SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 13G/A

Amendment No. 1

(Rule 13d-102)

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Solar Capital Ltd.

(Name of Issuer)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

83413U100

(CUSIP Number)

Not Applicable

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)

¨ Rule 13d-1(c)

x Rule 13d-1(d)

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Introductory Note for Schedule 13G

This Amendment No. 1 to the Schedule 13G (this “Amendment No. 1”) is being filed to update the information set forth in the initial Schedule 13G filed with the Securities and Exchange Commission on February 17, 2015 (the “Schedule 13G”). This Amendment No. 1 is filed on behalf of Mr. Michael S. Gross; Mr. Bruce J. Spohler; Solar Capital Investors, LLC, a Delaware limited liability company (“Solar I”); Solar Capital Investors II, LLC, a Delaware limited liability company (“Solar II”); and the 2013 Grantor Retained Annuity Trust setup by and for Mr. Gross and for which he acts as sole trustee (the “GRAT”) to report their beneficial ownership of common stock, par value $0.01 per share (the “Common Stock”) of Solar Capital, Ltd., a Maryland corporation (the “Issuer”).

This Schedule 13G relates to Common Stock of the Issuer purchased by Mr. Gross directly in his personal accounts and by Mr. Gross indirectly through Solar I, Solar II, the GRAT, a profit sharing plan in which Mr. Gross is the sole participant (the “Profit Sharing Plan”) and Solar Capital Partners Employee Stock Plan, LLC (the “SCP Plan”), which is controlled by Solar Capital Partners, LLC (“Solar Partners”). This Schedule 13G also relates to the Common Stock of the Issuer purchased by Mr. Spohler indirectly through Solar I, Solar II and the SCP Plan. Mr. Gross and Mr. Spohler are controlling members of Solar I, Solar II and Solar Partners. Solar Partners is the controlling member of the SCP Plan, and thus, Mr. Gross and Mr. Spohler direct the control of the SCP Plan through Solar Partners. Mr. Gross serves as the sole trustee of the GRAT and, as a result, has sole power to direct the vote and disposition of those shares of Common Stock held by the GRAT. Mr. Gross is the sole participant in the Profit Sharing Plan, and thus, has sole power to direct the vote and disposition of those shares of Common Stock held by the Profit Sharing Plan. Mr. Gross, as beneficial owner of the shares held directly in his personal accounts and indirectly by Solar I, Solar II, the GRAT, the Profit Sharing Plan and the SCP Plan may direct the vote and disposition of 2,293,933 shares of Common Stock. Mr. Spohler, as the beneficial owner of shares held indirectly by Solar I, Solar II and the SCP Plan, may direct the vote and disposition of 2,131,238 shares of Common Stock. Of the above shares, Solar I holds 1,285,013 shares of Common Stock and may direct the vote and disposition of those shares. Solar II holds 715,000 shares of Common Stock and may direct the vote and disposition of those shares. The GRAT holds 20,000 shares of Common Stock and may direct the vote and disposition of those shares. The SCP Plan holds 131,225 shares of Common Stock and may direct the vote and disposition of those shares, and Solar Partners, as the sole member of the SCP Plan, also indirectly controls the shares held by the SCP Plan.

Solar Capital Ltd.

500 Park Avenue

New York, NY 10022

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Mr. Michael S. Gross, Mr. Bruce J. Spohler, Solar Capital Investors, LLC (“Solar I”), Solar Capital Investors II, LLC (“Solar II”) and the 2013 Grantor Retained Annuity Trust (“GRAT”).

500 Park Avenue

New York, NY 10022

Mr. Gross and Mr. Spohler are each United States citizens. Solar I and Solar II are each a limited liability company organized under the laws of the State of Delaware. The GRAT is a trust organized under the laws of the State of New York.

Common Stock, par value $0.01 per share (the “Common Stock”).

83413U100.

Not Applicable.

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(ii) As a controlling member of Solar I, Solar II and Solar Partners (and thus controlling the SCP Plan), Mr. Spohler has shared voting and dispositive power with respect to 2,131,238 shares of Common Stock, which are held by Solar I, Solar II and the SCP Plan.

(iii) As holder of the shares, Solar I has sole voting and dispositive power with respect to 1,285,013 shares of Common Stock.

(iv) As holder of the shares, Solar II has sole voting and dispositive power with respect to 715,000 shares of Common Stock.

(v) As holder of the shares, the GRAT has sole voting and dispositive power with respect to 20,000 shares of Common Stock.

Not Applicable.

Not Applicable.

Not Applicable.

Not Applicable.

Not Applicable.

Not Applicable.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: November 16, 2015

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AMENDED AND RESTATED JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them of a Statement on Schedule 13G dated February 13, 2015 and amended on November 16, 2015 (including amendments thereto) with respect to the Common Stock, par value $0.01 per share, of Solar Capital Ltd. This Amended and Restated Joint Filing Agreement shall be filed as an Exhibit to such Statement. The undersigned acknowledge that each shall be responsible for the timely filing of any amendments to such joint filing and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others.

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