Exhibit



TECOGEN INC. 45 FIRST AVE WALTHAM, MA 02451 ATTN: DAVID GARRISON	VOTE BY INTERNET - www.proxyvote.com Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS If you would like to reduce the costs incurred by our company in mailing proxy materials, you can consent to receiving all future proxy statements, proxy cards and annual reports electronically via e-mail or the Internet. To sign up for electronic delivery, please follow the instructions above to vote using the Internet and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years. VOTE BY PHONE - 1-800-XXX-XXXX Use any touch-tone telephone to transmit your voting instructions up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.



The Board of Directors recommends you vote FOR proposal 1 and FOR proposal 2.
		For	Against	Abstain
1.	Approval of the issuance of the shares of common stock, par value $0.001 per share, of Tecogen Inc. (“Tecogen”) to American DG Energy Inc. (“ADGE”) stockholders as contemplated by 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 ADGE, Tecogen and Tecogen.ADGE Acquisition Corp., a Delaware corporation formed for the purpose of effecting the merger and a wholly-owned subsidiary of Tecogen (“Merger Sub”).	¨	¨	¨

2.	Approval to adjourn or postpone the special meeting, if necessary or appropriate, to solicit additional proxies.	¨	¨	¨

Note: Such other business may properly come before the meeting or any adjournment thereof.



		Yes	No
Please indicate if you plan to attend this meeting		¨	¨

Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name, by authorized officer.


Signature [PLEASE SIGN WITHIN BOX]	Date			Signature Joint Owners	Date

The undersigned hereby constitutes and appoints John N. Hatsopoulos, Benjamin Locke, David Garrison, and Angelina Galiteva, or any one of them (with full power to act alone), as Proxies of the undersigned, with full power of substitution, to vote all of the common stock of Tecogen Inc which the undersigned has the full power to vote at the Annual Meeting of stockholders of Tecogen Inc to be held at Tecogen Inc, 45 First Ave, Waltham, MA 02451, on [*] at [*], and at any adjournments thereof, in the transaction of any business which may come before said meeting, with all the powers the undersigned would possess if personally present and particularly to vote each matter set forth on the reverse side, all as in accordance with the Notice of Special Meeting and Proxy Statement furnished with this Proxy.

Unless otherwise specified by the undersigned, this proxy will be voted FOR Proposal 1, and FOR Proposal 2 and also will be voted by the proxy holders at their discretion as to any other matters properly transacted at the Special Meeting or any postponement or adjournment thereof.