuant to which Mr. Hatsopoulos agreed to provide financing to us of up to $1 million, and Mr. Lewis agreed to provide financing to us of $500,000, and potentially, an additional $500,000 at his discretion. We have the right to determine the amount of the loans at the time of a draw down, subject to the conditions in our agreements with each of Mr. Hatsopoulos and Mr. Lewis discussed below. 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 drawdown. The principal amount and accrued interest of each loan is repayable one year from the date of issuance of the applicable promissory note. A note 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 are expected to be used for general working capital purposes.

On October 10, 2023, we issued a promissory note and borrowed $500,000 from Mr. Hatsopoulos. The loan bears interest at 5.12% per annum. At December 31, 2023 our obligation to Mr. Hatsopoulos under the promissory note, inclusive of $5,505 of accrued and unpaid interest, was $505,505. On March 21, 2024, John H. Hatsopoulos amended the terms of the promissory note, dated October 10, 2023, extending the maturity date by one year, making the maturity date October 10, 2025 and agreeing to accept payment in cash or Tecogen Inc. common stock.

Note 12. Commitments and Contingencies

Operating Lease Obligations

We lease office space and warehouse facilities under various lease agreements which expire through January 2031. Total rent expense for the years ended December 31, 2023 and 2022 amounted to $812,515 and $811,664, respectively. See Note 14. "Leases" for further discussion.

Finance Lease Obligations

We lease motor vehicles under a master vehicle lease agreement, effective December 19, 2023, which expire through December 2028. See Note 14. "Leases" for further discussion.

Legal Matters

On November 23, 2022, we were served with a suit filed against us on August 24, 2022 in the Ontario Superior Court of Justice by The Corporation of the Town of Milton, Milton Energy Generation Solutions Inc. and Milton Hydro Distribution Inc (the "Plaintiffs"), all of whom are municipal corporations incorporated in the Province of Ontario. The plaintiffs sued for damages in the amount of CDN $1,000,000, pre-judgment and post-judgment interest, legal fees, and any further relief the court may deem, alleging breach of contract, breach of warranty, negligent misrepresentations and nuisance. Plaintiffs allege that on or about July 10, 2022, a Tecogen cogenerator installed by us at the plaintiffs facility caught fire, causing damage to the cogenerator and the plaintiff's facility. We have filed a response denying liability and are being represented by Canadian counsel. For the year ended December 31, 2022, we reserved $150,000 for anticipated damages which may not be covered by our insurance and continue to maintain the reserve at December 31, 2023.

Guarantees

In connection with the sale of energy producing assets, we made certain guarantees to the purchaser as discussed in Note 5. "Sale of Energy Producing Assets and Goodwill Impairment." Based upon an analysis of these energy producing assets expected future performance, as of December 31, 2023 we do not expect to make any material payments under the guarantee.

Change in Control Severance Benefit Plan

On July 9, 2020, our compensation committee of the board of directors adopted the Tecogen Inc. Change in Control Severance Benefit Plan ("Plan"). The Plan provides for up to 12 months of severance benefits for certain of our key management employees who are selected as plan participants by the plan administrator and who have executed a Change in Control Severance Benefit Plan Participation Notice. On July 9, 2020, Robert A. Panora, our President and Chief Operating Officer, and John K. Whiting, IV, our General Counsel and Secretary, were each designated as participants in the Plan.

Under the Plan, upon the occurrence of certain termination events following a change in control of the Company, the executive participants would receive cash severance payments equal to 12 months’ salary and bonus payments, continuation of certain health benefits, the acceleration of bonus awards, and immediate vesting of outstanding unvested options (including

F- 21 performance options) to acquire our common stock. The severance payments are required to be paid in a single lump sum. The Plan has a term ofthree years and will automatically extend for successive additionalone-year terms unless we provide written notice at leastsix months in advance of a then current term.

An executive will be entitled to severance under the Plan only if there has been a “Change in Control” of the Company and the termination of employment or service occurs during the period that isthree months prior to and 18 months following a change in control of the Company. Also, a participant's employment with the Company may be terminated by a participant for “Good Reason” or be an “Involuntary Termination Without Cause” by the Company, as those terms are defined in the Plan. In order to be eligible to receive severance benefits under the Plan, an executive must comply with the terms of the Plan, including the release of claims in favor of the Company and certain confidentiality, non-compete, non-solicitation, and non-disparagement covenants during and following termination of employment. The Plan will be administered by the compensation committee of the board of directors (or by the full board of directors or such other committee as the board may designate).

Note 13. Product Warranty

We reserve an estimate of our exposure to warranty claims based on both current and historical product sales data and warranty costs incurred. The majority of our products are sold with aone-year warranty. We assesses the adequacy of our recorded warranty liability periodically and adjust the reserve as necessary. The warranty liability is included in accrued expenses on the accompanying consolidated balance sheets.

Changes in our warranty reserve were as follows:

Note 14. Leases

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, Lease obligations, current and Long-term liabilities - 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. Short-term operating leases, which have an initial term of 12 months or less, are not recorded on the balance sheet.

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 years ended December 31, 2023 and 2022 was $812,515 and $811,664, respectively. Lease expense for finance leases, consisting of fixed payments for base rent and initial costs for the year ended December 31, 2023 was $2,338.

Supplemental information related to operating leases for the years ended December 31, 2023 and 2022 was as follows:

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Finance Leases

Finance leases are included in Right-of-use assets, Lease obligations, current and Long-term liabilities - 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. Short-term operating leases, which have an initial term of 12 months or less, are not recorded on the balance sheet.

Supplemental information for finance leases for the year ended December 31, 2023 is as follows:

Supplemental balance sheet information related to operating leases for the years ended December 31, 2023 and 2022 was as follows:

Supplemental balance sheet information related to finance leases for the year ended December 31, 2023 is as follows:

Future minimum lease commitments under non-cancellable operating and finance leases as of December 31, 2023 were as follows:

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Operating Lease - Commencement date January 1, 2024

On March 31, 2023, we entered into two lease agreements for two adjoining buildings, located in 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 with two successive options to renew for additional terms of five (5) years. Both leases commence 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 $500,000 and $750,000. 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 will record the lease liability and right-of-use asset using the discount rate for the lease upon the lease commencement date, January 1, 2024.

Future minimum lease commitments under the two lease agreements which commenced on January 1, 2024 were as follows:

Note 15. Stockholders’ Equity

Common Stock

The holders of our Common Stock have the right to vote their interest on a per share basis. At December 31, 2023 and 2022, there were 24,850,261 shares of our Common Stock outstanding.

Preferred Stock

On February 13, 2013, we authorized 10 million shares of preferred stock. As of December 31, 2023, no preferred shares were issued or outstanding.

Stock-Based Compensation

We adopted the 2006 Stock Option and Incentive Plan (the “Plan”), under which the board of directors may grant incentive or non-qualified stock options and stock grants to key employees, directors, advisors and our consultants. The Plan was amended at various dates by the Board of Directors to increase the reserved shares of common stock issuable under the Plan to 3,838,750 as of December 31, 2023, and in June 2017 stockholders approved an amendment to extend the termination date of the Plan to January 1, 2026 and to ratify all of our option grants issued after January 1, 2016 (the “Amended Plan”).

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Stock options vest based upon the terms within the individual option grants, with an acceleration of the unvested portion of such options upon a change in control event, as defined in the Amended Plan. The options are not transferable except by will or domestic relations order. The option 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. The number of shares remaining available for future issuance under the Amended Plan as of December 31, 2023 and 2022 was 243,818 and 146,393, respectively.

In 2023, there were no option grants issued under the Plan.

In 2022, we granted nonqualified options to purchase an aggregate of 761,650 shares of common stock at $1.10 per share and $1.20 per share to certain officers and employees. These options have a vesting schedule offour years and expire inten years. The fair value of the options issued in 2023 was $321,910. The weighted-average grant date fair value of stock options granted during 2022 was $0.42 per share.

We adopted the 2022 Stock Incentive Plan (the "2022 Plan"), under which the Board of Directors may grant incentive or non-qualified stock options and stock grants to key 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.

Under the 2022 Plan, stock options vest based upon the terms within the individual option grants, with an acceleration of the unvested portion of such options upon a change in control event, as defined in the 2022 Plan. The options are not transferable except by will or domestic relations order. The option price per share under the 2022 Plan cannot be less than the fair market value of the underlying shares on the date of the grant.

During the year ended December 31, 2023, we granted nonqualified options under the 2022 Plan to purchase an aggregate of 575,000 shares of common stock at prices between $0.88 per share and $1.10 per share to certain directors, officers and employees These options have a vesting schedule of two or four years and expire in ten years. The fair value of the options issued in 2023 was $244,625. The weighted-average grant date fair value of stock options granted during 2023 was $0.43 per share.

During the year ended December 31, 2022, we granted nonqualified options under the 2022 Plan to purchase an aggregate of 275,000 shares of common stock at prices between $1.00 per share and $1.41 per share to certain directors. These options have a vesting schedule of four years and expire in ten years. The fair value of the options issued in 2022 was $145,600. The weighted-average grant date fair value of stock options granted during 2022 was $0.53 per share

The number of shares remaining available for future issuance under the 2022 Plan as of December 31, 2023 was 3,068,750.

In 2023 and 2022, there were no options exercised.

Stock option activity for the year ended December 31, 2023 was as follows:

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We used a forfeiture rate of 15% to calculate the expected to vest shares in the table above. We use the Black-Scholes option pricing model to determine the fair value of stock options granted. 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 of four 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 2023 and 2022 are as follows:

During the years ended December 31, 2023 and 2022, we recognized stock-based compensation expense of $250,394 and $334,149, respectively, related to the issuance of stock options. No tax benefit was recognized related to the stock-based compensation expense recorded during either of the years. At December 31, 2023 and 2022, the total compensation cost related to unvested stock option awards not yet recognized is $451,298 and $500,059, respectively. The unvested stock compensation at December 31, 2023 will be recognized over a weighted average period of 2.77 years.

Note 16. Fair Value Measurements

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.

Level 3 - Unobservable inputs reflecting management’s own assumptions about the input used in pricing the asset or liability.

The following table presents the asset reported in the consolidated balance sheet measured at its fair value on a recurring basis as of December 31, 2023 and 2022 by level within the fair value hierarchy:

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We utilize a Level 2 category fair value measurement to value our investment in EuroSite Power Inc. as an available-for-sale 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 are classifying as Level 2.

The following table summarizes changes in Level 2 assets which are comprised of marketable equity securities for the years ended December 31, 2023 and 2022:

The following table presents the liability reported in the consolidated balance sheet measured at its fair value on a recurring basis as of December 31, 2023 and 2022 by level within the fair value hierarchy:

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We utilize a Level 3 category fair value measurement to value the contingent consideration liability at period end since there are no quoted prices for this liabilities 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 consideration calculation requires management to make estimates and assumptions that affect the reported amount of the liability.The contingent 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.

Note 17. Retirement Plans

We have a defined contribution retirement plan (the “Plan”), which qualifies under Section 401(k) of the Internal Revenue Code (IRC). Under the Plan, employees meeting certain requirements may elect to contribute a percentage of their salary up to the maximum allowed by the IRC. We matched a variable amount based on participant contributions up to a maximum of 4.5% of each participant’s salary until May 2020 when we discontinued the matching of employee contributions for those employees not covered under a collective bargaining agreement. Effective July 1, 2023, we reinstituted the employer match based on participant contributions which are capped at a maximum of $250 per quarter and $1,000 per fiscal year. We contributed approximately $65,705 and $39,664 in matching contributions to the Plan in 2023 and 2022, respectively.

Note 18. Segments

As of December 31, 2023, we were organized into three operating segments through which senior management evaluates our business. These segments, as described in more detail in Note 1. "Nature of Business and Operations", are organized around the products and services provided to customers and represent our reportable segments. Prior to the acquisition of ADGE (see Note 4. "Acquisition of American DG Energy Inc."), our operations consisted of a single segment. The following table presents information by reportable segment for the years ended December 31, 2023 and 2022:

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Note 19. Income Taxes

A reconciliation of the federal statutory income tax provision to our actual provision for the years ended December 31, 2023 and 2022 is as follows:

The components of net deferred tax assets recognized in the accompanying consolidated balance sheets at December 31, 2023 and 2022 are as follows:

At December 31, 2023, we had approximately $38,710,000 of Federal net operating loss carryforwards ("NOL") of which $1,547,000 expired as of December 31, 2023, $22,393,000 expire beginning in 2024 through 2039 and $16,317,000 have an indefinite carryforward. In addition, we have $27,190,000 of state net operating losses, expiring at various dates starting in 2024 through 2042.

The Tax Cuts and Jobs Act was enacted on December 22, 2017. A significant provision of the act was to reduce the statutory Federal tax rate from 34% to 21%. During 2023, our valuation allowance increased by $1,314,000. This increase is

F- 23 affected by the absorption of deferred tax attributes associated with its acquisition of American DG Energy, Inc. along with permanent book to tax differences and provision to return adjustments.

In accordance with the provisions of the Income Taxes topic of the Codification, we have evaluated the positive and negative evidence bearing upon the realizability of our deferred tax assets, which are comprised principally of net operating losses. Management has determined that it is more likely than not that we will not recognize the benefits of federal and state deferred tax assets and, as a result, a full valuation allowance has been established for 2022 and 2023, respectively.

Utilization of the NOL and research and development credit carryforwards are subject to a substantial annual limitation due to ownership changes, as provided by Section 382 of the Internal Revenue Code of 1986, as well as similar state provisions. Ownership changes may limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period.

We acquired American DG Energy, Inc. during 2017, by acquiring 100 percent of the company's stock. Accordingly, utilization of their consolidated and/or separately computed NOL and/or tax credit carryforwards will be subject to an annual limitation under Internal Revenue Code Section 382. Any such limitation may result in expiration of a portion of the NOL or tax credit carryforwards before utilization. The extent of the limitation, and related allocation and impact upon the NOL and credit carryforwards has been determined to be $391,940 per year for a 20 year period at the ADGE level. However, we have sufficient pre-merger NOLs to offset anticipated taxable income for the taxable year ended December 31, 2023 and do not expected to be limited in NOL utilization for the period.

A full valuation allowance has been provided against our loss carryforwards and, if an adjustment is required under Section 382, it would be offset by a corresponding adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment were required.

We have not recorded any amounts for unrecognized tax benefits as of December 31, 2023 or 2022.

We file tax returns as prescribed by the tax laws of the jurisdiction in which we operate. In the normal course of business, we are subject to examination by federal and state jurisdictions, where applicable. There are currently no pending tax examinations. Our tax returns from tax year 2020 are still open for examination for both federal and state jurisdictions.

Note 20. Subsequent Events

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 for the period ended December 31, 2023.

On February 1, 2024, Tecogen and Aegis amended the March 15, 2023 agreement ("Agreement") with Aegis Energy Services, LLC (“Aegis”) to add eighteen (18) additional maintenance contracts (the "Amendment"). The Amendment 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. See Note 5."Aegis Contract and Related Asset Acquisition" of the Notes to the Consolidated Financial Statements.

On March 21, 2024, John H. Hatsopoulos amended the terms of the Promissory Note, dated October 10, 2023, extending the maturity date by one year, making the maturity date October 10, 2025 and agreeing to accept payment in cash or Tecogen Inc. common stock.

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