Tecogen's Co-CEO to Retire as an Officer and Board Member, Will Continue in an Emeritus and Advisory Role

WALTHAM, MA--(Marketwired - December 29, 2017) - December 29, 2017- Tecogen® Inc. (NASDAQ: TGEN), a clean energy company providing ultra-efficient, clean, natural gas powered on-site power, heating and cooling equipment, is announcing that John Hatsopoulos, the company's Co-CEO and co-founder, has decided to retire as an officer and not run for re-election to the Board of Directors of Tecogen Inc. at the 2018 annual meeting. He will remain a Director of American DG Energy (ADGE) and Ultera Technologies, Inc. He will also continue to be actively involved with the company as an advisor to the board and Co-CEO Benjamin Locke and as an employee responsible for investor relations. Upon his retirement, Mr. Hatsopoulos will assume the title of Chairman Emeritus.

About Tecogen
Tecogen® Inc. designs, manufactures, sells, installs, and maintains high efficiency, ultra-clean, cogeneration products including natural gas engine-driven combined heat and power, air conditioning systems, and high-efficiency water heaters for residential, commercial, recreational and industrial use. The company is known for cost efficient, environmentally friendly and reliable products for energy production that, through patented technology, nearly eliminate criteria pollutants and significantly reduce a customer's carbon footprint.

In business for over 30 years, Tecogen has shipped more than 2,500 units, supported by an established network of engineering, sales, and service personnel across the United States. For more information, please visit www.tecogen.com or contact us for a free Site Assessment.

Tecogen, InVerde, Ilios, Tecochill, Ultera, and e⁺, are registered trademarks or trademark pending registration of Tecogen Inc.

Forward Looking Statements
This press release and any accompanying documents, contains "forward-looking statements" within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words such as: "anticipate," "intend," "plan," "goal," "seek," "believe," "project," "estimate," "expect," "strategy," "future," "likely," "may," "should," "will" and similar references to future periods. Examples of forward-looking statements include, among others, statements we make regarding:

• The future structure and funding of Tecogen and any of its joint ventures.
• The status of any intellectual property rights or assets.
• Expected operating results, such as revenue growth and backlog.
• Strategy for growth, product development, and market position. AND
• Strategy for risk management.\

Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based only on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, projections, anticipated events and trends, the economy and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control. Our actual results and financial condition may differ materially from those indicated in the forward-looking statements. Therefore, you should not rely on any of these forward-looking statements. Important factors that could cause our actual results and financial condition to differ materially from those indicated in the forward-looking statements include, among others, the following:

• Competing technological developments.
• Lack of market interest in our joint venture's products.
• Issues obtaining intellectual property protection.
• Issues in the research and development of new products.
• Tecogen's inability to properly fund its joint ventures. AND
• Such other factors as discussed throughout the "Risk Factors" section of Tecogen's 10-K that was filed with the SEC on March 31, 2017 and can be found at www.sec.gov.

Any forward-looking statement made by us in in this press release and any accompanying documents is based only on information currently available to us and speaks only as of the date on which it is made. We undertake no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.