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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-03-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001418076</issuerCik>
        <issuerName>Solar Capital Ltd.</issuerName>
        <issuerTradingSymbol>SLRC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001240586</rptOwnerCik>
            <rptOwnerName>SPOHLER BRUCE J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SOLAR CAPITAL LTD., 500 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></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>2020-03-23</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>53526</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.32</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>67526</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2208261</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </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 March 23, 2020 is based on prices ranging from a low of $8.98 per share to a high of $9.95 per share.  The reporting person undertakes to provide to Solar 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 208,248 shares of Solar Capital Ltd. (the &quot;Issuer&quot;) 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.</footnote>
        <footnote id="F3">(Continued from Footnote (2)) In addition, the total includes 1,285,013 shares of the Issuer held by Solar Capital Investors, LLC (&quot;Solar Capital I&quot;) and 715,000 shares of the Issuer held by Solar Capital Investors II, LLC (&quot;Solar Capital II&quot;), a portion of both of which may be deemed to be indirectly beneficially owned by Mr. Spohler, Mr. Gross and a grantor retained annuity trust setup by and for Mr. Gross by virtue of their collective ownership interest therein.</footnote>
        <footnote id="F4">(Continued from Footnote (3)) Mr. Spohler disclaims beneficial ownership of any of the Issuer's securities directly held by the SCP Plan, Solar Capital I or Solar Capital II, 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>Co-Chief Executive Officer and Director</remarks>

    <ownerSignature>
        <signatureName>/s/ Bruce J. Spohler</signatureName>
        <signatureDate>2020-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
