-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 K08IGVjo4EEsyFlSQ0lG12dIshmvcwlCArMwPdfc5hyGWS1EMAG1YvQcj6zhOZ7V
 pDw4Wit5ITF5Y/iIDxsMMg==

<SEC-DOCUMENT>0001182944-09-000001.txt : 20090924
<SEC-HEADER>0001182944-09-000001.hdr.sgml : 20090924
<ACCEPTANCE-DATETIME>20090924110053
ACCESSION NUMBER:		0001182944-09-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090923
FILED AS OF DATE:		20090924
DATE AS OF CHANGE:		20090924

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MOORE JOHN A
		CENTRAL INDEX KEY:			0001182944

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33886
		FILM NUMBER:		091083969

	MAIL ADDRESS:	
		STREET 1:		403 MARSH LANE
		CITY:			WILMINGTON
		STATE:			DE
		ZIP:			19807

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACORN ENERGY, INC.
		CENTRAL INDEX KEY:			0000880984
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER PROGRAMMING SERVICES [7371]
		IRS NUMBER:				222786081
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		4 WEST ROCKLAND ROAD
		CITY:			MONTCHANIN
		STATE:			DE
		ZIP:			19710
		BUSINESS PHONE:		3026561708

	MAIL ADDRESS:	
		STREET 1:		4 WEST ROCKLAND ROAD
		CITY:			MONTCHANIN
		STATE:			DE
		ZIP:			19710

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ACORN FACTOR, INC.
		DATE OF NAME CHANGE:	20060920

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	DATA SYSTEMS & SOFTWARE INC
		DATE OF NAME CHANGE:	19931019

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	DEFENSE SOFTWARE & SYSTEMS INC
		DATE OF NAME CHANGE:	19930328
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-09-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000880984</issuerCik>
        <issuerName>ACORN ENERGY, INC.</issuerName>
        <issuerTradingSymbol>ACFN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001182944</rptOwnerCik>
            <rptOwnerName>MOORE JOHN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACORN ENERGY, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>4 WEST ROCKLAND ROAD</rptOwnerStreet2>
            <rptOwnerCity>MONTCHANIN</rptOwnerCity>
            <rptOwnerState>DE</rptOwnerState>
            <rptOwnerZipCode>19710</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-09-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.6361</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>535911</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>John A. Moore</signatureName>
        <signatureDate>2009-09-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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