Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer”, “accelerated filer”, “smaller reporting company” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

This report also contains or may contain market data related to our business and industry and any such market data may include projections that are based on certain assumptions. If these assumptions turn out to be incorrect, actual results may differ from the projections based on these assumptions. As a result, our markets may not grow at the rates projected by this data, or at all. The failure of these markets to grow at these projected rates may have a material adverse effect on our business, results of operations, financial condition, and the market price of our common stock.

Recent Developments

On April 17, 2020,March 15, 2023, we obtainedentered into an unsecured loan in the principal amount of $1,874,200 from Webster Bank, NAagreement ("Webster"Agreement") under the Paycheck Protection Program adoptedwith Aegis Energy Services, LLC (“Aegis”) pursuant to the Coronavirus Aid, Reliefwhich Aegis agreed to assign to us and Economic Recovery Act, as amended ("CARES Act"we agreed to assume certain Aegis maintenance agreements, we agreed to purchase certain assets, and related matters (“Acquisition”). The loan was forgivable ifOn April 1, 2023, the proceeds were utilizedAcquisition 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 for approximately 200 cogeneration systems, and acquired certain vehicles and inventory used by usAegis in connection with the performance of such maintenance services, and, following closing hired eight (8) Aegis employees to provide services with respect to such maintenance agreements. At closing, we acquired eight (8) Aegis vehicles for payroll, utilities, and rent expenses. On January 19, 2021consideration consisting of $170,000 in cash. Also, we received confirmationissued credits against outstanding accounts receivable due from Webster that the Paycheck Protection Program Loan in the original principal amount of $1,874,200 together with accrued interest of $13,659 was forgiven in full effective as of January 11, 2021. The loan forgiveness of $1,887,859 was accounted for as a debt extinguishment and is reported as a separate component of other income (expense), net in our condensed consolidated statement of operations.

On December 14, 2018,July 20, 2022, we enteredannounced our intention to focus on opportunities for low carbon Controlled Environment Agriculture ("CEA"). We believe that CEA offers an exciting opportunity to apply our expertise in clean cooling, power generation, and greenhouse gas reduction to address critical issues affecting food and energy security. We propose to address this challenge by developing a highly efficient energy solution for CEA grown produce using our cogeneration products in conjunction with solar energy generation, energy storage, and other technologies.

In recent years our cogeneration equipment has been used in numerous cannabis cultivation facilities because our systems significantly reduce operating costs, reduce the facility GHG footprint and offer resiliency to grid outages. Our experience providing clean energy solutions to cannabis cultivation facilities has given us significant insight into agreementsrequirements relating to the sale of two energy purchase agreements and related energy production systemsenergy-intensive indoor agriculture applications that we expect to be transferable to CEA facilities for $2 million and on March 5, 2019 entered into agreements relating to the sale of six energy purchase agreements and related energy production systems for $5 million. In connection with these sales, we entered into agreements to provide billing and asset management services and operations and maintenance services for agreed fees for the durationfood production.

Impact of the Russian Invasion of Ukraine

Presently, we have no operations or customers in Russia or the Ukraine. The higher energy purchase agreements, pursuant to which we guarantee certain minimum collections and are entitled to receive fifty percent of the excess of collections over agreed minimum thresholds. In October 2021 the minimum guarantee with respect to one of the energy purchase agreements was modified by reducing the guaranteed minimum collections by $35,000 per year, the guaranteed minimum collection amount associated with one site that was sold by the customer.

Overview of Our Business

Our products offer customers energy savings, resiliency and a cleaner environmental footprint. Our cogeneration, chiller and heat pump systems use an engine to generate electricity or shaft work and recover the waste heat from the engine. Our systems are greater than 88% efficient compared to typical electrical grid efficiencies of 40% to 50%. As a result, our greenhouse gas (GHG) emissions are typically half that of the electrical grid. Our systems generate electricity and hot water or in the case of our Tecochill product, both chilled water and hot water. Our products are expected to run on Renewable Natural Gas (RNG) as it is introduced into the US gas pipeline infrastructure.

Our natural gas-powered cogeneration systems (also known as combined heat and power or “CHP”) are efficient because they drive electric generators or compressors, which reduce the amount of electricity purchased from the utility while recovering the engine’s waste heat for water heating, space heating, and/or air conditioning at the customer’s building.

Traditional customers for our InVerde and Tecopower products have a simultaneous need for electrical power and hot water. These include hospitals, nursing homes, schools, universities, health clubs, spas, hotels and motels, office and multi-unit residential buildings. Conversely our Tecochill product benefits customers who have a simultaneous need for cooling and hot water which is typical in sites such as hospitals, ice rinks, indoor agriculture and food processing. Our Tecofrost refrigeration compressors are applied primarily to industrial applications that include cold storage, wineries, dairies, ice rinks and food processing. Market drivers include the price of natural gas, local electricity rates, environmental regulations, and governmental energy policies, as well as customers’ desire to become more environmentally responsible.

Our cooling and refrigeration products provide both cooling and make use of high grade waste heat. This is of particular advantage in facilities that control both temperature and humidity. In such facilities, climate control is achieved by cooling the facility to remove humidity and then reheating to the required temperature. Using engine waste heat to perform the reheat while utilizing natural gas to generate the cooling provides significant economic and environmental benefits. As a result our product has significant competitive advantages in applications that operate year round such as controlled environment agriculture, indoor ice rinks, and hospitals.

Through our factory service centers in California, Connecticut, Florida, Massachusetts, Michigan, New Jersey, New York, and Toronto, Canada,Ontario, our specialized technical staff maintains our products via long-term service contracts. To date we have shipped over 3,0003,200 units, some of which have been operating for almost 35 years. We established a service center in Toronto, Canada in August 2020 to support our existing population of chillers and cogeneration units including 26 cogeneration units sold in this territory during 2020 to serve public housing facilities.

Our operations are comprised of three business segments. Our Products segment designs, manufactures and sells industrial and commercial cogeneration systems as described above. Our Services segment provides O&M services for our products under long term service contracts. Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements.

In 2017, a group of generators owned by a single customer in Southern California were supplied Ultera kits because of their particular requirement to exceed the 200-hour annual limit. These units are now operational and have been tested by the customer and shown to be compliant with the local pollution limits which we believe to be the strictest anywhere in the United States, and potentially the world. Our CHP products have been permitted to this same standard. However, CHP products are

It is noteworthy that these engine-generators have been used in California to power dispersed loads in a fire-prone area where frequent de-energizing of the electric overhead power lines is required for safety. We believe this application to be a new and significant application for the Ultera technology in light of the widely publicized widespread outages in California which have occurred in 2019 and 2020.

Our Energy Production segment sells energy in the form of electricity, heat, hot water and cooling to our customers under long-term sales agreements which represented 7.1% and 6.5%7.0% of our consolidated revenues for the years ended December 31, 20212023 and 2020, respectively.2022. See Note 1718. "Segments" of the Notes to the Consolidated Financial Statements.    

A number of developments related primarily to the deregulation of the utility industry as well as significant technological advances have now broadened the range of power supply choices available to all types of customers. Cogeneration, which harnesses waste energy from power generation processes and puts it to work for other uses on-site, can boost the energy conversion efficiency to nearly 90%, a better than two-fold improvement over the average efficiency of a fossil fuel plant. This distributed generation, or power generated on-site at the point of consumption rather than power generated centrally, eliminates the cost, complexity, and inefficiency associated with electric transmission and distribution. The implications of the CHP distributed generation approach are significant. We believe that if cogeneration were applied on a large scale, global fuel usage might be dramatically curtailed and the utility grid made far more resilient. Furthermore, with

OurWe estimate that our products can often reduce the customer’s operating costs (for the portion of the facility loads to which they are applied) by approximately 30% to 60% based on our estimates,, which provides an excellent rate of return on the equipment’s capital cost in many areas of the country with high electricity rates. Our chillers are especially suited to regions where utilities impose extra charges during times of peak usage, commonly called “demand” charges. In these cases, the gas-fueled chiller reduces the use of electricity during the summer, the costliest time of year.

Decentralizing power generation or reducing energy requirements at a customer's site not only relieves the capacity burden on existing power plants, but also lessens the burden on transmission and distribution lines. This ultimately improves the grid’s reliability and reduces the need for costly upgrades.

Increasingly favorable economic conditions may improve our business prospects domestically and abroad. Specifically, we believe that natural gas prices are expected to increase from their current values, and that electric rates are expected to continue to rise more significantly over the long-term as utilities pay for grid expansion, better emission controls, efficiency improvements, and the integration of renewable power sources.

Most potential new customers in the U.S. require less than 1 MW of electric power and less than 1,200 tons of cooling capacity. We are targeting customers in states with high electricity rates in the commercial sector, such as California, Connecticut, Massachusetts, New Hampshire, New Jersey, and New York. Most of these states also have high peak demand rates, which favor utilization of our modular units in groups so as to assure redundancy and peak demand savings. Governmental agencies in some of these regions may also provide generous rebates that can improve the economic viability of our systems.

We aggressively market to potential customers where utility pricing aligns with our advantages. These areas include regions that have strict emissions regulations, such as California, or those that reward CHP systems that are especially non-polluting, such as New Jersey. Currently, more than 23 states recognize CHP as part of their Renewable Portfolio Standards or Energy Efficiency Resource Standards.

The traditional markets for CHP systems are buildings with long hours of operation and with corresponding demand for electricity or cooling and heat. Traditional customers for our cogeneration systems include controlled environment agriculture, hospitals, nursing homes, colleges, universities, health clubs, spas, hotels, motels, office and retail buildings, food and beverage processors, multi-unit residential buildings, laundries, ice rinks, swimming pools, factories, municipal buildings, and military installations.

Traditional customers for our chillers, refrigeration compressors and heat pumps overlap with those for our cogeneration systems. Engine-driven chillers are often used as replacements for aging electric chillers because they both occupy similar amounts of floor space and require similar maintenance schedules. This is also the case with refrigeration compressors.

The markets for our products are highly competitive, though we believe that we offer customers a suite of premier best-in-class clean energy and thermal solutions.

InVerde and Tecopower

Our combined heat and power products that produce electricity and hot water compete with the utility grid, existing technologies such as other reciprocating engine and microturbine CHP systems, and other emerging distributed generation technologies including solar power, wind-powered systems, and fuel cells. Our products are highly competitive between 60KW and 1.5MW in electrical generation capacity. In this size range we have other reciprocating engine competitors, although we have strong competitive advantages when it comes to ease of utility interconnection, ease of installation in tight spaces and our microgrid capabilities. We believe that Capstone Turbine Corporation is the only microturbine manufacturer with a commercial presence in CHP.

Although operating solar and wind powered systems produce no emissions, the main drawbacks to these renewable powered systems are their dependence on weather conditions, their reliance on backup utility grid-provided power, and high capital costs that can often make these systems uneconomical without government subsidies. Similarly, while the market for fuel cells is still developing, a number of fuel cell companies are focused on markets similar to ours. Fuel cells, like solar and wind powered systems, have received higher levels of incentives for the same type of applications as CHP systems in many territories. We believe that, notwithstanding these higher government incentives, our CHP solutions provide a better value and more robust solution to end users in most applications.

Additionally, our patents relating to the Ultera ultra-low emissions technology give our products a strong competitive advantage in markets where severe emissions limits are imposed or where very clean power is favored, such as New Jersey, California, and Massachusetts.

Overall, we compete with end users’ other options for electrical power, heating, and cooling on the basis of our technology’s ability to:

Similarly, in the growing Microgrid segment, neither fuel cells nor microturbines can respond to changing energy loads when the system is disconnected from the utility grid. Engines such as those used in our equipment inherently have a fast-dynamic response to step load changes, which is why they are the primary choice for emergency generators. Fuel cells and microturbines require additional energy storage systems to be utilized for time-limited off-grid operation, giving our engine-driven solutions an advantage for Microgrid and resiliency applications.

Our Tecochill line of chillers are the only gas-engine-driven chillers available on the market. Natural gas can also fuel absorption chillers, which use fluids to transfer heat without an engine drive. However, engine driven chillers continue to have an efficiency advantage over absorption machines. Tecochill chillers reach efficiencies well above levels achieved by similarly sized absorption systems. Low natural gas prices in the United States improve the economics of natural gas-fueled chillers while their minimal electric demand on backup power systems make them ideal for facilities requiring critical precision climate control. In 20222023 we plan to expandexpanded our Tecochill range of products to includewith the introduction of a hybrid air cooled chiller based on the inverter design used in the InVerde. The hybridhybrid-drive air-cooled chiller will take simultaneous inputs from the electrical grid

Our long and rich research and development tradition and sustained programs have allowed us to cultivate deep engineering expertise. We have strong core technical knowledge that is critical to product support and continuous product improvement efforts. Our TecoDrive engine, permanent magnet generator, cogeneration and chiller products, InVerde, Ilios heat pumps, and most recently the Ultera emissions control system, and our hybrid-drive air-cooled chiller were all created and optimized in-house with both public and private funding support.support from third-parties.

We continue to seek alliances with utilities, government agencies, universities, research facilities, and manufacturers. We have succeeded in developing new technologies and products in collaboration with several entities, including:

We also continue to leverage our resources with government and industry funding, which has yielded a number of successful developments, including the Ultera low-emissions technology, sponsored by the California Energy Commission and Southern California Gas Company. Pursuant to the terms of the grants from the California Energy Commission, the California Energy Commission has a royalty-free, perpetual, non-exclusive license to these technologies for government purposes.

Our current internal R&D efforts are focused on the hybrid air cooledhybrid-drive air-cooled chiller that utilizes the basic inverter design used in the InVerde e+. Management believes that this chiller will address a significant market segment that is currently unaddressednot addressed by our existing Tecochill product. For the years ended December 31, 20212023 and 2020,2022, we spent $542,079$840,011 and $767,323,$732,873, respectively, on research and development activities.

In addition, we have licensed specific rights to Microgrid software algorithms developed by University of Wisconsin researchers for which we pay royalties to the assignee, The Wisconsin Alumni Research Foundation (WARF). The specific patent named in our agreement isPursuant to U.S. Patent 7,116,010, titled “Control of small distributed energy resources” (7,116,010), granted in 2006.2006 and expires on March 27, 2024. Our exclusive rights are for engine-driven systems utilizing natural gas or diesel fuel in the application of power generation where the per-unit output is less than 500 kW. The software allows our products to be integrated as a Microgrid, where multiple InVerde units can be seamlessly isolated from the main utility grid in the event of an outage and re-connected to it afterward. The licensed software allows us to implement such a Microgrid with minimal control devices and associated complexity and cost. We consider the Microgrid software algorithm licensed from WARF to be a key feature of our InVerde product, and one that would be difficult to duplicate outside the patent. We pay WARF a royalty for each cogeneration module sold using the licensed technology. Such royalty payments have been in the range of $5,000 to $13,000$15,000 on an annual basis through the year ended December 31, 2021.2023. In addition, WARF reserved the right to grant non-profit research institutions and governmental agencies non-exclusive licenses to practice and use, for non-commercial research purposes, the technology developed by us that is based on the licensed software.

We consider our patents and licensed intellectual property to be important in the operation of our business. The expiration, termination, or invalidity of one or more of these patents may have a material adverse effect on our business.

One other company has developed a product that seeks to compete with our inverter-based InVerde, although it does not offer all of the same benefits and features offered by our InVerde products. We anticipate that an inverter-based product with at least some of the features offered by our InVerde products will be introduced by others, but we believe that our competitors will face serious challenges in duplicating the InVerde. Product development time and costs would likely be significant, and we expect that our patent for the inverter-based CHP system, (7,239,034)U.S. Patent 7,239,034, provides significant protections for key features. We consider the Microgrid software algorithm licensed from WARF to be a key feature of our InVerde product, and one that would be difficult to duplicate outside the patent.

In 2013, we purchased rights to designs and technologies,technology, including patents granted or pending for our permanent magnet generators. A key component of our InVerde module uses this acquired technology.

Our patents for the Ultera low-emissions control technology applies to all our gas engine-driven products and may have applications to other rich-burn spark-ignited internal combustion engines. We have been granted patents for this technology in Europe, Australia, Brazil, Canada, Japan, Mexico, Korea and Singapore.

Copyrights

Our control software is protected by copyright laws or through an exclusive license agreement.

Trademarks

We have registered the brand names of our equipment and logos used on our equipment. These registered and pending trademarks include Tecogen, Tecochill, Tecopower, Ultera, InVerde, Ilios, InVerde e+ and the associated logos. We will continue to trademark our product names and symbols.

We rely on treatment of our technology as trade secrets through confidentiality agreements, which our employees and vendors are required to sign. Also, we rely on non-disclosure agreements with others that have or may have access to confidential information to protect our trade secrets and proprietary knowledge.

We are focused on continuously strengthening our manufacturing processes and increasing operational efficiencies. Many of the components used in the manufacture of our highly-efficient clean energy equipment are readily fabricated from commonly available raw materials or are standard available parts sourced from multiple suppliers. We believe that adequate supplies exist to meet our near to medium term manufacturing needs. We have an on-going focus on developing and implementing new systems to simplify our manufacturing processes, product sourcing methods, and our supply chain.

We have a combined total of approximately 27,000 square feet of manufacturing and warehouse space running on a single 5-day per week shift at our Waltham, Massachusetts facility. We believe we have sufficient spare capacity to meet near to medium term demand without incurring additional fixed costs althoughcosts. The lease for our headquarters located in Waltham, leaseMassachusetts was extended on March 1, 2024 and expires on April 30, 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. We have a total of approximately 21,000 square feet of manufacturing and warehouse space at the Billerica, Massachusetts facility. The lease agreements which commenced on January 1, 2024, and we will needprovide for initial lease terms of five (5) years, expiring on December 31, 2028, with two successive options to identify and move to alternate space prior to expirationrenew for additional terms of the Waltham lease.five (5) years.

Several kinds of federal, state and local government regulations affect our products and services, including but not exclusive to:

Our markets can be positively or negatively impacted by the effects of governmental and regulatory matters. We are impacted not only by energy policy, laws, regulations and incentives of governments in the markets in which we sell, but also by rules, regulations and costs imposed by utilities. Utility companies or governmental entities may place barriers on the installation or interconnection of our products with the electric grid. Further, utility companies may charge additional fees to customers who install on-site power generation to reduce the electricity they take from the utility and to preserve electric capacity available from the grid for back-up or standby purposes. These types of restrictions, fees or charges could hamper the ability to install or effectively use our product or increase the cost to our potential customers for using our systems. This could make our systems less desirable, adversely impacting our revenue and profitability. In addition, utility rate reductions can make our products less competitive, causing a material adverse effect on our operations. These costs, incentives and rules are not always the same as those faced by technologies with which we compete.

Similarly, rules, regulations, laws and incentives could also provide an advantage to our distributed generation solutions as compared with competing technologies if we are able to achieve requiredbecause they enable compliance in a lower cost, more efficient manner. Additionally,manner with reduced emissions and higher fuel efficiency could helpwhich helps our customers combat the effects of global warming. Accordingly, weWe may benefit from increased government regulations that impose tighter emission and fuel

Our products are well-suited to meet the needs of the rapidly emerging indoor agriculture market, including cannabis.cannabis and other high volume leafy greens. To date our focus in the indoor agricultural market has primarily involved cannabis, a product with high revenue generating potential. However, we have sold to other indoor agricultural growers, and we believe that the indoor food production market will provide significant opportunities for us. The indoor agriculture market in particular has the potential to be a major driver of growth as states move to legalize the use of cannabis for medicinal purposes and recreational use. However, under the Controlled Substances Act (CSA) cannabis continues to be categorized as a Schedule I drug, so that cannabis growers continue to face significant uncertainty regarding their ability to conduct business.

First passed by Congress in 2014, the Rohrabcher-FarrRohracher-Farr Amendment is an amendment to the annual appropriations bill that, among other things, funds the Department of Justice. It prohibits the US Attorney General from using funds to prosecute the medical use of cannabis. It does not address recreational use. On January 4, 2018, US Attorney General Jeff Sessions rescinded the Cole memo. Written in 2013, the Cole memo had directed US Attorneys not to allocate resources to prosecute "individuals whose actions are in clear and unambiguous compliance with existing state laws" regarding the cannabis market. As of the date of the filing of this report, we are not aware of any US Attorney who has taken action against participants in the recreational cannabis market operating in accordance with state law. The uncertainty we face regarding the potential for growth from the sales to the cannabis industry is due in part to uncertainty regarding prosecutorial priorities of the current Presidential administration.administration as well as the ability of cannabis growers to obtain funding in an environment where national bankers are not permitted to fund cannabis growth facilities.

Our Energy Production segment is subject to extensive government regulation. We are required to file for local construction permits (electrical, mechanical and the like) and utility interconnects, and are required to make various local and state filings related to environmental emissions.

In the past, many electric utility companies have raised opposition to distributed generation of energy, a critical element of our business model. Such resistance has generally taken the form of stringent standards for interconnection and the use of target rate structures as disincentives to combined generation of on-site power and heating or cooling services. A distributed generation facility's ability to obtain reliable and affordable back-up power through interconnection with the grid is essential to our business model. Utility policies and regulations in most states often do not accommodate widespread on-site generation. Barriers erected by electric utility companies and unfavorable regulations, where applicable, make our ability to connect to the electric grid at customer sites more difficult or uneconomic and is an impediment to the growth of our business. The development of our business could be adversely affected by any slowdown or reversal in the utility deregulation process or by difficulties in negotiating back-up power supply agreements with electric providers in the areas where we seek to do business.

Environmental Matters

We are regulated by federal, state and international environmental laws governing our use, transport and disposal of substances and control of emissions. In addition to governing our manufacturing and service operations, these laws often impact the development of our products, including, but not limited to, required compliance with air emissions standards applicable to internal combustion engines. We have made, and will continue to make, the necessary research and development and capital expenditures to comply with these emissions standards.

We believe our success in delivering energy efficient, ultra clean cogeneration systems, chillers and energy production services relies on our culture, values, and the creativity and commitment of our people. We strive to maintain healthy, safe, and secure working conditions and a workplace where our employees are treated with respect and dignity. Our vision is to create an inclusive, diverse and authentic community that inspires collaboration, integrity, engagement, and innovation. We are striving to create a world-class employee experience – one that offers opportunity for personal and professional growth, and enables work-life balance that aligns with our core values.

Employee Health and Safety

We understand the benefits of employee health and safety and continue to invest in programs, products, and resources. We also understand the environment of trust and fairness that exists when information is openly shared. We also continue to invest in products and services to meet the health and safety needs of our customers and communities.

Talent Acquisition and Development

Our values are integral to our employment process and serve as guideposts for leadership. The ultimate goal is straightforward: find great people, ask them to join, and give them a reason to stay. Reasons include fair compensation, a complete array of employee benefits to include: health, dental and life insurance; short-term and long-term disability insurance; HSA account funding; generous time off benefits; and the grant of options or awards to purchase shares of our common stock. Recently we instituted web-based training for all of our employees.

As of December 31, 2021,2023, we employed 7792 full-time employees and 21 part-time employees,employee, including 74 sales and marketing personnel, 4663 service personnel, 1917 manufacturing personnel and 79 finance and administrative personnel. Nine of our New Jersey service employees are represented by a collective bargaining agreement which expires on December 31, 20222025 and thereafter renews annually unless terminated by either party by written notice within sixty days prior to the expiration date.

Our internet website address is http://www.tecogen.com. Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other reports and filings with the SEC are available free of charge on our website as soon as reasonably practicable after the reports are filed with, or furnished to, the SEC. Information contained on our website is not incorporated into this Annual Report on Form 10-K or our other securities filings with the SEC. The SEC maintains an internet website at www.sec.gov which contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC.

Our financial condition and results ofWe may need to raise additional financing if cash generated from our operations have been and may be materially adversely affected by the recent 2019 novel Coronavirus (COVID-19) outbreak.is insufficient.

The outbreak of the 2019 novel coronavirus has developed into a global pandemic that has and could continue to have a material and adverse effect on our business, financial condition and results of operations. During the year ended December 31, 2021,2023, our revenues werecontinued to be negatively impacted due to supply chain issues and project deferrals. The extent to which the coronavirus will continue to impact our business and our financial results will depend on future developments, which are highly uncertain and cannot be predicted. As part of our pandemic response plan, our sales, engineering, and select administrative functions may be operated remotely when necessary or appropriate while our manufacturing and service teams continues to function normally, subject to customer-initiated disruptions in service.

If the cash generated by operations together with proceeds of funds available under our related party loans under the CARES Act, as amended ("CARES Act") that we have obtainedwith John N. Hastopoulos, a director and were forgiven as described belowprincipal shareholder and Earl R. Lewis, III, a director, are insufficient to fund our future operating requirements, we will need to raise additional funds through public or private equity or debt financings. Such financing may not be available to us when needed, or if available, may not be available on terms that are favorable to us and could result in significant dilution to the holdings of our stockholders. Furthermore, any such debt financing is likely to include financial and other covenants that may impede our ability to react to changes in the economy or industry.

Based upon our operating and cash flow plan, and the proceeds of our Paycheck Protection Loans, we believe existing resources, including cash and cash flows from operations will be sufficient to meet our working capital needs for the next twelve months. If adequate financing is not available when needed, we may be required to implement cost-cutting strategies, delay production, curtail research and development efforts, or implement other measures, which may adversely affect our overall results of operations and financial condition and the price of our stock.

If we experience a period of significant growth or expansion, it could place a substantial strain on our resources.

If our cogeneration and chiller products penetrate the market rapidly, we may be unable to deliver large volumes of technically complex products or components to our customers on a timely basis and at a reasonable cost to us. We have never ramped up our manufacturing capabilities to meet significant large-scale production requirements. If we were to commit to deliver large volumes of products, we may not be able to satisfy these commitments on a timely and cost-effective basis.

Our operating history is characterized by losses and there can be no assurance we will be able to increase our sales and sustain profitability in the future.

Although we made a net profit of $3.7 million in 2021 as a result of the Paycheck Protection Program Loans and Employee Retention Credits in the amount of $5.0 million in the aggregate, weWe have historically incurred annual operatingnet losses, including an operatinga net loss of $1.2 million for 2021, an operating loss of $6.0 million for 2020, and an operating loss of $4.7 million for 2019.$4,598,108 in 2023. Our business is capital intensive and, because our products generally are built to order with customized

We are dependent on a limited number of third-party suppliers for the supply of key components for our products.

We use third-party suppliers for components in all of our products. Our engine supplier, generator supplier forengines and generators required in our cogeneration products (other than the InVerde), and the compressor and vessel sets in our chillers, are all purchased from large multinational equipment manufacturers. The loss of one or more of our suppliers could materially and adversely affect our business if we are unable to replace them. While alternate suppliers for the manufacture of our engine, generators and compressors have been identified, should the need arise, there can be no assurance that alternate suppliers will be available and able to provide such items on acceptable terms or on a timely basis.

From time to time, shipments of components for our products can be delayed because of industry-wide or other shortages of necessary materials and components from third-party suppliers, as well as shipping delays at points of importation. A supplier's failure to supply components in a timely manner, or to supply components that meet our quality, quantity, or cost requirements, or our inability to obtain substitute sources of these components on a timely basis or on terms acceptable to us, could impair our ability to deliver our products in accordance with contractual obligations.

The amount of our backlog is subject to fluctuation due to our customers’ experiencing unexpected delays in financing, permitting or modifications in specifications of the equipment.

Our total product and installation backlog as of December 31, 20212023 was $11,321,043$7,388,145 compared to $8,273,879$6,722,138 as of December 31, 2020.2022. Although we expect our customers to issue definitive purchase orders with respect to such backlog, there can be no assurance that such amounts will not be subject to modification in the event customers experience unexpected delays in obtaining permits, interconnection agreements or financing. As a consequence of COVID-19, weWe have experienced order delays and deferrals for our products due to business closures or the inability to obtain government issued permits to conduct product installations. Any of such events may result in customers modifying the equipment or the terms or timing of the expected installation, which may result in changes to the amount of backlog attributed to those projects.

We experience significant fluctuations in revenues from quarter to quarter on our product sales which may make period to period comparisons difficult.

We have low volume, high dollar sales for projects that are generally non-recurring, and therefore our sales have fluctuated significantly from period to period. Fluctuations cannot be predicted because they are affected by the purchasing decisions and timing requirements of our customers, which are unpredictable. Such fluctuations may make quarter to quarter and year to year comparisons difficult.

We expect significant competition for our products and services.

Many of our competitors and potential competitors are well established and have substantially greater financial, research and development, technical, manufacturing and marketing resources than we do. If these larger competitors decide to focus on the development of distributed power or cogeneration, they have the manufacturing, marketing and sales capabilities to complete research, development, and commercialization of these products more quickly and effectively than we can. There can also be no assurance that current and future competitors will not develop new or enhanced technologies or more cost-effective systems, and therefore, there can be no assurance that we will be successful in this competitive environment.

We may not achieve production cost reductions necessary to competitively price our products, which would adversely affect our sales.

We believe that we will need to reduce the unit production cost of our products over time to maintain our ability to offer competitively priced products. Our ability to achieve cost reductions will depend on our ability to develop low-cost design enhancements, to obtain necessary tooling and favorable supplier contracts, and to increase sales volumes so we can achieve economies of scale. We can make no assurance that we will be able to achieve any such production cost reductions. Our failure to do so could have a material adverse effect on our business and results of operations.

Our products involve a lengthy sales cycle and we may not anticipate sales levels appropriately, which could impair our results of operations.

The sale of our products typically involves a significant commitment of capital by customers, with the attendant delays frequently associated with large capital expenditures. For these and other reasons, the sales cycle associated with our products is typically lengthy and subject to a number of significant risks over which we have little or no control. We expect to plan our production and inventory levels based on internal forecasts of customer demand, which is highly unpredictable and can fluctuate substantially. If sales in any period fall significantly below anticipated levels, our financial condition, results of operations and cash flow would suffer. If demand in any period increases well above anticipated levels, we may have difficulties in responding, incur greater costs to respond, or be unable to fulfill the demand in sufficient time to retain the order,

The economic viability of our projects depends on the price spread between natural gas and other fuel and electricity, and the variability of these prices creates a risk that our projects will not be economically viable and that potential customers will avoid such energy price risks.

The economic viability of our CHP products depends on the spread between natural gas fuel and electricity prices. Volatility in one component of the spread, such as the cost of natural gas and other fuels (e.g., propane or distillate oil), can be managed to some extent by means of futures contracts. However, the regional rates charged for both base load and peak electricity may decline periodically due to excess generating capacity or general economic recessions, and both the cost of natural gas and the cost of electricity for base load and peak load may be adversely affected by geopolitical disruptions such as Russian expansion into the Ukraine and political and other responses to such expansionist activity.

Our products and on-site utility service could become less competitive if electric rates were to fall substantially in the future, although, historically, electric rates have not had any sustained decline in price. Potential customers may perceive the risk of unpredictable swings in natural gas and electricity prices as a risk of investing in on-site CHP, and may decide not to purchase CHP products.

We may make acquisitions or take other corporate strategic actions that could harm our financial performance.

To expedite development of our business, including with regard to equipment installation and service functions, we anticipate investigating and potentially pursuing future acquisitions of complementary businesses. Risks associated with such acquisitions include the diversion of management attention and cash from operations to cover the costs associated with acquisitions, disruption of our existing operations, loss of key personnel in the acquired companies, dilution through the issuance of additional securities, assumptions of existing liabilities, and commitment to further increase operating expenses. If any or all of these problems actually occur, acquisitions could negatively impact our financial performance and future stock valuevalue.

Expiring customer contracts may lead to decreases in revenue and increases in expenses.

Each year, a portion of our customer contracts expire and need to be renewed or replaced. We may not be able to renew or extend contracts with existing customers or obtain replacement contracts at attractive rates or for the same term as the expiring contracts. To the extent we are unable to extend customer contracts prior to their expiration date,dates, energy production revenue will decline due to less energy billing. Expiring customer contracts can also lead to an increase in expenses because we are obligated to remove the equipment from the customer location at our own expense at the end of the customer contract. The investment required to obtain replacement contracts, including the manufacture and installation of the cogeneration or chiller equipment and the costs to incorporate this equipment into a facility are significant. To the extent that we do not have sufficient liquidity, may have an adverse impact on our ability to add new contracts with energy production sites.sites may be adversely impacted.    

Our revenue from energy billing may be adversely impacted by increases in the price of natural gas, reductions in utility rates for electrical power, weather conditions, or by an increase in remote work and study environments, all of which could reduce our revenue.

Over the past several years there has been a sharp decreaseelectric rates have fluctuated, in electricsome instances rates have decreased, subsequent to the vast majority of customer contract dates, causing the billable value of the electrical power generated by our systems to decrease which has an adverse effect on our results of operations. In warmer months the customers do not use as much thermal energy because they do not have as much demand for heat at their locations. Due to lower demand in warmer months, we may not be able to bill for thermal energy and in turn may have a decrease in revenue. In addition, increases in the cost of natural gas may increase the cost of power generation in comparison to the cost of power from the electric grid and may result in decreased revenue and adversely affect our results of operation. Increased remote work

The growing political and remote study environments duringscientific sentiment is that global weather patterns are being influenced by increased levels of greenhouse gases in the COVID-19 pandemic has resultedearth’s atmosphere. This growing sentiment and the concern over climate change have led to legislative and regulatory initiatives aimed at reducing greenhouse gas emissions which warm the earth’s atmosphere. These warmer weather conditions could result in decreased commercial electricity and revenue generateda decrease in demand for our products in general. Moreover, proposals that would impose mandatory requirements on greenhouse gas emissions continue to be considered by policy makers in the United States. Laws enacted that could impact demand for the products we sell could adversely affect our systems, and has adversely affected ourbusiness, financial condition, results of operations.operations and cash flows. Significant increases in federal, state or municipal restrictions on emissions of carbon dioxide that may be imposed on gas-driven cogeneration and chillers could adversely affect demand for our product. Our inability to respond to such changes could adversely impact the demand for our products and our business, financial condition, results of operations or cash flows.

Our financial condition and results of operations could suffer if there is an impairment of goodwill or intangible assets.

As of December 31, 2021,2023, our goodwill was $2,406,156,$2,743,424, and our intangible assets were $1,181,023.$2,436,230. We recognizedperformed a goodwill impairment test at December 31, 2023 and determined that the estimated fair value of the energy production business assets and the Aegis maintenance service contracts, based on a discounted cash flow analysis, exceeded the carrying value of the assets and did not recognize goodwill impairment relating to our energy production segment of $2,875,711or service segment for the year ended December 31, 2020.2023. We are required to test intangible assets with indefinite lives, including goodwill, annually or, in certain instances, more frequently, and may be required to record impairment charges, which would reduce any earnings or increase any loss for the period in which the impairment was determined to have occurred. Our goodwill impairment analysis is sensitive to changes in key assumptions used in our analysis. If the assumptions used in our analysis are not realized, it is possible that an impairment charge may need

If we are unable to maintain our technological expertise in design and manufacturing processes, we will not be able to successfully compete.

We believe that our future success will depend upon our ability to continue to develop and provide innovative products and product enhancements that meet the increasingly sophisticated needs of our customers. However, this requires that we successfully anticipate and respond to technological changes in design and manufacturing processes in a cost-effective and timely manner. The development of new, technologically advanced products and enhancements is a complex and uncertain process requiring high levels of innovation, as well as the accurate anticipation of technological and market trends. There can be no assurance that we will successfully identify new product opportunities, develop and bring new or enhanced products to market in a timely manner, successfully lower costs, and achieve market acceptance of our products, or that products and technologies developed by others will not render our products or technologies obsolete or noncompetitive. 

The introduction of products embodying new technologies and the shifting of customer demands or changing industry standards could render our existing products obsolete and unmarketable. We may experience delays in releasing new products and product enhancements in the future. Material delays in introducing new products or product enhancements may cause customers to forego purchases of our products and purchase those of our competitors.

Our business is subject to product liability and warranty claims.

Our business exposes us to potential product liability claims, which are inherent in the manufacturing, marketing and sale of our products, and we may face substantial liability for damages resulting from the faulty design of products, manufacture of products or improper use of products by end users. We currently maintain product liability insurance, but there can be no assurance that this insurance will provide sufficient coverage in the event of a claim. Also, we cannot predict whether we will be able to maintain such coverage on acceptable terms, if at all, or that a product liability claim would not harm our business or financial condition. In addition, negative publicity in connection with the faulty design or manufacture of our products would adversely affect our ability to market and sell our products.

We sell our products with limited warranties. There can be no assurance that the provision in our financial statements for estimated product warranty expense will be sufficient. We cannot ensureThere can be no assurance that our efforts to reduce our risk through warranty disclaimers will effectively limit our liability. Any significant occurrence of warranty expense in excess of estimates could have a material adverse effect on our operating results, financial condition and cash flow. Further, we have at times

Turnkey construction contracts to which we are a party may contain liquidated damages provisions resulting from failure to achieve agreed milestones relating to construction activity. Agreements relating to the sale of equipment or energy may include performance and other obligations that may result in payment obligations to customers.

Utilities or governmental entities could hinder our entry into and growth in the marketplace, and we may not be able to effectively sell our products.

Utilities or governmental entities on occasion have placed barriers to the installation of our products or their interconnection with the electric grid, and they may continue to do so. Utilities may charge additional fees to customers who install on-site CHP and rely on the grid for back-up power. These types of restrictions, fees, or charges could make it harder for customers to install our products or use them effectively, as well as increase costs to potential customers. This could make our systems less desirable, thereby adversely affecting our revenue and other operating results.

The reduction, elimination or expiration of government and economic incentives for applications of our equipment could reduce demand for our equipment and harm our business.

The market for cogeneration equipment depends in part on the availability and size of government and economic incentives that vary by geographic market. Because our sales to customers are typically into geographic areas with such incentives, elimination, or expiration of government subsidies and economic incentives for cogeneration equipment may negatively affect the competitiveness of equipment relative to other sources of electricity, heating, and cooling equipment, and could harm or halt the growth of the cogeneration industry and our business. For example, we are eligible for the New Jersey Smart Start Combined Heat and Power Incentive.

Competing sources of electricity, heating, and cooling equipment may successfully lobby for changes in the relevant legislation in their markets that are harmful to the cogeneration industry. Reductions in, or eliminations or expirations of, governmental incentives in regions where we focus our sales efforts could result in decreased demand for and lower revenue from cogeneration equipment there, which would adversely affect us. In addition, our ability to successfully penetrate new geographic markets may depend on new geographic areas adopting and maintaining incentives to promote cogeneration, to the extent such incentives are not currently in place. Additionally, electric utility companies may establish pricing structures or interconnection requirements that could adversely affect our sales and be harmful to cogeneration.

We may be exposed to substantial liability claims if we fail to fulfill our obligations to our customers or our on-site equipment malfunctions.

We enter into contracts with large commercial and not-for-profit customers under which we assume responsibility for meeting a portion of the customers' building energy demand and equipment installation. We may be exposed to substantial liability claims if we fail to fulfill our obligations to such customers. If the equipment malfunctions, it may be costly to repair or replace. There can be no assurance that we will not be vulnerable to claims by customers and by third parties that are beyond any contractual protections that we are able to negotiate. As a result, liability claims could cause us significant financial harm.

We may be subject to litigation, which is expensive and could divert management attention.

Our share price may be volatile and in the past companies that have experienced volatility in the market price of their stock have been subject to an increased incidence of securities class action litigation. Securities litigation against us could result in substantial costs and divert our management’s attention from other business concerns, which could seriously harm our business.

We are exposed to credit risks with respect to some of our customers.

To the extent our customers do not advance us sufficient funds to finance our costs during the execution phase of our contracts, we are exposed to the risk that they may be unable to accept delivery or that they will be unable to make payment at the time of delivery or within agreed upon payment terms. 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 install receivables which were deemed uncollectible in the year ended December 31, 2023. Our provision for doubtful accounts receivable was $549,206$149,922 as of December 31, 2021, an increase2023, a decrease of $131,206$211,275 when compared to the provision for doubtful accounts as of December 31, 2020.2022. We have experienced customer payment delays due to COVID-19, which are attributable to temporary business shutdowns, resulting in declines in revenues and cash flows from our customers and delays in project completion due to delays in government project inspections and a general slowdown in business activity and in some cases, customers ceasing business activities altogether.

Investment in our Common Stock is subject to price fluctuations and market volatility.

Historically, valuations of many small companies have been highly volatile. The securities of many small companies have experienced significant price and trading volume fluctuations unrelated to the operating performance or the prospects of such companies. The market price of shares of our common stock could be subject to wide fluctuations in response to many risk factors listed in this section, and others beyond our control, including:

Furthermore, during the COVID-19 pandemic and at other times, the U.S. stock markets have experienced extreme price and volume fluctuations that have affected and continue to affect the market prices of equity securities of many companies. These fluctuations often have been unrelated or disproportionate to the operating performance of those companies. These broad market and industry fluctuations, as well as general economic, political, and market conditions such as recessions, interest rate changes, or international currency fluctuations, may negatively impact the market price of shares of our common stock. In addition, such fluctuations could subject us to securities class action litigation, which could result in substantial costs and divert our management’s attention from other business concerns, which could potentially harm our business.

If securities or industry analysts do not publish research or publish inaccurate or unfavorable research about our business, our share price and trading volume could decline.

The trading market for our shares will depend on the research and reports that securities or industry analysts publish about us or our business. There can be no assurance that analysts will cover us or provide favorable coverage. If one or more analysts downgrade our shares or change their opinion of our share price our share price may decline. In addition, if one or more analysts cease coverage of us or fails to regularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.

Because our directors and executive officers are among our largest stockholders, they can exert influence over our business and affairs and have actual or potential interests that may differ from other stockholders or investors.

As of the date of this report, our directors and executive officers collectively beneficially own approximately 13.85%14.8% of our issued and outstanding shares. John Hatsopoulos, a director, beneficially owns approximately 9.45%12.3% of our issued and outstanding shares. Additionally, the holdings of our directors and executive officers may increase in the future upon vesting or exercise of the options or other stock awards they may hold or in the future may be granted or if they otherwise acquire

Such persons’ stock ownership may discourage a potential acquirer from making a tender offer or otherwise attempting to acquire us, which in turn could reduce our stock price or prevent our stockholders from realizing a premium over our stock price.

Current stock holdings may be diluted if we make future equity issuances or if outstanding options are exercised for shares of our common stock.

“Dilution” refers to the reduction in the voting effect and proportionate ownership interest of a given number of shares of common stock as the total number of shares increases. Our issuance of additional stock, convertible preferred stock, or convertible debt may result in dilution to the interests of shareholders and may also result in the reduction of your stock price. The sale of a substantial number of shares into the market, or even the perception that sales could occur, could depress the price of our Common Stock.common stock. Also, the exercise of options may result in additional dilution.

The holders of outstanding options, warrants and convertible securities or derivatives, if any, have the opportunity to profit from a rise in the market price of our shares, if any, without assuming the risk of ownership, with a resulting dilution in the interests of other stockholders. We may find it more difficult to raise additional equity capital if it should be needed for our business while the options, warrants and convertible securities are outstanding.

Future sales of our shares by our existing stockholders may cause our stock price to fall.

The market price of our shares could decline as a result of sales by our existing stockholders of our shares in the market or the perception that these sales could occur. These sales might also make it more difficult for us to conduct an equity or equity-based financing at a time and price that we deem appropriate and thus inhibit our ability to raise additional capital when it is needed.

Because we have not and do not intend to pay cash dividends, our stockholders receive no current income from holding our stock.

We have paid no cash dividends on our capital stock to date and we currently intend to retain our future earnings, if any, to fund the development and growth of our business. We currently expect to retain earnings for use in the operation and expansion of our business, and therefore do not anticipate paying any cash dividends in the foreseeable future. As a result, capital appreciation, if any, of our Common Stock could be the sole source of gain for our stockholders for the foreseeable future.

We incur substantial costs to operate as a public reporting company.

We incur substantial legal, financial, accounting and other costs and expenses to operate as a public reporting company. We believe that these costs are a disproportionately larger percentage of our revenues than they are for many larger companies. In addition, the rules and regulations of the SEC impose significant requirements on public companies, including ongoing disclosure obligations and mandatory corporate governance practices. Our senior management and other personnel need to devote a substantial amount of time to ensure ongoing compliance with these requirements. Our common stock is currently quoted on the OTC Markets Group Inc.’s OTCQX Best Market tier. Under the OTC Markets Group Inc.’s OTCQX continued qualification requirements, we are required to have a minimum bid price of $0.10 per share as of the close of business for at least one of every 30 consecutive calendar days, a market capitalization of at least $5 million for at least one of every 30 consecutive calendar days, and at least two market makers. Also, we must be current in our SEC reporting obligations. If we seek to list our stock for trading on a national securities exchange or be quoted on the Nasdaq Stock Market, we will be subject to additional disclosure and governance obligations. There can be no assurance that we will continue to meet all of the public company requirements to which we are subject on a timely basis, or at all, or that our compliance costs will not continue to be material.

Because our common stock is not traded on a national securities exchange, our stock has limited liquidity and our ability to raise capital is impaired.

On June 19, 2020, we voluntarily delisted our common stock from Nasdaq and transitioned the quotation of our shares to OTC Markets Group Inc.’s OTCQX Best Market. Our common stock has been quoted on the OTC Markets Group Inc.’s OTCQX Best Market since June 19, 2020 under the symbol “TGEN”. We believe that trading “over the counter” has limited our stock’s liquidity and may impair our ability to raise additional capital. Also, and as a result, relatively small trades in our stock could have a disproportionate effect on our stock price.

Certain provisions of our charter and bylaws may discourage mergers and other transactions.

Certain provisions of our certificate of incorporation and bylaws may make it more difficult for someone to acquire control of the company. These provisions may make it more difficult for stockholders to take certain corporate actions and could delay or prevent someone from acquiring our business. These provisions could limit the price that certain investors might be willing to pay for shares of our common stock. The ability to issue “blank check” preferred stock is a traditional anti-takeover measure. This provision may be beneficial to our management and the board of directors in a hostile tender offer and may have an adverse impact on stockholders who may want to participate in such tender offer, or who may want to replace some or all of the members of the board of directors.

Our board of directors may issue additional shares of preferred stock without stockholder approval.

Our certificate of incorporation authorizes the issuance of up to 10,000,000 shares of preferred stock. Accordingly, our board of directors may, without shareholder approval, issue one or more new series of preferred stock with rights which could adversely affect the voting power or other rights of the holders of outstanding shares of our common stock. In addition, the issuance of shares of preferred stock may have the effect of rendering more difficult or discouraging, an acquisition or change of control of the company. Although we do not have any current plans to issue any shares of preferred stock, we may do so in the future.

In order to comply with public reporting requirements, we must continue to strengthen our financial systems and internal controls, and failure to do so could adversely affect our ability to provide timely and accurate financial statements.

Refinement of our internal controls and procedures will be required as we manage future growth and operate effectively as a public company. Such refinement of our internal controls, as well as compliance with the Sarbanes-Oxley Act of 2002 and related requirements, is costly and puts a significant burden on management. We cannot assure you that measures already taken, or any future measures, will enable us to provide accurate and timely financial reports, particularly if we are unable to hire additional personnel in our accounting and financial department, or if we lose personnel in this area. Any failure to improve our disclosure controls or other problems with our financial systems or internal controls could result in delays or inaccuracies in reporting financial information, or non-compliance with SEC reporting and other regulatory requirements, any of which could adversely affect our business and stock price.

Investor confidence in the price of our stock may be adversely affected if we are unable to comply with Section 404 of the Sarbanes-Oxley Act of 2002. As of the end of the period covered by this report, our principal executive officers and our principal financial officer have concluded there is a material weakness in our disclosure controls and procedures and our internal control over financial reporting, which could harm our operating results or cause us to fail to meet our reporting obligations.

As a public company, we are subject to the rules adopted by the SEC pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, which require us to include in our annual report on Form 10-K our management’s report on, and assessment of the effectiveness of, our internal control over financial reporting (“management’s report”). If we fail to achieve and maintain the adequacy of our disclosure control or internal control over financial reporting, there is a risk that we will not comply with all of the requirements imposed by Section 404. Moreover, effective internal control over financial reporting, particularly that relating to revenue recognition, is necessary for us to produce reliable financial reports and is important in helping to prevent financial fraud. Any of these possible outcomes could result in an adverse reaction in the financial marketplace due to a loss in investor confidence in the reliability of our financial statements, which ultimately could harm our business and could negatively impact the market price of our common stock. Investor confidence and the price of our common stock may be adversely affected if we are unable to comply with Section 404 of the Sarbanes-Oxley Act of 2002.

As of the end of the period covered by this Annual Report, December 31, 2021,2023, our principal executive officer and principal financial officer performed an evaluation of our disclosure controls and procedures and concluded that our controls were not effective to provide reasonable assurance that information required to be disclosed by us in reports that we file under

Our intellectual property may not be adequately protected.

We seek to protect our intellectual property rights through patents, trademarks, copyrights, trade secret laws, confidentiality agreements, and licensing arrangements, but we cannot ensure that we will be able to adequately protect our technology from misappropriation or infringement. We cannot ensure that our existing intellectual property rights will not be invalidated, circumvented, challenged, or rendered unenforceable.

Our competitors may successfully challenge the validity of our patents, design non-infringing products, or deliberately infringe our patents. There can be no assurance that other companies are not investigating or developing other similar technologies. In addition, our intellectual property rights may not provide a competitive advantage to us or ensure that our products and technology will be adequately covered by our patents and other intellectual property. Any of these factors or the expiration, termination, or invalidity of one or more of our patents may have a material adverse effect on our business.

Others may assert that our technology infringes their intellectual property rights.

We may be subject to infringement claims from time to time. The defense of any claims of infringement made against us by third parties could involve significant legal costs and require our management to divert time from our business operations. If we are unsuccessful in defending any claims of infringement, we may be forced to obtain licenses or to pay additional royalties to continue to use our technology. We may not be able to obtain any necessary licenses on commercially reasonable terms or at all. If we fail to obtain necessary licenses or other rights, or if these licenses are costly, our operating results would

Our success is dependent upon attracting and retaining highly qualified personnel and the loss of key personnel could significantly hurt our business.

To achieve success, we must attract and retain highly qualified technical, operational and executive employees. The loss of the services of key employees or an inability to attract, train and retain qualified and skilled employees, specifically engineering, operations, and business development personnel, could result in the loss of business or could otherwise negatively impact our ability to operate and grow our business successfully.

Our business may be impacted by political events, war, terrorism, public health issues, natural disasters and other circumstances that are not within our control.

War, terrorism, geopolitical uncertainties, public health issues, and other business interruptions have caused and could cause damage or disruption to international commerce and the global economy, and thus could have a material adverse effect on us, our suppliers, and manufacturing vendors. Our business operations are subject to interruption by natural disasters, fire, power shortages, nuclear power plant accidents, terrorist attacks, and other hostile acts, labor disputes, public health issues, and other events beyond our control. Such events could decrease demand for our products, make it difficult or impossible for us to make and deliver products to our customers, or to receive products from our manufacturers and suppliers, and create delays and inefficiencies in our supply chain. If major public health issues, including pandemics, arise, we could be adversely affected by more stringent employee travel restrictions, additional limitations in freight services, governmental actions limiting the movement of products between regions, delays in production ramps of new products, and disruptions in the operations of our manufacturing vendors and suppliers. In the event of a natural disaster, we could incur significant losses, require substantial recovery time and experience significant expenditures in order to resume operations.

We depend on a small number of customers for a substantial portion of our product revenues. The loss of one or more of these customers, or our inability to collect outstanding receivables from such customers could have a material adverse effect on our financial results.

DuringFor the yearyears ended December 31, 2021,2023 and December 31, 2022, no customer accounted forrepresented more than 10% of our revenues. Duringrevenues for the year endedrespective years. There was one customer who represented 14% of the accounts receivable balance as of our December 31, 2020,2023, and one customer accounted for more than 10% of our revenues. There were two customers who represented more than 10%15% of the accounts receivable balance as of December 31, 2021, and zero customers who accounted for more than 10% of the accounts receivable balance as of December 31, 2020.2022. The loss of any one or more of our major customers or our inability to collect on outstanding accounts receivable from one or more of these customers could have a material adverse effect on our business and financial condition. Our provision for doubtful accounts receivablebad debt expense increased $131,206 to $549,206$902,432 in the year ended December 31, 2021,2023, compared to a benefit of $70,987 in the year ended December 31, 2022, due to the write down of certain install receivables which were deemed uncollectible in the year ended December 31, 2023. Our provision for doubtful accounts receivable decreased $211,275 to $149,922 in the year ended December 31, 2023, compared to the year ended December 31, 2020. We continue to seek to increase our customer base and reduce our reliance on a limited number of customers.2022. Although we are seeking to increase and diversify our customer base and reduce our reliance upon sales to a small number of customers, we expect sales to such customers to continue to constitute a significant portion of our revenues in the near term given we actively pursue large contracts and projects. The loss of any one or more of such customers or an inability to collect such accounts receivable could have a material adverse effect our business, financial condition and results of operations.

None.

Our headquarters is located in Waltham, Massachusetts, and consists of approximately 43,000 square feet of manufacturing, storage and office space. OurOn March 1, 2024, we extended the Waltham lease is for a term that will expirewhich now expires on March 31,April 30, 2024. Currently, our monthly base rent for our Waltham, Massachusetts facility is $43,609.$44,254.

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. We believe that our facilities are appropriate and adequate for our current needs.

Our eleven leased service centers can be broken into two different sizes. The larger leased spaces have office space to accommodate administrative, sales and engineering personnel, and warehouse space to stock parts in support of our service contracts. As of December 31, 2021,2023, the service centers that fit this larger category are based in Piscataway, New Jersey and

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 Company isCorporation 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 represented by Canadian counsel. For the year ended December 31, 2022, we reserved $150,000 for anticipated damages which may not a partybe covered by our insurance and continue to any material pending legal proceeding.maintain the reserve at December 31, 2023.

Not applicable.

Market for Our Shares

Our common stock is quoted on the OTC Markets Group’s OTCQX Best Market tier and trades under the symbol TGEN. As of March 9, 2022,25, 2024, there were 57 holders of record of our common stock. Any over-the-market quotations reflect inter-dealer prices, without mark-up, markdown or commission and may not necessarily represent actual transactions.

We have never declared or paid a cash dividend on our common stock and do not anticipate paying cash dividends on our common stock in the foreseeable future. Payment of future cash dividends, if any, will be at the discretion of our board of directors and will depend on our financial condition, results of operations, contractual restrictions and covenants included under any bank or other indebtedness that we may enter into, capital requirements, business prospects and other factors that our board of directors considers relevant.

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 consultants of the Company.our consultants. The Plan was amended at various dates by the Board of Directors to increase the number ofreserved shares of common stock issuable under the Plan to 3,838,750 as of December 31, 2021,2023, 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 madeissued after January 1, 2016 (the “Amended 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 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, 20212023 and 20202022 was 764,768243,818 and 1,022,768,146,393, respectively.

Overview

Tecogen designs, manufactures, markets, and maintains high efficiency, ultra-clean cogeneration products. These include natural gas engine driven combined heat and power (CHP) systems, chillers and heat pumps for multi-family residential, commercial, recreational and industrial use. We are known for products that provide customers with substantial energy savings, resiliency from utility power outages and for significantly reducing a customer’s carbon footprint. Our products are sold with our patented Ultera® technology which nearly eliminates all criteria pollutants such as NOx and CO. Our systems are greater than 88% efficient compared to typical electrical grid efficiencies of 40% to 50%. As a result, our greenhouse gas (GHG) emissions are typically half that of the electrical grid. Our systems generate electricity and hot water or in the case of our Tecochill product, both chilled water and hot water. These result in savings of energy related costs of up to 60% for our customers. Our products are expected to run on Renewable Natural Gas (RNG) as it is introduced into the US gas pipeline infrastructure.

Our products are sold directly to end-users by our in-house sales team and by established sales agents and representatives. We have agreements in place with distributors and sales representatives. Our existing customers include hospitals and nursing homes, colleges and universities, health clubs and spas, hotels and motels, office and retail buildings, food and beverage processors, multi-unit residential buildings, laundries, ice rinks, swimming pools, factories, municipal buildings, military installations and indoor growing facilities. To date we have shipped over 3,0003,200 units, some of which have been operating for almost 35 years.

Although we may, from time to time, have one or a few customers who may represent more than 10% of our product revenue for a given year, we are not dependent on the recurrence of revenue from those customers. Our product revenue is such that customers may make a large purchase once and may not ever make a purchase again. Our equipment is built to last 30 or more years. Therefore, our product revenue model is not dependent on recurring sales transactions from the same customer. Our service revenue does lend itself to recurring revenue from particular customers, although we currently do not have any service revenue customers who make up more than 10% of our total revenues on an annual basis.customers.

For the last two fiscal years, more than half of our revenue was generated from long-term maintenance and energy production contracts, which provides us with a predictable revenue stream, especially during the summer months. We haveexperience a slight surge of activity from May through September as our “chiller season” is in full swing. Our O&M service

Our product revenue is derived from the sale of the various cogeneration modules, such as the InVerde, InVerde e+, the Tecopower, Ilios heat pumps, and Tecochill products. In 2019, we also reintroduced our TecoFrost refrigeration line. The sales cycle varies between 6 months to a year or more. Therefore, our product revenue can be difficult to predict and the expected margin can vary. In most cases we work with consulting engineers who specify our product in new and retrofit applications. We also work with building owners directly, in some limited cases offering a full turn-key installation.

Our cogeneration, heat pump, and chiller modules are built to order and revenue is recognized upon shipment. The lead time to build and deliver a unit depends on its customized configuration and is approximately 12 to 14 weeks for a chiller and 6 to 8 weeks for a cogeneration system or heat pump, from time of purchase order. As revenue is recognized upon shipment, our work-in-process is an important factor in understanding our financial condition in any given quarter.

Our operations are comprised of three business segments, as follows:

On April 17, 2020,March 15, 2023, we obtainedentered into an unsecured loan in the principal amount of $1,874,200 from Webster Bank, NAagreement ("Webster"Agreement") under the Paycheck Protection Program adoptedwith Aegis Energy Services, LLC (“Aegis”) pursuant to the Coronavirus Aid, Reliefwhich Aegis agreed to assign to us and Economic Recovery Act, as amended ("CARES Act"we agreed to assume certain Aegis maintenance agreements, we agreed to purchase certain assets, and related matters (“Acquisition”). On January 19, 2021April 1, 2023, the Acquisition closed. Under the Agreement, we received confirmationagreed to acquire from Webster thatAegis and assume Aegis' rights and obligations arising on or after April 1, 2023, under maintenance agreements pursuant to which Aegis provided maintenance services for approximately 200 cogeneration systems, and acquired certain vehicles and inventory used by Aegis in connection with the Paycheck Protection Program Loanperformance of such maintenance services, and, following closing hired eight (8) Aegis employees to provide services with respect to such maintenance agreements. At closing, we acquired eight (8) Aegis vehicles for consideration consisting of $170,000 in the original principal amount of $1,874,200 together with accrued interest of $13,659 was forgiven in full effective as of January 11, 2021. The loan forgiveness of $1,887,859 was accounted for as a debt extinguishment and is reported as a separate component of other income (expense), net in our condensed consolidated statement of operations.

On March 27, 2020,During the CARES Act was signed into law providing numerous tax incentives 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. The ERC is available with respect to periods through October 1, 2021 and is equal to 70% of qualified wages (which includes employer qualified health plan expenses) paid to employees. In addition, the availability of the ERC was permitted to entities that received a Paycheck Protection Loan subject to certain conditions. During each quarter in 2021, a maximum of $10,000 in qualified wages for each employee is eligible for the ERC. Therefore, the maximum tax credit that can be claimed by an eligible employer in 2021 is $7,000 per employee per calendar quarter. Section 2301(c)(2)(B) of the CARES Act permits an employer to use an alternative quarter to calculate gross receipts and the employer may determine if the decline in gross receipts tests is met for a calendar quarter in 2021 by comparing its gross receipts for the immediately preceding calendar quarter with those for the corresponding calendar quarter in 2019. Accordingly, for the firstthird quarter of 2021 we elected to use our gross receipts for the fourth calendar quarter of 2020 compared to our gross receipts for the fourth calendar quarter of 2019. As a result of our election to use an alternative quarter, 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 500 or fewer full-time employees in 2019, all wages paid to employees in the first,

On March 5, 2019,July 20, 2022, we transferred ownershipannounced our intention to focus on opportunities for low carbon Controlled Environment Agriculture ("CEA"). We believe that CEA offers an exciting opportunity to apply our expertise in clean cooling, power generation, and greenhouse gas reduction to address critical issues affecting food and energy security. We propose to address this challenge by developing a highly efficient energy solution for CEA grown produce using our cogeneration products in conjunction with solar energy generation, energy storage, and other technologies.

CEA facilities enable multiple crop cycles (15 to 20 cycles) in one year compared to one or two crop cycles in conventional farming. In addition, growing produce close to the point of our energy systems assetssale reduces food spoilage during transportation. Food crops grown in greenhouses typically have lower yields per square foot than in CEA facilities, and related energy production contractsthe push to situate facilities close to consumers in cities requires minimizing land area and maximizing yield per square foot. Yields are increased in CEA facilities by supplementing or replacing natural light with grow lights in a sale transactionclimate-controlled environment - which requires significant energy use.

In recent years our cogeneration equipment has been used in considerationnumerous cannabis cultivation facilities because our systems significantly reduce operating costs, reduce the facility GHG footprint and offer resiliency to grid outages. Our experience providing clean energy solutions to cannabis cultivation facilities has given us significant insight into requirements relating to energy-intensive indoor agriculture applications that we expect to be transferable to CEA facilities for approximately $5 million. In connection with the sale, we entered into two separate agreements to provide operational and maintenance services for the purchaser. Concurrently, we amended the terms of an agreement related to certain energy systems related assets and related energy production contracts, the ownership of which were transferred to the same purchaser in December 2018 in consideration of approximately $2 million, in order to conform and finalize the terms of the agreement to the March 2019 agreement. See Note 5. "Sale of Energy Producing Assets and Goodwill Impairment" in the Notes to our Consolidated Financial Statements for further discussion. In October 2021 the minimum guarantee with respect to one of the energy purchase agreements was modified by reducing the guaranteed minimum collections by $35,000 per year, the guaranteed minimum collection amount associated with one site that was sold by the customer.food production.

Our discussion and analysis of our financial condition and results of operations are based upon our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States. The preparation of these financial statements requires us to make judgments, assumptions and estimates that affect the reported amounts of assets, liabilities, sales and expenses, and related disclosure of contingent assets and liabilities. These judgments, assumptions and estimates are made or applied within the context of accounting policies related to the nature of the transaction. Note 2. "Summary of Significant Accounting Policies" of the Notes to our Consolidated Financial Statements describes the significant accounting policies used in the preparation of the consolidated financial statements.  

Certain aspects of certain accounting policies require management to make difficult, subjective or complex judgments that could have a material effect on our financial condition and results of operations. These aspects of these accounting policies are considered critical accounting policies. These policies may require management to make assumptions about matters that are highly uncertain at the time of the estimate or employ an estimate where alternative estimates could have also been employed, and may involve estimates that are reasonably likely to change with the passage of time. Estimates and assumptions about future events and their effects cannot be determined with certainty.  We base our estimates on historical experience and on various other assumptions believed to be applicable and reasonable under the circumstances.  These estimates may change as new events occur, as additional information is obtained and as our operating environment changes.  These changes have historically been minor and have been included in the consolidated financial statements as soon as they became known.  In addition, management is periodically faced with uncertainties, the outcomes of which are not within its control and will not be known for prolonged periods of time.  These uncertainties are discussed in "Item 1A," “Risk Factors" above.

Management believes that the following are critical accounting policies:estimates:

Revenue Recognition

Revenue is recognized when performance obligations under the terms of a contract with our customer are satisfied. This generally 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.

Determination of contract consideration allocatable to multiple performance obligations within a single contract requires employing stand-alone selling prices which may be based on observable selling prices, estimated selling prices or as a residual. 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.

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.

Property, Plant and Equipment

Property, plant and Depreciation

We review our energy systemsproperty, 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. The useful lifeIf the sum of the Company's energy systemsprojected undiscounted cash flows (excluding interest charges) is less than the lessercarrying value of the economic life ofassets, the asset orassets will be written down to the term ofestimated fair value and such loss is recognized in income from continuing operations in the underlying contract withperiod in which the customer, typically 12 to 15 years.determination is made. If impairment is indicated, the asset is written down to its estimated fair value.

Contract Assets and Liabilities

The favorable contract asset and unfavorable contract liability included in the intangible assets and liabilities of the consolidated balance sheets represent the fair value of customer energy production contracts (both positive for favorable contracts and negative for unfavorable contracts) which were acquired by us.

The determination of fair value requires development of an estimate of the price at which an orderly transaction to sell the asset or to transfer the liability would take place between market participants at the measurement date under current market conditions. Contracts are considered to be assets or liabilities by virtue of the rights and obligations inherent in the contract terms. Typically, contracts with terms considered to be at market are considered to have no fair value as, in order to be entitled to the rights under the contract, performance must occur for which a market rate of return is earned due to the at market terms. The fair value of a contract is primarily a measurement of its off-market terms. The obligation to perform under a contract with terms that are unfavorable to market results in a liability to the extent its terms are off market. The resulting liability is an estimate of the price that would need to be paid to a willing market participant to assume the obligations under the contract in order for them to receive a market rate of return for their remaining performance obligation under the contract. The exact opposite holds true in instances where the terms of a contract are considered to be favorable to market. In that case an asset would exist as an estimate of the price that would be received from a willing market participant in order to be entitled to the rights under the contract.

In determining the estimate of fair value of customer energy production contracts, the measure of market, and thus the baseline to measure the amount related to any of the off-market terms or conditions with respect to the contracts, was considered best determined, given the nature of the services provided under the contracts, by utilizing a benchmark level of margin, in this case 35% of revenue which is consistent with the average return on revenue of US investor owned public utilities.

Goodwill is not amortized; however, it is reviewed for impairment annually in the fourth quarter and/or when circumstances or other events indicate that impairment may have occurred. ASC 350 “Intangibles—Goodwill and Other” (ASC 350) permits entities to make a qualitative assessment of whether it is more likely than not that a reporting unit’s fair value is less than its carrying amount before applying the two-step goodwill impairment test. Circumstances that are considered as part of the qualitative assessment and could trigger the two-step impairment test include, but are not limited to: a significant adverse change in the business climate; a significant adverse legal judgment; adverse cash flow trends; an adverse action or assessment by a government agency; unanticipated competition; decline in our stock price; and a significant restructuring charge within a reporting unit. We define reporting units at the business segment level. For purposes of testing goodwill for impairment, goodwill has been allocated to our reporting units to the extent it relates to each reporting unit.

During 2018, we early-adoptedadopted the provisions of ASU 2017-04 which simplified goodwill impairment testing by eliminating the requirement to determine the implied value of goodwill where a quantitative analysis indicates that the carrying value of the reporting unit exceeds its fair value.

At a minimum, we perform a quantitative goodwill impairment test in the fourth quarter of the year following an acquisition involving a significant amount of goodwill.year. In the fourth quarter of 2020,2023, we performed a quantitative goodwill impairment test for our energy production reporting unit acquired in 2017. We used a discounted cash flow approach to develop the estimated fair value of that reporting unit. Management judgment is required in developing the assumptions for the discounted cash flow model. An impairment would be recorded if the carrying amount of a reporting unit including goodwill exceeded the estimated fair value. Based on the aforementioned analysis, the carrying amount of that reporting unit, including goodwill, exceeded the estimated fair value and an impairment charge of $2,875,711 was recorded in the fourth quarter of 2020. We performed a quantitative goodwill impairment test of our energy production reporting unit in the fourth quarter of 2021, utilizing a discounted cash flow approach to estimate fair value of the reporting unit. Based on this analysis there was no impairment at December 31, 2021.2023. See Note 5.6. "Sale of Energy Producing Assets and Goodwill Impairment".

The impairment analysis recognizes the shortening of remaining contract terms with customers without replacement and without further growth, as well as less than expected cost savings, and, offset by profitability from our initiatives to optimize the long-term profitability of our various site operations and a price peak of the Company's stock on the date of the business combination to which the goodwill relates (see also Note 5.6."Sale of Energy Producing Assets and Goodwill Impairment").

The discount rate, profitability assumptions, and terminal growth rate of this reportingthe Energy Production unit were the material assumptions utilized in the discounted cash flow model used to estimate its fair value. The discount rate reflects an estimate of our weighted-average cost of capital.

The discounted cash flow analysis requires estimates, assumptions and judgments about future events. Our analysis uses our internally generated long-range plan. The long-range plan reflects management's judgment and assumptions about future events.

We believe the assumptions used in our goodwill impairment analysis are appropriate and result in a reasonable estimate of the fair value of the reporting unit. However, given the economic environment and the uncertainties regarding the impact on our business, there can be no assurance that our estimates and assumptions, made for purposes of our goodwill impairment testing, will prove to be an accurate prediction of the future. If our assumptions regarding future performance are not achieved, we may be required to record additional goodwill impairment charges in future periods.

Results of Operations

Year Ended December 31, 20212023 Compared to Year Ended December 31, 20202022

The following table sets forth for the periods indicated, the percentages of the net sales represented by certain items reflected in our statements of operations for the years ended December 31, 20212023 and 2020:2022:

The following table presents revenue by segment and the change from the prior year for the years ended December 31:31, 2023 and 2022:

Revenues in 20212023 were $24,398,073$25,139,419 compared to $28,254,579$25,002,614 in 2020,2022, an increase of $136,805 or 0.5% due to increased Services revenues which were offset by decreased Products revenues.

Product revenues in 2023 were $8,859,946 compared to $11,156,099 in 2022, a decrease of $3,856,506$2,296,153 or 13.6%20.6%. Product revenuesThe revenue decrease in 2021 were $10,133,3292023 compared to $11,466,716 in 2020, a decrease of $1,333,387 or 11.6%. This decrease from the year ended December 31, 2020 to 20212022 is due primarily to a decrease in cogeneration sales of $5,969,300$2,517,902, due to decreased unit volume and a $47,596 decrease in sales of engineered accessories, which isare partially offset by an increase in chiller sales of $4,422,674 and a $213,239 increase in sales of engineered accessories.$269,345. Our product mix, as well as product revenue, can vary significantly from period to period as our products are high dollar, low volume sales in which revenue is recognized upon shipment and to some degree were impacted by COVID-19 as energy and other constructions projects were delayed.shipment.

Revenues derived from our service centers, including installation activities, in 20212023 were $12,525,594$14,523,054 compared to $14,950,682$12,060,661 for the same period in 2020,2022, an increase of $2,462,393 or 20.4%. The increase in revenue in 2023 is due primarily to the addition of $1,884,891 in revenue from the acquired Aegis maintenance contracts and a decrease$577,502 or 4.8%, increase in service contract revenues from existing contracts.

Our service operation growsrevenues grow with the sales of installed systems, since the majority of our product sales are accompanied by a service contract or time and materials agreements. As a result, our “fleet” of units being serviced by our service department grows with product sales.

Energy Production

Energy production revenues for the year ended December 31, 20212023 were $1,739,150$1,756,419 compared to $1,837,181$1,785,854 for 2020,2022, a decrease of $98,031,$29,435, or 5.3%1.6%.

Cost of sales in 2023 was $14,937,801 compared to $13,935,803 in 2022, an increase of $1,001,998 or 7.2%. This reductionThe increase in cost of sales is due to increased Services revenue volume, the impact of inflation on our material costs, an increase in the provision for obsolete inventory and increased product warranty costs. Our overall gross margin was 40.6% in 2023 compared to 44.3% in 2022, a decrease of 3.7%.

Energy Production revenue is

Cost of sales for energy production for the year ended December 31, 2023 was $1,105,503 compared to $996,990 in 2022, an increase of $108,513. Energy production gross margin was 37.1% in 2023 compared to 44.2% in 2022, a decrease of 7.1%, primarily due to seasonal variations, the impactincreased fuel and maintenance costs.

Operating expenses increased in 2023 to $14,615,230 compared to $13,415,952 in 2022, an increase of COVID-19 resulting$1,199,278 or 8.9%.

General and administrative expenses increased $971,138 to $11,880,389 in the permanent closureyear ended December 31, 2023 compared to $10,909,251 in 2022 due primarily to a $974,420 increase in bad debt expense, due mainly to the write down of some hotel propertiescertain install receivables which were deemed uncollectible, a $139,364 increase in amortization and depreciation, due to the Aegis acquisition, a change$164,415 increase in business insurance, partially offset by a $83,758 decrease in stock-based compensation, a $68,470 decrease in franchise taxes and the $150,000 litigation provision recorded in 2022.

Selling expenses increased in the year ended December 31, 2023 to remote work and learning environments, resulting$1,931,037 compared to $1,811,085 in decreased energy usage.2022, an increase of $119,952 due primarily to a $101,826 increase in trade show expense.

Gains on the sale of assets of $10,486 were recognizedwas $36,207 in 2021 in connection with the sale of certain assets, which compares2023 compared to a gain on the sale of assets of $11,367 recognized$41,931 in 2020 due to the sales of certain assets.2022.

Impairment of long-lived assets decreased $244,506 to $7,400$4,674 in the year ended December 31, 20212023 compared to $251,906 in 2020 due primarily to the impairment of certain energy production assets and the abandonment of patent applications recorded in 2020.

Loss from operations for the year ended December 31, 20212023 was $1,219,092$4,413,612 compared to a loss of $5,960,313$2,349,141 in 2020, a decrease2022, an increase in the loss from operations of $4,741,221.$2,064,471. The decreaseincrease in the net loss from operations is primarily due to lower Products sales, a $865,193 decrease in gross margin due to higher products material costs and the goodwill impairment of $2,875,711increased provision for obsolete inventory and a decrease in long-lived asset impairment of $244,506 when compared to 2020, as discussed in Note 9."Goodwill", Note 7. "Intangible assets and liabilities other than goodwill" and Note 8. "Property, plant and equipment"in the accompanying consolidated financial statements. Improvement in loss from operations was also helped by the higher gross gross margin of 47.5% in 2021 compared to 38.3% in 2020, and a 23.7% reduction$1,199,278 increase in operating costs.expenses.

Other income,expense, net, for the year ended December 31, 20212023 was $4,979,600$77,053 compared to an expenseincome of $226,707$32,219 for the same period in 2020. The extinguishment2022, a decrease of Paycheck Protection Program debt and the Employee Retention Credit contributed $3,773,014 and $1,276,021 for the year ended December 31, 2021. Other income (expense) includes$44,834, due to an increase in interest and other expense

With the addition of American DG Energy, weWe have income and losses attributable to the noncontrolling interest we have in American DG Energy's 51% owned subsidiary, ADGNY, LLC. The noncontrolling interest share of ADGNY profits and losses was a $45,017 income of $74,952 for the year ended December 31, 20212023 and lossincome of $66,684$50,215 in 2020. The noncontrolling interest recognized a loss in the year ended December 31, 2020 due to the goodwill impairment recognized.2022.

Net incomeloss for the year ended December 31, 20212023 was $3,696,000$4,598,108 compared to a net loss of $6,150,507$2,447,927 for the comparable period in 2020. This was2022. The increase in net loss in 2023 is primarily due to lower Products sales, a $865,193 decrease in gross margin due to higher products material costs and the Paycheck Protection Program loan forgivenessincreased provision for obsolete inventory and Employee Retention Credit contributing $3,773,014 and $1,276,021 respectivelya $1,199,278 increase in 2021. Additionally, the reduction in loss from operations of $4,741,221 or 79.5% further contributed to a profitable 2021.operating expenses.

Net incomeloss per share for the year ended December 31, 20212023 was $0.15a loss of $0.19 compared to a $0.25 loss of $0.10 per share for the same period in 2020.2022. The basic and diluted weighted average shares outstanding for the year ended December 31, 20212023 were 24,850,261 and 25,115,518,24,850,261, respectively. For the year ended December 31, 2020,2022, basic and diluted shares were 24,850,258.24,850,261 and 24,850,261, respectively.

The following table presents a summary of our net cash flows from operating, investing, and financing activities:

Consolidated working capital at December 31, 20212023 was $16,193,881,$9,822,546, compared to $13,023,598$14,344,288 at December 31, 2020, an increase2022, a decrease of $3,170,283$4,521,742 or 24.3%31.5%. Included in working capital were cash and cash equivalents of $3,614,463$1,351,270 at December 31, 2021,2023, compared to $1,490,219$1,913,969 at December 31, 2020, an increase2022, a decrease of $2,124,244$562,699 or 142.5%29.4%. The increasedecrease in consolidated working capital is primarily due to the second draw Paycheck Protection Program loanincrease in our net loss and positive cash flow from operations.increased liabilities recognized due to the Aegis contract acquisition.

Net cash provided by operating activities forFor the yearsyear ended December 31, 2021 and 2020 were $465,033 and $1,407,237, respectively,2023 we used $823,315 in cash from operations compared to $1,351,929 in cash used from operations in 2022, a decrease of $942,204$528,614 in net cash providedused by operating activities. Our accounts receivable balance decreasedincreased by $57,618$81,195 at December 31, 20212023 compared to December 31, 2020. Unbilled2022 and our unbilled revenues also decreased by $1,009,060 $56,994

Accounts payable decreasedincreased by $674,750$1,161,416 from December 31, 20202022 to December 31, 2021.2023 due to increased aging of our payables to conserve liquidity. Accrued expenses from operations decreasedincreased by $602,073$128,869 as of December 31, 20212023 compared to December 31, 20202022 due to lowerhigher operating expenses. Deferred revenues decreasedincreased by $756,722$543,842 as of December 31, 20212023 as compared to December 31, 2020.2022, due to Aegis contract customer deposits collected in 2023 .

During 2021, ourFor the year ended December 31, 2023 we used $244,889, in cash flows used byfrom investing activities, were $215,058, and includedconsisting of $170,000 of cash to acquire certain assets as part of the Aegis acquisition, used $46,851 of cash for purchases of property and equipment, and distributed $62,693 to the 49% non-controlling interest holders of $91,451, distributions to non-controlling interestsAmerican DG New York LLC.

Cash flows from financing activities in 2023 were $505,505, consisting of $82,633, capital outlaysborrowings under our related to intangible assets such as patents and product certification of $63,097.

Our total product and installation backlog as of December 31, 20212023 was $11.3 million$7,388,145 compared to $8.3 million$6,722,138 as of December 31, 2020.2022. Backlog does not include maintenance contract service revenues or energy contract revenues.

Based on our current operating plan, we believe existing resources, including cash and cash flows from operations together with the $1,276,021 of proceeds anticipated to be received from the Employee Retention Credit, will be sufficient to meet our working capital requirements for the next twelve months. However, if we seekIn order to grow our business and fund the development of our hybrid-drive air-cooled chiller and the relocation of our primary facility, we expect that our cash requirements will increase. As a result,increase and we may need to raise additional capital through a debt or equity financing to meet our operatingneed for capital to fund operations and capital needs for future growth.

Contractual Obligations and Commitments

Seasonality

We expect that the majority of our heating systems sales will be operational for the winter and the majority of our chilling systems sales will be operational for the summer. Our cogeneration sales are not generally affected by the seasons. Our service team does experience higher demand in the warmer months when cooling is required. Chiller units for space conditioning applications are generally shut down in the winter and started up again in the spring. This chiller “busy season” for the service team generally runs from May through the end of September. Chillers in indoor cultivation and other process cooling applications run year round.

The information required by this item is incorporated from Item 15 and pages F-1 through F-25 of this Annual Report on Form 10-K.

None.

Management’s Evaluation of Disclosure Controls and Procedures: 

Our disclosure controls and procedures are designed to provide reasonable assurance that the control system’s objectives will be met. Our management, including our Chief Executive Officer and Principal Financial Officer, after evaluating the effectiveness of our disclosure controls and procedures as of December 31, 20212023 ("Evaluation Date"), havehas concluded that as of the Evaluation Date, our disclosure controls and procedures were not effective due to the material weakness in financial reporting relating to a small number of employees dealing with general controls over information technology. Our management has decided that the expense associated with continued implementation of new systems is justified and continues to implement systems to put the proper control procedures in place to remediate this weakness.

For these purposes, the term disclosure controls and procedures of an issuer means controls and other procedures of an issuer that are designed to ensure that information required to be disclosed by the issuer in the reports that it files or submits under Section 13(a) or 15(d) of the Securities Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include, without limitation, controls and procedures designed to ensure that information required to be disclosed by an issuer in the reports that it files or submits under Section 13(a) or 15(d) of the Securities Exchange Act is accumulated and communicated to the issuer’s management, including its principal executive and principal accounting officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure.

Management’s Annual Report on Internal Control over Financial Reporting:

Our management is responsible for establishing and maintaining adequate internal controls over financial reporting as defined in Rules 13a-15(f) under the Securities Exchange Act of 1934, as amended.

Because of its inherent limitations, internal control over financial reporting, no matter how well designed, may not prevent or detect misstatements. Accordingly, even effective internal control over financial reporting can provide only reasonable assurance with respect to financial statement preparation. Also, the assessment of the effectiveness of internal control over financial reporting was made as of a specific date. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Management, including our Chief Executive Officer and Principal Financial Officer, conducted an evaluation of our internal control over financial reporting based on the framework and criteria established in Internal Control—Integrated Framework, issued by the Committee of Sponsoring Organizations of the Treadway Commission. This evaluation included review of the documentation of controls, evaluation of the design effectiveness of controls, testing of the operating effectiveness of controls and a conclusion regarding this evaluation. Based on this evaluation, management concluded that our internal control over financial reporting was not effective as of December 31, 2021.

Our management, including our Chief Executive Officer and Principal Financial Officer, does not expect that our disclosure controls or our internal control over financial reporting will prevent or detect all errors and all fraud. A control system, no matter how well designed and operated, can provide only reasonable, not absolute, assurance that the control system’s objectives will be met. The design of a control system must reflect the fact that there are resource constraints, and the benefits of controls must be considered relative to their costs. Further, because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that misstatements due to error or fraud will not occur or that all control issues and instances of fraud, if any, within the Company have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty and that breakdowns can occur because of a simple error or mistake. Controls can also be circumvented by the individual acts of some persons, by collusion of two or more people, or by management override of the controls. The design of any system of controls is based in part on certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions. Projections of any evaluation of controls effectiveness to future periods are subject to risks. Over time, controls may become inadequate because of changes in conditions or deterioration in the degree of compliance with policies or procedures.

This annual report does not include an attestation report of our registered independent public accounting firm regarding internal control over financial reporting. Management’s report was not subject to attestation by our registered independent public accounting firm pursuant to rules of the Securities and Exchange Commission that permit us to provide only management’s report in this Annual Report on Form 10-K.

Changes in Internal Control Over Financial Reporting

We implemented a company-wide ERP system in 2019. We continue to make progress in remediating internal control weaknesses. There has been no change to our internal control over financial reporting (as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act) during the fourth quarter of the fiscal year ended December 31, 20212023 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

The information required by this Item is incorporated by reference to our 20222024 definitive proxy statement to be filed with the SEC within 120 days following the registrant's fiscal year ended December 31, 2021.2023.

The information required by this Item is incorporated by reference to our 20222024 definitive proxy statement to be filed with the SEC within 120 days following the registrant's fiscal year ended December 31, 2021.2023.

The information required by this Item is incorporated by reference to our 20222024 definitive proxy statement to be filed with the SEC within 120 days following the registrant's fiscal year ended December 31, 2021.2023.

Item 13. Certain Relationships and Related Transactions, and Director Independence.

The information required by this Item is incorporated by reference to our 20222024 definitive proxy statement to be filed with the SEC within 120 days following the registrant's fiscal year ended December 31, 2021.2023.

The information required by this Item is incorporated by reference to our 20222024 definitive proxy statement to be filed with the SEC within 120 days following the registrant's fiscal year ended December 31, 2021.

The following are filed as part of this Annual Report on Form 10-K.

    Report of Independent Registered Public Accounting Firm

Consolidated Balance Sheets as of December 31, 20212023 and 20202022

Consolidated Statements of Operations for the years ended December 31, 20212023 and 20202022

Consolidated Statements of Stockholders' Equity for the years ended December 31, 20212023 and 20202022

Consolidated Statements of Cash Flows for the years ended December 31, 20212023 and 20202022

Notes to Audited Consolidated Financial Statements

All other schedules for which provision is made in the applicable accounting regulations of the SEC are not required under the related instructions, or are inapplicable, and therefore have been omitted.

The exhibits are listed in the Exhibit Index attached hereto and incorporated by reference herein.

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