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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-12-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001508171</issuerCik>
        <issuerName>Solar Senior Capital Ltd.</issuerName>
        <issuerTradingSymbol>SUNS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001240586</rptOwnerCik>
            <rptOwnerName>SPOHLER BRUCE J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SOLAR SENIOR CAPITAL LTD.</rptOwnerStreet1>
            <rptOwnerStreet2>500 PARK AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>See Remarks</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-12-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>14.82</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>490609</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price.  These shares were purchased in multiple transactions.  The reported price for the share purchases made on December 11, 2015 is based on prices ranging from a low of $14.75 per share to a high of $14.90 per share.  The reporting person undertakes to provide to Solar Senior Capital Ltd. (the &quot;Issuer&quot;), any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price set forth above.</footnote>
        <footnote id="F2">Includes 35,009 shares of the Issuer held by Solar Capital Partners Employee Stock Plan, LLC (the &quot;SCP Plan&quot;).  The SCP Plan is controlled by Solar Capital Partners, LLC (&quot;Solar Capital Partners&quot;).  Bruce J. Spohler and Michael S. Gross may be deemed to indirectly beneficially own a portion of the shares held by the SCP Plan by virtue of their collective ownership interest in Solar Capital Partners.  In addition, the total includes 455,500 shares of the Issuer held by Solar Senior Capital Investors, LLC (&quot;Solar Senior Investors&quot;) and 100 shares of the Issuer held by Solar Capital Management, LLC (&quot;Solar Management&quot;), a portion of both of which may be deemed to be indirectly beneficially owned by Mr. Spohler and Mr. Gross by virtue of their collective ownership interest therein.</footnote>
        <footnote id="F3">(Continued from Footnote (2)) Mr. Spohler disclaims beneficial ownership of any of the Issuer's securities directly held by the SCP Plan, Solar Senior Investors or Solar Management except to the extent of his pecuniary interest therein, and this report shall not be deemed an admission that Mr. Spohler is the beneficial owner of such securities for purposes of Section 16 or any other purpose.</footnote>
    </footnotes>

    <remarks>Chief Operating Officer and Director</remarks>

    <ownerSignature>
        <signatureName>/s/ Bruce J. Spohler</signatureName>
        <signatureDate>2015-12-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
