SecProbe.io

February 13, 2017

Mr. John N. Hatsopoulos
Co-Chief Executive Officer
Tecogen Inc.
45 First Avenue
Waltham, MA 02451

Re: Tecogen Inc.
Amendment No. 1 to Registration Statement on Form S -4
Filed January 30, 2017
  File No. 333-215231

Dear Mr. Hatsopoulos :

We have reviewed your amended registration statement  and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.

Please respond to this letter by amending your registration statement and providing the
requested information .  If you do not believe our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.

After reviewin g any amendment to your registration statement and the information you
provide in response to these  comments, we may have  additional comments.   Unless we note
otherwise, our references to prior comments are to comments in our January 17, 2017 letter.

Stock Ownership of Directors and Executive Officers of Tecogen, page 6
Stock Ownership of Directors and Executive Officers of ADGE, page 6

1. We note in response to comment 2 of our letter dated January 17, 2017, you have
removed references to George Hatsopoulos .   Given the initial disclosure about his share
ownership and the reference to him in the opinion of your financial advisor, please
disclose his affiliation with the company.  In addition, if Mr. Hatsopoulos has interests in
the merger that are different from other shareholders, as the opinion of the financial
advisor suggests, please disclose those interests.

John N. Hatsopoulos
Tecogen, Inc.
February 13, 2017
Page 2

 Interests of Tecogen’s Directors and Executive Officers in the Merger, page 6
Interests of ADGE’s Directors and Executive Officers in the Merg er, page 6

2. We note in your response to comment 3 of our letter dated January 17, 2017 and we
reissue our comment.  Please disclose all material interest of director, officers, and
affiliates and quantify the interests of directors, executive officers, and  affiliates in the
summary.  You provided cross references, but you do not quantify the interests of
directors and executive officers.  Please revise this section to quantify these interests for
each person. Please ensure that you cite the correct page num ber in your cross references.

3. Please disclose the overlapping roles of any of the directors or executive officers. Please
also disclose what role the directors and executive officers will serve in the surviving
company. We note your statement that only Ch arles Maxwell and Benjamin Locke have
an interest in the Merger that is different from, or in addition to, the interests of an
ordinary Tecogen stockholder.  It appears that other directors and officers may have
interests different from an ordinary Tecogen  stockholder.  Please revise or advise.

Unaudited Pro Forma Condensed Combined Financial Information, page 11

Note 4. Fair Value Estimate of Assets to be Acquired and Liabilities to be Assumed, page 18

4. We note your response to prior comment six.  As requested, please expand your
disclosures to more fully explain how the purchase price was determined.  In this regard,
we note the significant losses incurred by ADGE and the magnitude of unfavorable
customer contracts.

Note 5.  Adjustments to Pro Forma Balance Sheet, page 18

5. In regard to the additional disclosures you provided in your response to prior comment
ten, please address the following:
 More fully explain to us and disclose the actual terms of ADGE’s customer contracts,
including pricing provisions.  It is not clear to us if the pricing provisions of the
existing customer contracts are fixed or variable.  To the extent the pricing provisions
are not fixed, it is not clear to us how you determined the difference between t he
contracts terms and current market conditions;
 Your disclosures indicate the unfavorable contract liability you recorded includes
estimated contract extensions.  More fully explain to us and disclose when and how
customer contracts can be extended.  To the extent contract extensions are not solely
within the customers’ discretion, explain to us how and why including estimated
extensions in determining an unfavorable contract liability is appropriate;
 More fully explain to us and disclose how you determin ed the discount rate you used;
 Your disclosures indicate you assume a gross profit margin of 35% based on
Tecogen’s historical gross profit margin; however it appears to us that Tecogen sells
equipment and ADGE essentially sells energy.  More fully explai n to us how and why
you determined assuming a 35% gross profit margin is appropriate; and

John N. Hatsopoulos
Tecogen, Inc.
February 13, 2017
Page 3

  More fully explain to us and disclose how you determined contracts with favorable
terms and contracts with unfavorable terms and why offsetting such contracts is
appropriate.

Background, page 37

6. In response to comment 15 of our letter dated January 17, 2017, you stated that you
added additional detail to the discussion. It doesn’t appear that those details were
reflected in your amendment.  We reissue our comment.  P lease revise this section to
describe in sufficient detail who initiated contact among the parties, identify all parties
present at the meetings, explain the material issues discussed, and the positions taken by
those involved in each meeting.

Material U .S. Federal Income Tax Consequences of the Merger, page 60

7. In light of the short form tax opinion filed as exhibit 8 to your registration statement,
please revise this section to clearly identify each material tax consequence, set forth the
opinion of cou nsel as to each identified tax item; and set forth the basis for the opinion.
If you are unable to opine on a material tax consequence, the opinion should state this
fact clearly, provide the reason for your inability to opine on a material tax consequen ce
(for example, the facts are currently unknown or the law is unclear); and discuss the
possible alternatives and risks to investors of that tax consequence.  Please see Staff
Legal Bulletin 19 for guidance.

Where you can find more information; Incorpor ation by Reference, page 70

8. We note your response to comment 18 of our letter dated January 17, 2017 that both
companies are S -3 eligible and therefore eligible to incorporate by reference; however, it
appears that the aggregate market value of shares held by non -affiliates is not at least $75
million.  Please provide your underlying analysis of eligibility for each company. Please
note that if you are not eligible to incorporate by reference, then you will need to provide
updated Executive Compensation  information for the most recent fiscal year end required
by Item 18(a)(7)(ii) of Form S -4.

Exhibit 23.5: Opinion of Cassel Salpeter & Co., LLC

9. We note the revision to this opinion now provide a consent that is limited to Amendment
1 to the S -4.  Given t hat it appears another amendment may be necessary, please update
this opinion or remove the limitation so that the consent applies to the S -4, as amended.

We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.

John N. Hatsopoulos
Tecogen, Inc.
February 13, 2017
Page 4

 Refer to Rules 460 and 461 regarding requests for acceleration .  Please allow adequate
time for us to review any amendment prior to the requested effecti ve date of the registration
statement.

You may contact Dale Welcome, Staff Accou ntant, at (202) 551 -3865,  or Anne
McConnell, Staff Accountant at (202) 551 -3709  if you have questions regarding comments on
the financial statements and re lated matters.  Please contact Kate McHale, Staff Attorney,  at
(202) 551 -3464  or me at (202) 551 - 3754 with any other questions.

Sincerely,

/s/ Asia Timmons -Pierce, for

Pamela A. Long
Assistant Director
Office of Manufacturing and
Construction