UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549





Form 20-F/A

Amendment No. 1





(Mark One)

| ̈ | REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------------------

OR



|x | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------

For the fiscal year ended December 31, 2010.

OR



| ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

OR



| ̈ | SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | -------------------------------------------------------------------------------------------

Date of event requiring this shell company report

For the transition period from  to

Commission file number: 001-33107





CANADIAN SOLAR INC.

(Exact name of Registrant as specified in its charter)





N/A

(Translation of Registrants name into English)

Canada

(Jurisdiction of incorporation or organization)





650 Riverbend Drive, Suite B

Kitchener, Ontario, Canada N2K 3S2

(Address of principal executive
offices)

Michael G. Potter, Chief Financial Officer

650 Riverbend Drive, Suite B

Kitchener, Ontario, Canada N2K 3S2

Tel: (1-905) 530-2334

Fax: (1-905) 530-2001

(Name, Telephone, E-mail and/or Facsimile number and Address of Company Contact Person)





Securities
registered or to be registered pursuant to Section 12(b) of the Act:



|                                |  |                                                       
|------------------------------- |  | ------------------------------------------------------
|Title of Each Class             |  | Name of Each Exchange on Which Registered             
|Common shares with no par value |  | The NASDAQ Stock Market LLC (The NASDAQ Global Market)

Securities registered or to be registered pursuant to Section 12(g) of the Act:

None

(Title of Class)

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act:

None

(Title of Class)





Indicate the number of outstanding shares of each of the issuers classes of capital or common stock as of the close of the period
covered by the annual report.

42,893,044 common shares issued and outstanding which were not subject to restrictions on
voting, dividend rights and transferability, as of December 31, 2010.

Indicate by check mark if the registrant is a
well-known seasoned issuer, as defined in Rule 405 of the Securities Act.     Yes   ̈
    No  x

If this report is an annual or
transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of
1934.    Yes   ̈    No  x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the
Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90
days.    Yes  x    No   ̈

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every
Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such
files).    Yes   ̈    No   ̈

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See
definition of accelerated filer and large accelerated filer in Rule 12b-2 of the Exchange Act. (Check one):



|                             |  |                        |  |                           
|---------------------------- |  | ---------------------- |  | --------------------------
|Large accelerated filer     ̈ |  | Accelerated filer    x |  | Non-accelerated filer     ̈

Indicate by check mark which basis of accounting the registrant has used to prepare the financial
statements included in this filing: U.S. GAAP  x International Financial Reporting Standards as issued by the International Accounting Standards Board   ̈ Other   ̈

If
Other has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow. Item 17  ̈ Item 18  ̈

If this is an annual report, indicate by check mark whether the registrant is a
shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes   ̈    No  x

(APPLICABLE ONLY TO ISSUERS INVOLVED IN BANKRUPTCY PROCEEDINGS DURING THE PAST FIVE YEARS)

Indicate by check mark whether the registrant has filed all documents and reports required to be filed by Sections 12, 13 or 15(d) of the
Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court.   Yes   ̈    No   ̈









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EXPLANATORY NOTE

This Amendment No. 1 to our annual report on Form 20-F for the year ended December 31, 2010, originally filed with the Securities and Exchange Commission (the SEC) on May 17,
2011 (the Original Report), is being filed solely for purpose of amending Exhibit 4.9, in response to comments received from the Staff of the SEC following a review of our confidential treatment request. Exhibit 4.9 to this Amendment
No. 1 supersedes and replaces the corresponding exhibit to the Original Report.

This Amendment No. 1 consists of a cover page, this
explanatory note, a list of exhibits (Item 19 of Part III), a signature page, Exhibit 4.9 and currently-dated certifications by our principal executive officer and our principal financial officer.

This Amendment No. 1 to Form 20-F speaks as of the initial filing date of the Form 20-F, except for the certifications referenced above. Other than
as expressly set forth above, no part of the Original Report is being amended. Accordingly, other than as discussed above, this Amendment No. 1 does not, and does not purport to, amend, update or restate any other information or disclosure
included in the Original Report or reflect any events that have occurred after the initial filing date of the Original Report. As a result, our annual report on Form 20-F for the fiscal year ended December 31, 2010 continues to speak as of
May 17, 2011.



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|ITEM 19. | EXHIBITS
|-------- | --------



|               |  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|-------------- |  | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Exhibit Number |  | Description of Document                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|               | 
|1.1            |  | Amended Articles of Continuance (incorporated by reference to Exhibit 3.2 of our registration statement on Form F-1 (File No. 333-138144), as amended, initially filed with the
SEC on October 23, 2006)                                                                                                                                                                                                                                                                                                                                                                                
|               | 
|2.2            |  | Indenture, dated as of December 10, 2007, between Canadian Solar Inc. and The Bank of New York, as trustee, including the form of 6.0% Convertible Senior Notes due 2017
(incorporated by reference to Exhibit 4.2 of our registration statement on Form F-3 (File No. 333-149497), as amended, initially filed with the SEC on March 3, 2008)                                                                                                                                                                                                                                          
|               | 
|4.1            |  | Form of Director Indemnity Agreement (incorporated by reference to Exhibit 4.1 of our annual report on Form 20-F for the year ended December 31, 2008 (File No. 001-33107), as
amended, initially filed with the SEC on June 8, 2009)                                                                                                                                                                                                                                                                                                                                                   
|               | 
|4.2           |  | English translation of Supplementary Agreement between Jiangsu Zhongneng Polysilicon Technology Development Co., Ltd., CSI Cells Co., Ltd., Changshu CSI Advanced Solar Inc. and
CSI Central Solar Power Co., Ltd., dated May 22, 2009, supplementing the original Polysilicon Supply Contract dated August 20, 2008 and the original Solar Wafer Supply Contract dated August 20, 2008 (incorporated by reference to Exhibit 4.3 of our
annual report on Form 20-F for the year ended December 31, 2008 (File No. 001-33107), as amended, initially filed with the SEC on June 8, 2009)
|               | 
|4.3           |  | English translation of Long-term (10-Year) Multi-crystalline Wafer Supply Contract between CSI Cells Co., Ltd. and Jiangxi LDK Solar Hi-Tech Co., Ltd., dated June 27, 2008
(incorporated by reference to Exhibit 4.8 of Amendment No. 1 on Form 20-F/A to our annual report on Form 20-F for the year ended December 31, 2008 (File No. 001-33107), filed with the SEC on October 14, 2009)                                                                                                                                                                                            
|               | 
|4.4           |  | English translation of Long-term (10-Year) Multi-crystalline Wafer Supply Contract between CSI Solar Power Inc. and Jiangxi LDK Solar Hi-Tech Co., Ltd., dated June 27, 2008
(incorporated by reference to Exhibit 4.9 of Amendment No. 1 on Form 20-F/A to our annual report on Form 20-F for the year ended December 31, 2008 (File No. 001-33107), filed with the SEC on October 14, 2009)                                                                                                                                                                                           
|               | 
|4.5*           |  | Amended and Restated Share Incentive Plan of the Registrant, dated September 20, 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|               | 
|4.6            |  | Employment Agreement between Canadian Solar Inc. and the Dr. Shawn Qu (incorporated by reference to Exhibit 10.2 of our registration statement on Form F-1 (File No. 333-138144),
as amended, initially filed with the SEC on October 23, 2006)                                                                                                                                                                                                                                                                                                                                         
|               | 
|4.7*           |  | Form of Employment Agreement between Canadian Solar Inc. and its executive officers                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|               | 
|4.8*           |  | English translation of 3rd Supplementary Agreement to the Multi-crystalline Solar Wafer Supply Contract, dated November 24, 2010, among CSI Cells Co., Ltd., Jiangsu Zhongneng
Polysilicon Technology Development Co., Ltd., GCL (Nanjing) Solar Energy Technology Company Limited, Jiangsu GCL Silicon Material Technology Development Co., Ltd., Changzhou GCL Photovoltaic Technology Co., Ltd. and Suzhou GCL Photovoltaic
Technology Co., Ltd.                                                                                                                                     
|               | 
|4.9**         |  | English translation of 4th Supplementary Agreement to the Multi-crystalline Solar Wafer Supply Contract, dated December 31, 2010, between CSI Cells Co., Ltd. and Suzhou GCL
Photovoltaic Technology Co., Ltd.                                                                                                                                                                                                                                                                                                                                                                          
|               | 
|8.1*           |  | List of Subsidiaries                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|               | 
|12.1**         |  | CEO Certification Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|               | 
|12.2**         |  | CFO Certification Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|               | 
|23.1*          |  | Consent of Deloitte Touché Tohmatsu CPA Ltd.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            



|* | Previously filed with the Original Report
|- | -----------------------------------------



|** | Filed herewith
|-- | --------------



| | Confidential treatment has been requested with respect to portions of these exhibits and such confidential treatment portions have been deleted and replaced with
**** and filed separately with the Securities and Exchange Commission pursuant to Rule 24b-2 under the Exchange Act
|- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



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SIGNATURES

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the undersigned to sign this Amendment No. 1 on Form 20-F/A to
this annual report on its behalf.



CANADIAN SOLAR INC.By:

/s/ Shawn (Xiaohua) QuName:

Shawn (Xiaohua) QuTitle:

Chairman, President and
Chief Executive Officer


Date: October 26, 2011