As previously disclosed, Tecogen Inc. (the “TGEN”) filed a registration statement on Form S-4, which contains a proxy statement of American DG Energy Inc., (the “Company’) and a prospectus of TGEN (the “Registration Statement”), with the Securities and Exchange Commission (the “SEC”). On April 12, 2017, the Registration Statement was declared effective by the SEC, and the Company announced that a special meeting of the Company’s stockholders (the “Special Meeting”) is scheduled to be held on May 18, 2017, at 1 p.m., Eastern Time, at the Company’s principal executive offices at 45 First Avenue, Waltham, Massachusetts 02451, to consider and vote on (1) a proposal to adopt the Agreement and Plan of Merger, dated as of November 1, 2016, as the same may be amended from time to time (the “Merger Agreement”), by and among the Company, TGEN, and TGEN.ADGE Acquisition Corp., a Delaware corporation formed for the purpose of effecting the merger, and a wholly-owned subsidiary of TGEN (the “Merger Sub”), to where Merger Sub will merge with and into the Company, or the Merger, with the Company continuing as the surviving entity (the “Merger”), approval of the transactions contemplated thereby, including the Merger, and (2) a proposal to approve the adjournment or postponement of the Special Meeting, if necessary or appropriate, to solicit additional proxies. Stockholders of record of the Company at the close of business on April 24, 2017, will be entitled to vote by proxy or in person at the Special Meeting. The proxy statement is expected to be mailed to stockholders of record on or about May 4, 2017.

Completion of the Merger is subject to certain conditions, including approval by the Company’s stockholders and other customary closing conditions.

A copy of the press release is furnished as Exhibit 99.1 hereto and incorporated herein by reference.

CAUTIONARY NOTE REGARDING FORWARD LOOKING STATEMENTS

This Current Report on Form 8-K, or this Current Report, contains forward looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other securities laws. The forward looking statements are subject to various known and unknown risks, uncertainties and other factors. When the Company uses words such as “believes,” “expects,” “anticipates,” “estimates,” “plans” or similar expressions, the Company is making forward looking statements. Although the Company believes that its forward-looking statements are based on reasonable assumptions, its expected results may not be achieved, and actual results may differ materially from its expectations. For example, this Current Report states the date that the Company expects to mail the proxy statement to its stockholders and the date of the Special Meeting. These dates could change and the mailing and/or the date of the Special Meeting could be delayed.

You should not rely upon forward-looking statements except as statements of the Company’s present intentions and of the Company’s present expectations, which may or may not occur. You should read these cautionary statements as being applicable to all forward-looking statements wherever they appear. Except as required by law, the Company undertakes no obligation to release publicly the result of any revision to these forward-looking statements that may be made to reflect events or circumstances after the date hereof or to reflect the occurrence of unanticipated events. Readers are also urged to carefully review and consider the various disclosures the Company has made in this document as well as the Company’s other filings with the SEC, including the sections captioned “Risk Factors” and “Cautionary Note Regarding Forward Looking Statements” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 filed with the SEC on March 21, 2017.

Additional Information

This Current Report may be deemed to be solicitation material in respect of the proposed stockholder vote approving the Merger. The Company has filed with the SEC a Registration Statement on Form S-4, which Registration Statement will include a definitive proxy statement of the Company, a definitive proxy statement of ADGE and prospectus of the Company (when available). The Registration Statement was declared effective by the SEC on April 12, 2017. Notice of the Special Meeting and a definitive proxy statement/prospectus is expected to be mailed on or about May 4, 2017, to stockholders of the Company as of April 24, 2017. BEFORE MAKING ANY VOTING DECISION, THE COMPANY’S STOCKHOLDERS ARE URGED TO READ ALL RELEVANT DOCUMENTS FILED WITH THE SEC, INCLUDING, WHEN AVAILABLE, THE DEFINITIVE PROXY STATEMENT/PROSPECTUS, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE MERGER. Stockholders will be able to obtain, without charge, a copy of the definitive proxy statement/prospectus (when available) and other documents that the Company and ADGE file with the SEC from the SEC’s website at www.sec.gov. The definitive proxy statement/prospectus (when available) and other relevant documents will also be available, without charge, by directing a request by mail or telephone to Attn: Bonnie Brown, 45 First Ave., Waltham, MA 02451, 781-522-6020, or from the Company’s website, http://americandg.com/.

The Company, TGEN, their respective directors and executive officers and certain other members of their management and employees may be deemed to be participants in the solicitation of proxies in connection with the Special Meeting at which the Company’s stockholders will have the opportunity to vote on the proposed Merger. Additional information regarding the interests of such potential participants will be included or incorporated by reference in the definitive proxy statement/prospectus (when available).

About AMERICAN DG ENERGY INC. (NYSEMKT:ADGE)

American DG Energy Inc. distributes, owns and operates clean, onsite energy systems that produce electricity, hot water, heat and cooling. It offers natural gas-powered cogeneration systems. It offers energy producing products, such as natural gas heat pumps, complementary energy equipment, such as boilers, and alternative energy equipment, such as solar and fuel cells. Its cogeneration systems produce electricity from an internal combustion engine driving a generator, while the heat from the engine and exhaust is recovered and typically used to produce heat and hot water for use on-site. It also distributes and operates water chiller systems for building cooling applications. It has installed energy systems, representing approximately 8,323 kilowatts of heat and hot water, and approximately 4,525 tons of cooling. It provides a range of combined heat and power (CHP) products and energy options. The Company sells energy under long-term contracts.

AMERICAN DG ENERGY INC. (NYSEMKT:ADGE) Recent Trading Information

AMERICAN DG ENERGY INC. (NYSEMKT:ADGE) closed its last trading session up +0.018 at 0.320 with 115,746 shares trading hands.