<SEC-DOCUMENT>0001537435-25-000088.txt : 20250717
<SEC-HEADER>0001537435-25-000088.hdr.sgml : 20250717
<ACCEPTANCE-DATETIME>20250717214400
ACCESSION NUMBER:		0001537435-25-000088
CONFORMED SUBMISSION TYPE:	S-1MEF
PUBLIC DOCUMENT COUNT:		4
<REFERENCE-462B>333-288668
FILED AS OF DATE:		20250717
DATE AS OF CHANGE:		20250717
EFFECTIVENESS DATE:		20250717

FILER:

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TECOGEN INC.
		CENTRAL INDEX KEY:			0001537435
		STANDARD INDUSTRIAL CLASSIFICATION:	AIR COND & WARM AIR HEATING EQUIP & COMM & INDL REFRIG EQUIP [3585]
		ORGANIZATION NAME:           	06 Technology
		EIN:				043536131
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		S-1MEF
		SEC ACT:		1933 Act
		SEC FILE NUMBER:	333-288740
		FILM NUMBER:		251132537

	BUSINESS ADDRESS:	
		STREET 1:		76 TREBLE COVE ROAD
		STREET 2:		BLDG. 1
		CITY:			NORTH BILLERICA
		STATE:			MA
		ZIP:			01862
		BUSINESS PHONE:		781-466-6400

	MAIL ADDRESS:	
		STREET 1:		76 TREBLE COVE ROAD
		STREET 2:		BLDG. 1
		CITY:			NORTH BILLERICA
		STATE:			MA
		ZIP:			01862

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TECOGEN INC
		DATE OF NAME CHANGE:	20111215
</SEC-HEADER>
<DOCUMENT>
<TYPE>S-1MEF
<SEQUENCE>1
<FILENAME>tecogenforms-1mef.htm
<DESCRIPTION>S-1MEF
<TEXT>
<html><head>
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<title>Document</title></head><body><div id="ib9671aa2b3664a13b4176afc2a66417b_1"></div><div style="min-height:72pt;width:100%"><div><font><br></font></div></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">As filed with the United States Securities and Exchange Commission on&#160;July 18, 2025.</font></div><div style="text-align:justify"><font><br></font></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="border-bottom:1.5pt solid #000000;padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">Registration No. 333-______</font></td></tr></table></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font><br></font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">UNITED STATES</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">SECURITIES AND EXCHANGE COMMISSION</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">WASHINGTON, D.C.  20549</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:700;line-height:120%">_______________</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font><br></font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">FORM S-1</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">REGISTRATION STATEMENT</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">UNDER</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">THE SECURITIES ACT OF 1933</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font><br></font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%;text-decoration:underline">TECOGEN INC.</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(Exact name of registrant as specified in its charter)</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center"><font><br></font></div><div style="padding-left:2.25pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:99.519%"><tr><td style="width:1.0%"></td><td style="width:32.233%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:32.233%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:32.234%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">Delaware</font></div><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(State or other jurisdiction of incorporation or organization)</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">3585</font></div><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(Primary Standard Industrial</font></div><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Classification Code Number)</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">04-3536131</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(IRS Employer</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Identification Number)</font></div></td></tr></table></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">76 Treble Cove Road</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Building 1</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">North Billerica, MA 01862</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">781.466.6400</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center;text-indent:4.8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(Address, including zip code, and telephone number, including area code, </font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center;text-indent:4.8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">of the registrant&#8217;s principal executive offices)</font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center;text-indent:4.8pt"><font><br></font></div><div style="padding-left:76.25pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:67.307%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">John K. Whiting, IV, Esq.</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">General Counsel</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Tecogen Inc.</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">76 Treble Cove Road</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Building 1</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">North Billerica, Massachusetts 01862</font></div><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">Telephone&#58; 781.466.6016</font></div><div style="padding-left:9.74pt;padding-right:9.74pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(Name, address, including zip code, and telephone number, including area code, of agent for service)</font></div></td></tr></table></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center;text-indent:4.8pt"><font><br></font></div><div style="padding-left:8.1pt;padding-right:8.1pt;text-align:center;text-indent:4.8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">Copies of Communications to&#58;</font></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:48.820%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:48.980%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Neil R.E. Carr, Esq.</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Somertons, PLLC</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">1025 Connecticut Avenue, N.W.</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Suite 1000</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Washington, D.C.  20036</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Telephone&#58; 202.459.4651</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">M. Ali Panjwani, Esq.</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Pryor Cashman LLP</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">7 Times Square</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">40</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:5.85pt;font-weight:700;line-height:120%;position:relative;top:-3.15pt;vertical-align:baseline">th</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%"> Floor</font></div><div style="padding-left:10.87pt;padding-right:10.87pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">New York, NY  10035</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Telephone&#58; 212.326.0820</font></div></td></tr></table></div><div style="padding-right:13.95pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Approximate date of commencement of proposed sale to the public&#58; </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">As soon as practicable after this registration statement becomes effective. </font></div><div style="padding-right:13.95pt;text-align:justify"><font><br></font></div><div style="padding-right:13.95pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font></div><div style="padding-right:13.95pt;text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  &#160;</font><font style="background-color:#ffffff;color:#000000;font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"> </font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(File No. 333-288668)</font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div><font><br></font></div></div><div style="padding-right:13.95pt;text-align:justify"><font><br></font></div><div style="padding-right:13.95pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  &#160;</font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font></div><div style="padding-right:13.95pt;text-align:justify"><font><br></font></div><div style="padding-right:13.95pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering&#58; </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font></div><div><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company.  See the definitions of &#8220;large accelerated filer,&#8221; &#8220;accelerated filer,&#8221; &#8220;smaller reporting company,&#8221; and &#8220;emerging growth company&#8221; in Rule 12b-2 of the Exchange Act.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Large accelerated filer </font><font style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:9pt;font-weight:400;line-height:120%">&#9744;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Accelerated filer </font><font style="background-color:#ffffff;color:#000000;font-family:'Arial',sans-serif;font-size:9pt;font-weight:400;line-height:120%">&#9744;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Non-accelerated filer </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font><font style="color:#000000;font-family:'Courier New',monospace;font-size:9pt;font-weight:400;line-height:120%"> </font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Smaller reporting company </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font><font style="color:#000000;font-family:'Courier New',monospace;font-size:9pt;font-weight:400;line-height:120%"> &#160;&#160;&#160;&#160;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Emerging growth company </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%"> </font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  </font><font style="font-family:'Wingdings',sans-serif;font-size:9pt;font-weight:400;line-height:120%"></font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">________________________________________________________________________________________________________</font></div><div><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">The Registration Statement shall become effective upon filing with the Commission pursuant to Rule 462(b) under the Securities Act of 1933, as amended.</font></div><div style="text-align:justify"><font><br></font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font><br></font></div></div></div><div id="ib9671aa2b3664a13b4176afc2a66417b_4"></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div><font><br></font></div></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">EXPLANATORY NOTE AND </font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">INCORPORATION OF CERTAIN INFORMATION BY REFERENCE</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">This Registration Statement on Form S-1 </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Registration Statement&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%"> of Tecogen Inc, a Delaware corporation </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Company&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, is being filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Securities Act&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, for the sole purpose of increasing the aggregate number of shares of common stock, $.001 par value per share </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;common stock&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, offered by the Company by 918,333 shares, of which 85,000 are subject to purchase upon exercise of the underwriters&#8217; option to purchase additional shares of the Company&#8217;s common stock. The contents of the Registration Statement on Form S-1, as amended (File No. 333-288668), initially filed by the Company with the Securities and Exchange Commission </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;SEC&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%"> pursuant to the Securities Act on July 15, 2025 (as amended, </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">&#8220;Initial Registration Statement&#8221;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">), and which was declared effective by the SEC on July 17, 2025, including all exhibit thereto, are incorporated by reference into this Registration Statement.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">The additional shares of common stock that are being registered for sale hereby are in an amount and at a price that together represents no more than 20% of the maximum aggregate offering price set forth in the Calculation of Filing Fee Table filed as Exhibit 107.1 to the Initial Registration Statement.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">The required opinion and consents are listed in Part II, Item 16 of this Registration Statement and filed herewith or incorporated herein by reference.</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">PART II</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">Information Not Required in Prospectus</font></div><div style="text-align:center"><font><br></font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">Item 16. Exhibits and Financial Statement Schedules.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">The following documents are filed as exhibits to this registration statement, and all other exhibits previously filed as exhibits to the registrant&#8217;s Registration Statement on Form S-1 (File No. 333-288668), are incorporated by reference into, and shall be deemed to be a part of this filing.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">EXHIBIT INDEX</font></div><div style="text-align:justify"><font><br></font></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:3.131%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:3.131%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:90.438%"></td><td style="width:0.1%"></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:0.37pt;padding-right:0.37pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%">Exhibit </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:120%;text-decoration:underline">Number</font></div></td><td colspan="3" style="padding:2px 1.18pt;text-align:center;vertical-align:bottom"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:700;line-height:100%;text-decoration:underline">Description</font></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">5.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:10.77pt;padding-right:-2.13pt;text-align:justify"><font style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="somertonslegalopinionforms.htm" style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline">&#160;Legal Opinion of Somertons, PLLC, filed herewith.</a></font></div></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">23.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:10.77pt;padding-right:-2.13pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:120%">&#160;</font><font style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="consentofwolfcompany.htm" style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline">Consent of Wolf &#38; Company, P.C.</a><a href="consentofwolfcompany.htm" style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline">, filed herewith.</a></font></div></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">23.2</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:10.77pt;padding-right:-2.13pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">&#160;Consent of Somertons, PLLC (included in Exhibit 5.1 hereto). </font></div></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">24.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:10.77pt;padding-right:-2.13pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">&#160;Power of Attorney of certain directors and officers of the Registrant. *</font></div></td></tr><tr><td colspan="6" style="padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">107.1</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:10.77pt;padding-right:-2.13pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">&#160;</font><font style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline"><a href="tecogencalculationoffiling.htm" style="color:#0000ff;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;text-decoration:underline">Filing Fee Table, filed herewith.</a></font></div></td></tr><tr style="height:9pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:0 1pt"></td></tr><tr><td colspan="3" style="padding:2px 1.37pt 2px 1pt;text-align:right;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:100%">*</font></td><td colspan="6" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="margin-bottom:2pt;margin-top:2pt;padding-left:11.07pt;padding-right:-2.13pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">Previously filed on the signature page to the Registrant&#8217;s Registration Statement on Form S-1, as amended (File No. 333-288668) originally filed with the Securities and Exchange Commission on July 15, 2025.</font></div></td></tr></table></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font><br></font></div><div style="text-align:center"><font><br></font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div style="text-align:center"><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:72pt;width:100%"><div><font><br></font></div></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">SIGNATURES</font></div><div><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Pursuant to the requirements of the Securities Act of 1933, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Town of North Billerica, Commonwealth of Massachusetts, on July 18, 2025.</font></div><div style="text-align:justify"><font><br></font></div><div style="padding-left:229.5pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:51.121%"><tr><td style="width:1.0%"></td><td style="width:6.736%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:91.064%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">TECOGEN INC.</font></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">By&#58; </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%;text-decoration:underline">&#47;s&#47; Abinand Rangesh</font></div><div style="padding-left:19.57pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Abinand Rangesh</font></div><div style="padding-left:19.57pt;padding-right:2.77pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Chief Executive Officer and Chief </font></div><div style="padding-left:19.57pt;padding-right:2.77pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Financial Officer (</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Principal Executive Officer and Principal Financial Officer)</font></div></td></tr></table></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.</font></div><div style="text-align:justify"><font><br></font></div><div style="padding-left:23.4pt"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:95.032%"><tr><td style="width:1.0%"></td><td style="width:38.191%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:38.360%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:20.149%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%;text-decoration:underline">Signature</font></td><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%;text-decoration:underline">Title</font></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:middle"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%;text-decoration:underline">Date</font></div></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%;text-decoration:underline">&#47;s&#47; Abinand Rangesh</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Abinand Rangesh</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:middle"><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Chief Executive Officer, Chief Financial Officer, and Director (</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Principal Executive Officer and Principal Financial Officer)</font></div></td><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font 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Deschenes</font></div><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Roger P. Deschenes</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:middle"><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Chief Accounting Officer </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(Principal Accounting Officer)</font></div></td><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:15pt"><td colspan="3" style="padding:0 3.77pt 0 1pt"></td><td colspan="3" rowspan="3" style="padding:2px 1pt 2px 3.77pt;text-align:left;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Director and Chairperson</font></td><td colspan="3" rowspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:14pt"><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">*</font></td></tr><tr style="height:21pt"><td colspan="3" style="border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Angelina M. Galiteva</font></div></td></tr><tr style="height:21pt"><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">*</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Lead Director</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:21pt"><td colspan="3" style="border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">John N. Hatsopoulos</font></div></td></tr><tr style="height:21pt"><td colspan="3" style="padding:0 1pt"></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Director</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:21pt"><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Ahmed F. Ghoniem</font></div></td></tr><tr style="height:21pt"><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">*</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Director</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:21pt"><td colspan="3" style="border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Earl R. Lewis, III</font></div></td></tr><tr style="height:21pt"><td colspan="3" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">*</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Director</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:21pt"><td colspan="3" style="border-top:0.5pt solid #000000;padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Susan F. Hirsch</font></td></tr><tr style="height:21pt"><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:middle"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">*</font></div></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:justify;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">Director</font></td><td colspan="3" rowspan="2" style="padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:middle"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:100%">7&#47;18&#47;2025</font></td></tr><tr style="height:21pt"><td colspan="3" style="border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:justify"><font style="background-color:#ffffff;color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">John M. Albertine</font></div></td></tr></table></div><div style="text-align:justify"><font><br></font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">*&#160;&#160;&#160;&#160;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">By&#58; &#47;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%;text-decoration:underline">s&#47; John K. Whiting, IV</font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;John K. Whiting, IV</font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;Attorney-in-Fact</font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:12.00pt">II-2</font></div><div style="text-align:justify"><font><br></font></div></div></div></body></html>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-FILING FEES
<SEQUENCE>2
<FILENAME>tecogencalculationoffiling.htm
<DESCRIPTION>EX-FILING FEES
<TEXT>
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<title>Document</title></head><body><div id="i4d436107c8244955985a56711ac60d53_1"></div><div style="min-height:57.6pt;width:100%"><div><font><br></font></div></div><div style="text-align:right"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">Exhibit 107.1</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">Calculation of Filing Fee Table</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:11pt;font-weight:700;line-height:120%;text-decoration:underline">Form S-1</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">(Form Type)</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:11pt;font-weight:700;line-height:120%;text-decoration:underline">Tecogen Inc.</font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">(Exact Name of Registrant as Specified in its Charter)</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%;text-decoration:underline">Table 1&#58; Newly Registered and Carry Forward Securities</font></div><div style="text-align:center"><font><br></font></div><div style="text-align:center"><font><br></font></div><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:7.137%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.321%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.365%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:6.512%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.677%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:7.346%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.217%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:6.303%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.217%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:7.763%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.156%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:6.512%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.321%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.365%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.886%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:5.886%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:8.916%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Security</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Type</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Security Class</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Title</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Fee Calculation or Carry Forward Rule</font></div></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Amount Registered </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:120%">(1)</font></div></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Proposed Maximum Aggregate Offering Price Per Share </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:120%">(2)</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Maximum Aggregate Offering Price </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:120%">(2)</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Fee Rate</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Amount of Registration Fee </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:120%">(3)</font></div></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Carry Forward Form Type</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Carry Forward File Number</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">Carry Forward Initial Effective Date</font></div></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Filing Fee Previously Paid In Connection with Unsold Securities to be Carried Forward</font></td></tr><tr><td colspan="51" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:120%">Newly Registered Securities </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:120%">(1)</font></div></td></tr><tr><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt 2px 3.77pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Fees to be paid</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Equity</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Common stock, $.001 par value per share</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Rule 457(a)</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">918,333 </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:100%">(1)</font></div></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">$5.00</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:120%">$4,591,665.00</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">0.0001531</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">$702.98 </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:6pt;font-weight:400;line-height:100%">(3)</font></div></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td></tr><tr><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt 2px 3.77pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Fees previously paid</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:100%">-</font></td></tr><tr><td colspan="51" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font><br></font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:120%">Carried Forward Securities</font></div></td></tr><tr><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt 2px 3.77pt;text-align:left;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">Carried Forward Securities</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">-</font></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td></tr><tr><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="18" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">Total Offering Amounts</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">$4,591,665.00</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">0.0001531</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">$702.98</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td></tr><tr><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="18" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">Total Fee Previously Paid</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">-</font></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">-</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td></tr><tr><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="18" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 3.77pt 2px 1pt;text-align:right;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:700;line-height:100%">Net Fee Due</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:2px 2.38pt;text-align:center;vertical-align:top"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:8pt;font-weight:400;line-height:100%">$702.98</font></td><td colspan="6" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td><td colspan="3" style="border-bottom:0.5pt solid #000000;border-left:0.5pt solid #000000;border-right:0.5pt solid #000000;border-top:0.5pt solid #000000;padding:0 1pt"></td></tr></table></div><div style="text-align:center"><font><br></font></div><div style="padding-left:18pt"><font><br></font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(1)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;padding-left:7.52pt">Represents only the additional number of shares being registered pursuant to this Registration Statement on Form S-1, including 85,000 additional shares subject to purchase upon exercise of the option granted to the underwriters. Does not include the shares that were previously registered in the Registration Statement on Form S-1 (File No. 333-288668) (as amended, &#8220;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">Initial Registration Statement&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%"> which was declared effective by the Securities and Exchange Commission on July 17, 2025.  Pursuant to Rule 416 under the Securities Act of 1933, as amended </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Securities Act&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">, this Registration Statement shall be deemed to cover any additional shares of common stock, $.001 par value per share </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;common stock&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">, of Tecogen Inc., a Delaware corporation </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Tecogen&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">, as may be offered or issued from time to time upon stock splits, stock dividends, recapitalizations or similar transactions. </font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(2)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;padding-left:7.52pt">Based upon the public offering price.</font></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%">(3)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:9pt;font-weight:400;line-height:120%;padding-left:7.52pt">The amount of the registration fee is calculated in accordance with Rule 457(a) under the Securities Act.  Tecogen previously registered 3,066,667 shares of common stock (including 400,000 shares issuable pursuant to the underwriters&#8217; over-allotment option) with an aggregate offering price of $23,000,003 on the Initial Registration Statement. In accordance with Rule 462(b) under the Securities Act, an additional amount of securities having a maximum aggregate offering price of $4,591,665 is hereby registered.</font></div><div style="height:48.6pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div></body></html>
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<DOCUMENT>
<TYPE>EX-5.1
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<FILENAME>somertonslegalopinionforms.htm
<DESCRIPTION>EX-5.1
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<title>Document</title></head><body><div id="i087e78bee5a34b028436399f6a3ec1f4_1"></div><div style="min-height:126.72pt;width:100%"><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:97.222%"><tr><td style="width:1.0%"></td><td style="width:48.900%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:48.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:24pt;font-weight:700;line-height:120%">S</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:22pt;font-weight:700;line-height:120%">omertons,</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:36pt;font-weight:700;line-height:120%"> </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:16pt;font-weight:700;line-height:120%">pllc</font></div><div style="padding-left:2.77pt;padding-right:2.77pt"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:12pt;font-weight:400;line-height:120%">Attorneys at law</font></div></td><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">1025 Connecticut Avenue, N.W.</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Suite 1000 </font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Washington, D.C.  20036</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Tel&#58; 202.459.4651</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Fax&#58; 202.478.2980</font></div><div style="padding-left:2.77pt;padding-right:2.77pt;text-align:right"><font style="color:#000000;font-family:'Arial Narrow',sans-serif;font-size:10pt;font-weight:400;line-height:120%">www.somertons.com</font></div></td></tr></table></div><div><font><br></font></div></div><div style="margin-bottom:6pt;text-align:right"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%;text-decoration:underline">EXHIBIT 5.1</font></div><div style="margin-bottom:6pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">July 18, 2025</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">The Board of Directors</font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Tecogen Inc.</font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">76 Treble Cove Road</font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Building 1</font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">North Billerica, Massachusetts 01862</font></div><div><font><br></font></div><div style="text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%">Re&#58;&#160;&#160;&#160;&#160;Tecogen Inc.</font></div><div style="padding-left:36pt;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:700;line-height:120%;text-decoration:underline">Securities Registered under Registration Statement on Form S-1</font></div><div><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Ladies and Gentlemen&#58;</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">We have acted as special securities counsel to Tecogen Inc., a Delaware corporation </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Company&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, in connection with (i) the Registration Statement on Form&#160;S-1&#160;under the Securities Act of 1933, as amended </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Securities Act&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, filed by the Company with the Securities and Exchange Commission </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;SEC&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%"> on July&#160;15, 2025, ss amended on July 16, 2025 </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Initial Registration Statement&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, and (ii) a second Registration Statement on Form S-1 filed pursuant to Rule 462(b) under the Securities Act </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;462(b) Registration Statement,&#8221;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%"> and together with the Initial Registration Statement, the </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">&#8220;Registration Statement&#8221;</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">). This opinion is being furnished to you in connection with your filing of the 462(b) Registration Statement relating to the registration by the Company of up to 918,333 additional shares </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Shares&#8221;) </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">of the Company&#8217;s common stock, $.001 par value per share </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;common stock&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, including 85,000 shares of common stock purchasable by the underwriters upon their exercise of an over-allotment option granted to the underwriters by the Company.  The Shares are being offered and sold pursuant to an underwriting agreement (in substantially the form filed as an Exhibit 1.1 to the Initial Registration Statement) to be entered into by and between the Company and Roth Capital Partners, LLC, as sole underwriter and manager of the offering </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Underwriting Agreement&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">. </font></div><div style="text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation&#160;S-K&#160;under the Securities Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or the 462(b) Registration Statement, other than as expressly stated herein with respect to the issue of the Shares.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">We have examined originals of copies of the Company&#8217;s Amended and Restated Certificate of Incorporation, Amended and Restated Bylaws, the Registration Statement, the preliminary prospectus included therein </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">(&#8220;Prospectus&#8221;)</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">, the 462(b) Registration Statement, the form of Underwriting Agreement, minutes of various meetings and consents of the Board of Directors of the Company, originals or copies of all such records of the Company, agreements, certificates of public officials, certificates of officers and representatives of the Company and others, and such other documents, certificates, records, authorizations, proceedings, statutes and judicial decisions as we have deemed necessary to form the basis of the opinions expressed herein.  As to various questions of fact material to our opinion, we have relied upon statements and certificates of officers and representatives of the Company and others.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">In such examination, we have assumed the genuineness and authenticity of all signatures on original documents&#59; the authenticity of all documents submitted to us as originals&#59; the conformity to originals of all documents submitted to us as copies or specimens&#59;&#160;the authenticity of the originals of such documents, agreements and instruments submitted to us as copies or specimens&#59; the conformity of the text of each documents filed with the SEC through the SEC&#8217;s Electronic Data Gathering, Analysis and Retrieval System to the printed document reviewed by us&#59; the accuracy, completeness and authenticity of certificates of public officials&#59; the due authorization, execution and delivery of all documents where authorization, execution and delivery are prerequisites to the effectiveness of such documents&#59; that the Initial Registration Statement and the 462(b) Registration Statement have become effective under the Securities Act, the Prospectus, the final prospectus, and any and all free-writing prospectus(es) related to the offer and sale of the Shares have been delivered and </font></div><div style="height:57.6pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div><hr style="page-break-after:always"><div style="min-height:126.72pt;width:100%"><div><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:95.561%"><tr><td style="width:1.0%"></td><td style="width:98.900%"></td><td style="width:0.1%"></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:top"><div style="padding-right:2.77pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:18pt;font-weight:400;line-height:120%">Somertons</font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:16pt;font-weight:400;line-height:120%">, </font><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:120%">pllc</font></div></td></tr></table></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">The Board of Directors</font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Tecogen Inc.</font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">July 18, 2025</font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Page &#124; 2</font></div><div><font><br></font></div></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">filed as required by such laws&#59; that the issuance and sale of the Shares does not violate any applicable law, are in conformity with the Company&#8217;s then operative charter and bylaws, does not result in a default under or breach of any agreement or instrument binding upon the Company and comply with any applicable requirement or restriction imposed by any court or governmental body having jurisdiction over the Company or its properties or assets&#59; &#160;the Prospectus included in the Registration Statement contains or incorporates by reference therein all information and disclosures required by applicable SEC rules and forms&#59; the Underwriting Agreement with respect to the Shares offered will have been duly authorized and validly executed and delivered by the Company and the other parties thereto&#59; and the Shares to be sold to the underwriters by the Company will be sold at a price established by the board of directors of the Company or a duly authorized committee thereof.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">In connection with the preparation of this opinion, we have reviewed such questions of law as we deemed necessary. We do not herein give any opinion with respect to the laws of any jurisdiction other than the laws of the District of Columbia, the general laws of the United States of America, Federal securities laws and Delaware corporations law (including the statutory provisions, all applicable provisions of the Delaware constitution and reported judicial decisions interpreting the foregoing), all as in effect on the date of this opinion.  We are not rendering any opinion as to compliance with any Federal or state law, rule or regulation relating to securities, including but not limited to, state &#8220;blue sky&#8221; laws, or to the sale or issuance thereof. Our opinion expressed below is subject to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and other similar laws of general application affecting the rights and remedies of creditors and to general principles of equity.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Based upon the foregoing, we are of the opinion that the Shares have been duly authorized by the Company and, when issued and delivered by the Company against payment therefor in accordance with the terms of and in the manner contemplated by the Underwriting Agreement, the Registration Statement, and Prospectus, will be validly issued, fully paid and nonassessable.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:31.5pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">We hereby consent to the inclusion of this opinion as Exhibit 5.1 to the 462(b) Registration Statement and to the references in the Initial Registration Statement, Prospectus, and in the final prospectus for the offering to this firm as attorneys who have passed upon legal matters in connection with the offering of the securities described therein under the caption &#8220;Legal Matters.&#8221;  In giving such consent, we do not believe that we are &#8220;experts&#8221; within the meaning of such term as used in the Securities Act or the rules&#160;and regulations of the SEC issued thereunder with respect to any part of the 462(b) Registration Statement, including this opinion as an exhibit or otherwise.</font></div><div style="text-align:justify;text-indent:36pt"><font><br></font></div><div style="text-align:justify;text-indent:36pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">This opinion is expressed as of the date hereof unless otherwise expressly stated, and we disclaim any undertaking to advise you of any subsequent changes in the facts stated or assumed herein or of any subsequent changes in applicable laws.</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%">Very truly yours,</font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font><br></font></div><div style="text-align:justify"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:120%;text-decoration:underline">&#47;s&#47;Somertons, PLLC </font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:11pt;font-weight:700;line-height:120%">Somertons, pllc</font></div><div style="height:57.6pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div><font><br></font></div></div></div></body></html>
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<DOCUMENT>
<TYPE>EX-23.1
<SEQUENCE>4
<FILENAME>consentofwolfcompany.htm
<DESCRIPTION>EX-23.1
<TEXT>
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<title>Document</title></head><body><div id="i937600ef63ca4cf6b1d4358de4506e1e_1"></div><div style="min-height:72pt;width:100%"><div style="margin-bottom:8pt"><font><br></font></div></div><div style="margin-bottom:8pt;text-align:right"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">EXHIBIT 23.1</font></div><div style="margin-bottom:8pt;text-align:center"><font><br></font></div><div style="margin-bottom:8pt;text-align:center"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:700;line-height:134%">Consent of Independent Registered Public Accounting Firm</font></div><div style="margin-bottom:8pt"><font><br></font></div><div style="margin-bottom:8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">We consent to the incorporation by reference in this Registration Statement on Form S-1 and related Prospectus of Tecogen Inc. filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended, of our report dated March 18, 2025, relating to the consolidated financial statements of Tecogen Inc. appearing in the Annual Report on Form 10-K of Tecogen Inc. for the years ended December 31, 2024 and December 31, 2023, incorporated by reference in Registration Statement (No. 333-288-668) on Form S-1, as amended, declared effective on July 17, 2025.</font></div><div style="margin-bottom:8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">We also consent to the reference to our firm under the heading &#8220;Experts&#8221; in such Prospectus.</font></div><div style="margin-bottom:8pt"><font><br></font></div><div style="margin-bottom:8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-style:italic;font-weight:400;line-height:134%;text-decoration:underline">&#47;s&#47; Wolf &#38; Company, P.C.</font></div><div style="margin-bottom:8pt"><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">Wolf &#38; Company, P.C.</font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">Boston, Massachusetts</font></div><div><font style="color:#000000;font-family:'Times New Roman',serif;font-size:12pt;font-weight:400;line-height:134%">July 17, 2025</font></div><div style="margin-bottom:8pt"><font><br></font></div><div style="height:72pt;position:relative;width:100%"><div style="bottom:0;position:absolute;width:100%"><div style="margin-bottom:8pt"><font><br></font></div></div></div></body></html>
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