<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2022-06-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001868941</issuerCik>
        <issuerName>Fluence Energy, Inc.</issuerName>
        <issuerTradingSymbol>FLNC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000940418</rptOwnerCik>
            <rptOwnerName>SIEMENS AG</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WERNER-VON-SIEMENS-STRASSE 1</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>80333 MUNICH</rptOwnerCity>
            <rptOwnerState>2M</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>GERMANY</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001890016</rptOwnerCik>
            <rptOwnerName>Siemens Industry, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SIEMENS AGSIEMENS INDUSTRY, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>WERNER-VON-SIEMENS-STRASSE 1</rptOwnerStreet2>
            <rptOwnerCity>80333 MUNICH</rptOwnerCity>
            <rptOwnerState>2M</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>GERMANY</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-06-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>58586695</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>58586695</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2022-06-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>58586695</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>58586695</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>LLC Units of Fluence Energy, LLC</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2022-06-30</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>58586695</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>58586695</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On June 30, 2022, Siemens Industry, Inc. (&quot;Siemens Industry&quot;), a wholly owned, indirect subsidiary of Siemens AG, effected an internal transfer to Siemens AG of all of its interest in an aggregate of 58,586,695 shares of Class A Common Stock and exercised its redemption right with respect to an equivalent number of common units of Fluence Energy, LLC (&quot;OpCo Units&quot;) together with the corresponding cancellation of 58,586,695 shares of Class B-1 Common Stock of Fluence Energy, Inc. Siemens Industry exercised such redemption right and transfer as a result of Siemens Industry's and Siemens AG's determination that it would be more suitable for Siemens AG to hold Class A Common Stock rather than Class B-1 Common Stock and OpCo Units.  Siemens AG does not currently contemplate taking any other action at this time with respect to the Class A Common Stock or any other arrangements or agreements with Fluence Energy, LLC or Fluence Energy, Inc., other than in the ordinary course of business.</footnote>
        <footnote id="F2">The OpCo Units and an equal number of shares of Class B-1 Common Stock of Fluence Energy, Inc., together are exchangeable at the discretion of the holder for, at the Issuer's election, shares of Class A Common Stock on a one-for-one basis or the cash value thereof, subject to certain exceptions, conditions and adjustments, and have no expiration date.</footnote>
        <footnote id="F3">The securities are held of record by Siemens Industry. Siemens AG is the indirect parent of Siemens Industry and may be deemed to beneficially own the securities held of record by Siemens Industry.</footnote>
        <footnote id="F4">Following the transfer described above, these securities are held directly by Siemens AG and Siemens Industry no longer holds any securities of the Issuer.  This Form 4 filing reflects an exit filing by Siemens Industry.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>SIEMENS AG, By: /s/ Christian Bleiweiss, Name: Christian Bleiweiss, Title: Chief Counsel Corporate, M&amp;A, By: /s/ Hardi Zajewski, Name: Hardi Zajewski, Title: SVP M&amp;A</signatureName>
        <signatureDate>2022-07-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>SIEMENS INDUSTRY, INC., By: /s/ Ruth Gratzke, Name: Ruth Gratzke, Title: Chief Executive Officer, By: /s/ Marsha Smith, Name: Marsha Smith, Title: Chief Financial Officer</signatureName>
        <signatureDate>2022-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
