<SEC-DOCUMENT>0001537435-20-000034.txt : 20200421
<SEC-HEADER>0001537435-20-000034.hdr.sgml : 20200421
<ACCEPTANCE-DATETIME>20200421192319
ACCESSION NUMBER:		0001537435-20-000034
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20200421
FILED AS OF DATE:		20200421
DATE AS OF CHANGE:		20200421

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Benjamin Locke M.
		CENTRAL INDEX KEY:			0001625781

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36103
		FILM NUMBER:		20806298

	MAIL ADDRESS:	
		STREET 1:		45 FIRST AVE
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

ISSUER:		

	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]
		IRS NUMBER:				043536131
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		45 FIRST AVENUE
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		781-466-6400

	MAIL ADDRESS:	
		STREET 1:		45 FIRST AVENUE
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	TECOGEN INC
		DATE OF NAME CHANGE:	20111215
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_158751138142075.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-04-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001537435</issuerCik>
        <issuerName>TECOGEN INC.</issuerName>
        <issuerTradingSymbol>TGEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001625781</rptOwnerCik>
            <rptOwnerName>Benjamin Locke M.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>45 FIRST AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02451</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-04-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.02</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5418</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>SEP-IRA</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Bonnie Brown, attorney-in-fact</signatureName>
        <signatureDate>2020-04-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>locke_poatgen.htm
<DESCRIPTION>POWER OF ATTORNEY
<TEXT>
<!-- Document created using Workiva -->
<html>
<body>
<pre>
POWER OF ATORNEY

Know All Men By These Presents, that the undersigned hereby constitutes
and appoints David Garrison, the undersigned's true and lawful attorney-in-fact to:

(1)    execute for and on behalf of the undersigned, in the undersigned's
capacity as an officer and/or director of Tecogen Inc. (the "Company"), Forms 3, 4, 5,
or Form ID in accordance with Section 16 of the Securities Exchange Act of 1934 and the
rules thereunder ("Section 16");

(2)    do and perform any and all acts for and on behalf of the undersigned which may
be necessary or desirable to complete and execute any such Form 3, 4, 5, or Form ID complete
and execute any amendment or amendments  thereto, and timely file such form or forms with the
United Sates Securities and Exchange Commission and any stock exchange or similar authority; and

(3)    take any other action of any type whatsoever in connection with the foregoing that, in
the opinion of such attorney-in-fact, may be of benefit to, in the best interest of, or legally
required by, the undersigned, it being understood that the documents executed by such attorney-in-fact
on behalf of the undersigned  pursuant to this Power of Attorney shall be in such form and shall contain
such terms and conditions as such attorney-in-fact  may approve in such attorney-in -fact's  discretion.

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any
and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of
the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or revocation, hereby ratifying and
confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted.
The undersigned acknowledges that the foregoing attorney-in-fact, in serving in such capacity at the request
of the undersigned, is not assuming, nor is the Company assuming, any of the undersigned's responsibilities
to comply with Section 16.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer required
to file Forms 3, 4, 5, and Form ID with respect to the undersigned's holdings of and transactions in securities
issued by the Company, unless earlier revoked by the undersigned in a signed writing delivered to the foregoing
attorneys-in-fact.

In WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of this 17th day of
November, 2014.

/s/ Benjamin Locke
Benjamin M. Locke
Co-CEO
</pre>
</body>
</html>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
