<SEC-DOCUMENT>0001104659-20-024086.txt : 20200224
<SEC-HEADER>0001104659-20-024086.hdr.sgml : 20200224
<ACCEPTANCE-DATETIME>20200224074429
ACCESSION NUMBER:		0001104659-20-024086
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200218
FILED AS OF DATE:		20200224
DATE AS OF CHANGE:		20200224

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Conway Gerard L JR
		CENTRAL INDEX KEY:			0001308706

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34392
		FILM NUMBER:		20642077

	MAIL ADDRESS:	
		STREET 1:		968 ALBANY-SHAKER ROAD
		CITY:			LATHAM
		STATE:			NY
		ZIP:			12110

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PLUG POWER INC
		CENTRAL INDEX KEY:			0001093691
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRICAL INDUSTRIAL APPARATUS [3620]
		IRS NUMBER:				223672377
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		968 ALBANY-SHAKER ROAD
		CITY:			LATHAM
		STATE:			NY
		ZIP:			12110
		BUSINESS PHONE:		5187827700

	MAIL ADDRESS:	
		STREET 1:		968 ALBANY-SHAKER ROAD
		CITY:			LATHAM
		STATE:			NY
		ZIP:			12110
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
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    <periodOfReport>2020-02-18</periodOfReport>

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        <issuerCik>0001093691</issuerCik>
        <issuerName>PLUG POWER INC</issuerName>
        <issuerTradingSymbol>PLUG</issuerTradingSymbol>
    </issuer>

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            <rptOwnerName>Conway Gerard L JR</rptOwnerName>
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            <rptOwnerStreet1>C/O PLUG POWER INC.</rptOwnerStreet1>
            <rptOwnerStreet2>968 ALBANY SHAKER ROAD</rptOwnerStreet2>
            <rptOwnerCity>LATHAM</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>12110</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Gen. Counsel,Corp.Sec.,Sr. VP</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Plug Power Common Stock</value>
            </securityTitle>
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            <transactionTimeliness>
                <value></value>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
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                <sharesOwnedFollowingTransaction>
                    <value>413829</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Plug Power Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-02-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
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            <transactionTimeliness>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeTransaction>
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            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.14</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-02-18</value>
            </transactionDate>
            <transactionCoding>
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            <transactionTimeliness>
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            </transactionTimeliness>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
                <value>2027-08-31</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>49133</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>275867</value>
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            </transactionDate>
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                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
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            <exerciseDate>
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            <expirationDate>
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                </underlyingSecurityTitle>
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                <transactionCode>M</transactionCode>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
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                <value>2025-07-23</value>
                <footnoteId id="F6"/>
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                </underlyingSecurityTitle>
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                    <value>D</value>
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        </derivativeTransaction>
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                <value>Stock Option (right to buy)</value>
            </securityTitle>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>167534</value>
                </transactionShares>
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                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-08-31</value>
            </expirationDate>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>167534</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>108333</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares sold pursuant to a pre-established 10b5-1 trading plan.</footnote>
        <footnote id="F2">The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.00 to $5.26, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.</footnote>
        <footnote id="F3">On August 31, 2017, the Reporting Person was granted 325,000 stock options, vesting in three substantially equal annual installments beginning on the first anniversary of the grant date.</footnote>
        <footnote id="F4">On August 28, 2018, the Reporting Person was granted 200,000 stock options, vesting in three substantially equal annual installments beginning on the first anniversary of the grant date.</footnote>
        <footnote id="F5">The stock option granted to the reporting person is fully vested and exercisable as of the date hereof.</footnote>
        <footnote id="F6">The Form 5 filed on February 16, 2016 included an incorrect expiration date (07/23/2015) and an incorrect number of securities beneficially owned (649,949).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Gerard L. Conway, Jr.</signatureName>
        <signatureDate>2020-02-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
