Tecogen Appoints New Executives WALTHAM, MA--(Mark

WALTHAM, MA --(Marketwired - May 25, 2017) - Tecogen Inc. ( NASDAQ : TGEN ) today announced the appointment of Bonnie Brown to Chief Accounting Officer. Ms. Brown served as the Chief Financial Officer of American DG Energy which recently merged with Tecogen. Prior to joining American DG Energy, Ms. Brown served as the Chief Financial Officer of Tecogen and was instrumental in successfully taking the Company public. Ms. Brown is a senior level executive with over 20 years of hands-on experience in finance, management, tax, and business leadership. Ms. Brown holds a B.S. in Accountancy from Bentley College, a M.S. in Computer Information Systems from Boston University and is a Certified Public Accountant.

"Now that we have finalized the acquisition of American DG Energy, we look forward to Bonnie bringing her depth of knowledge and experience once again to Tecogen at this crucial phase in the company's development," said Ben Locke, Co-CEO.

Tecogen is also pleased to announce the appointment of Jeb Armstrong as Director of Capital Markets. Mr. Armstrong will be instrumental in expanding our investment strategy and investor development initiatives. He has 15 years of experience working in the energy sector, most recently as Senior Energy Analyst at The Marwood Group as well as the Energy Investment Consultant at Clear Harbor Asset Management. Mr. Armstrong holds a B.A in Political Science from Haverford College and an M.B.A. in Finance from NYU-Stern.

"I am delighted to have Jeb join the team. He brings to Tecogen substantial experience as both a sell-side analyst and an investor in alternative energy companies. I look forward to working with him as we communicate with our existing investors and grow the awareness of Tecogen's highly prospective outlook more broadly," said John Hatsopoulos, Co-CEO.

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 may contain forward-looking statements under the Private Securities Litigation Reform Act of 1995 that involve a number of risks and uncertainties. Important factors could cause actual results to differ materially from those indicated by such forward-looking statements, as disclosed on the Company's website and in Securities and Exchange Commission filings. The statements in this press release are made as of the date of this press release, even if subsequently made available by the Company on its website or otherwise. The Company does not assume any obligation to update the forward-looking statements provided to reflect events that occur or circumstances that exist after the date on which they were made.