Document:

<PAGE>

                                                                     EXHIBIT 4.9

                                                                  EXECUTION COPY

                                DATED 1 JULY 2006

                        (1)  MR. QU XIAO HUA

                        (2)  HSBC HAV2 (III) LIMITED

                                      and

                        (3)  JAFCO ASIA TECHNOLOGY FUND II

                                   ----------

                              PUT OPTION AGREEMENT

                                  IN RESPECT OF

                               CANADIAN SOLAR INC.

                                   ----------

                                BAKER & MCKENZIE

<PAGE>

THIS AGREEMENT is made on the 1st day of July 2006

BETWEEN:

(1)  MR. QU XIAO HUA, holder of Canadian Passport Number BC289772 and whose
     residential address being at 4056 Jefton Crescent, Mississauga, Ontario,
     Canada L5L 1Z3 (the "FOUNDER");

(2)  HSBC HAV 2 (III) LIMITED, a company incorporated in the Cayman Islands with
     its registered office at 2nd Floor, Strathvale House, North Church Street,
     George Town, Grand Cayman, Cayman Islands (the "FUNDS"); and

(3)  JAFCO ASIA TECHNOLOGY FUND II, a Cayman Islands exempted company with its
     registered office at PO Box 309GT, Ugland House, South Church Street,
     George Town, Grand Cayman, Cayman Islands ("JAFCO").

The Funds and JAFCO shall be referred to collectively as the "INVESTORS" and
individually as an "INVESTOR".

WHEREAS:

(A)  Canadian Solar Inc. (the "COMPANY") is a corporation continued under the
     laws of Canada. Particulars of the Company are set out in Schedule 1.

(B)  The Company, the Founder, the Investors and other parties entered into (i)
     a subscription agreement on 16 November 2005 in relation to the issue of
     Convertible Notes to the Investors and (ii) four supplemental agreements
     relating thereto dated 28 February 2006, 29 March 2006, 9 June 2006 and the
     date of today respectively (collectively, the "SUBSCRIPTION AGREEMENTS").
     The same parties also entered into an investment agreement relating to the
     Company on 30 November 2005 (the "INVESTMENT AGREEMENT").

(C)  Pursuant to the Subscription Agreements, the Company issued to the Funds
     Convertible Notes of an aggregate principal amount of US$7,750,000 and to
     JAFCO Convertible Notes of an aggregate principal amount of US$4,000,000.
     All the Convertible Notes are outstanding as at the date hereof.

(D)  Each of the parties hereto acknowledges that each Investor was requested by
     the Company and the Founder to convert all its outstanding Convertible
     Notes into Common Shares, or any other Shares issued or issuable in respect
     thereof upon any stock split, subdivision, reorganisation or the like, or
     issued or issuable as stock dividend in respect of such Common Shares (the
     "CONVERSION SHARES") as an Optional Conversion (the "CONVERSION"). As a
     condition to the Conversion and in consideration of each Investor agreeing
     to conduct the Conversion, the Founder shall grant an option to each
     Investor to require the Founder to purchase all of the Conversion Shares
     from the relevant Investor or its Affiliate on the terms and conditions set
     out in this Agreement.

                                       1

<PAGE>

(E)  It is contemplated by the parties and the Company that the Common Shares
     (including the Conversion Shares) will undergo a share split immediately
     following the Conversion, and accordingly the price for the option set out
     herein will be adjusted.

NOW, THEREFORE, in consideration of the foregoing recitals, the mutual promises
hereinafter set forth, and other good and valuable consideration, the receipt
and sufficiency of which are hereby acknowledged, THE PARTIES HEREBY AGREE AS
FOLLOWS:

1.   INTERPRETATION

1.1  In this Agreement, capitalized terms shall have the meanings as set out in
     the Subscription Agreements, unless otherwise defined.

1.2  In this Agreement:

     (A)  the headings are inserted for convenience only and shall not affect
          the construction and interpretation of this Agreement;

     (B)  unless the context requires otherwise, words incorporating the
          singular shall include the plural and vice versa and words importing a
          gender shall include every gender;

     (C)  references herein to Clauses, Recitals and Schedules are to clauses
          and recitals of and schedules to this Agreement; and

     (D)  all Recitals and Schedules form part of this Agreement and shall have
          the same force and effect as if expressly set out in the body of this
          Agreement and any reference to this Agreement shall include such
          Recitals and Schedules.

2.   PUT OPTION

2.1  In consideration of each Investor agreeing to conduct the Conversion, the
     Founder hereby grants to each of the Investors severally an option (the
     "PUT OPTION") to require the Founder to purchase all of the Conversion
     Shares held by each Investor or its Affiliate (the "TRANSFER") at the
     option price ("OPTION PRICE") calculated in accordance with the following
     provisions:

     Option Price = US$5.770563156 per Conversion Share,

     on the basis that (i) a total of 5,668,421 Common Shares are currently in
     issue before the Conversion; (ii) the maximum number of Common Shares that
     may be issued pursuant to the ESOP shall be 1,000,000; (iii) an aggregate
     of 2,036,195.824 Common Shares are expected to be issued to all Investors
     upon the full conversion of all Convertible Notes of an aggregate principal
     amount of US$11,750,000.

2.2  In the event the Common Shares shall be increased by share split,
     subdivision, or other similar transaction into a greater number of Common
     Shares, the Option Price then in effect shall, concurrently with the
     effectiveness of such event, be decreased

                                       2

<PAGE>

     in proportion to the percentage increase in the outstanding number of
     Common Shares. In the event the outstanding Common Shares shall be
     decreased by a reverse share split, combination, consolidation, or other
     similar transaction into a smaller number of Common Shares, the Option
     Price then in effect shall, concurrently with the effectiveness of such
     event, be increased in proportion to the percentage decrease in the
     outstanding number of Common Shares.

     For the avoidance of doubt, where the Common Shares shall undergo a share
     split immediately following the Conversion on a 1 for 1.168130772 basis and
     where the maximum number of Common Shares that may be issued pursuant to
     the ESOP shall remain 1,000,000 notwithstanding the share split:

     Option Price = US$4.94 per Conversion Share,

     on the basis that the aggregate shareholding of all Investors in the
     Company following the share split shall be 23.79%.

2.3  Subject to Clause 2.4 below, the Put Option may be exercisable from time to
     time in whole or in part.

2.4  The Put Option is exercisable by each of the Investors, by serving a
     written option notice (the "OPTION NOTICE") on the Founder in accordance
     with Clause 7 and

     (A)  at any time from 31 March 2007 (inclusive) to 10 April 2007
          (inclusive) in the event that the Company has not completed a
          Qualified IPO on or before 31 March 2007; or

     (B)  at any time after the occurrence and during the continuance of an
          Event of Default upon written demand from any of the Investors, which
          demand may be served by the Investors at any time following the date
          on which such Event of Default becomes known to such Investor.

2.4  The Option Notice shall, concurrently with delivery to the Founder, be
     delivered to the other Investor(s). Upon receipt of the Option Notice, the
     other Investor(s) may also elect to exercise the Put Option by delivering a
     separate option notice ("SECOND OPTION NOTICE") to the Founder (copying all
     other Investors) within ten (10) days of the receipt of the Option Notice.

2.5  For the purpose of Clause 2.4(B) above, the Founder hereby undertakes with
     each of the Investors that upon him becoming aware of the occurrence of any
     Event of Default, he will promptly give written notice thereof to each of
     the Investors.

2.6  Any Option Notice served by any Investor pursuant to Clause 2 shall contain
     a statement to the effect that such Investor wishes to exercise the Put
     Option and shall set out in as much details as reasonably possible
     particulars of the event which forms the basis for the exercise of the Put
     Option, the number of Conversion Shares to be transferred by such Investor
     or its Affiliate pursuant to the said notice, the Option Price and the
     place where the Transfer of the Conversion Shares shall take place.

                                       3

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2.7  The completion of the Transfer of the Conversion Shares upon exercise of
     the Put Option by an Investor pursuant to Clauses 2.4 and/or 2.5 shall take
     place as soon as possible after the Investor or its Affiliate has provided
     the Founder with a certificate under section 116 of the Income Tax Act
     (Canada) as referred to in Clause 2.9, whereupon the Founder shall deliver
     to such Investor or its Affiliate payment of the Option Price in respect of
     the total number of the Conversion Shares stated in the Option Notice, or
     in the Second Option Notice, as the case may be. Upon receipt of the
     payment aforesaid, such Investor or its Affiliate shall deliver to the
     Founder or its nominee the relevant shares certificate(s) in respect of the
     said Conversion Shares and duly executed instrument of transfer. At such
     completion, the Investor or its Affiliate shall represent and warrant that
     the Conversion Shares subject to the Put Option are free and clear of all
     Encumbrances and Liens (other than those imposed by this Agreement, the
     Investment Agreement, the Registration Rights Agreement and the Articles of
     Incorporation and By-Laws) and that the Investor or its Affiliate has full
     authority to transfer such shares to the Founder or his nominee.

2.8  Provided that each Investor or its Affiliate provides the Founder with a
     certificate under section 116 of the Income Tax Act (Canada) with the
     appropriate certificate limit, the Option Price payable to any Investor or
     its Affiliate shall be paid to such Investor or its relevant Affiliate, by
     way of banker's draft or cashier's order, in United States dollars in full
     without any deduction or withholding for or on account of any present or
     future taxes, levies, imposes, duties or other charges, fees, withholdings,
     restrictions or conditions, and without set-off, counterclaim or any
     deduction whatsoever.

2.9  Where applicable, the Founder shall procure the approval of the Company's
     board of directors on each Transfer of the Conversion Shares.

2.10 Subject to the provisions of Clause 2.4, the parties hereto agree that
     there shall be no limit to the timing and numbers of Option Notices.

2.11 The right of each Investor to exercise the Put Option shall be independent
     of the decision of the other Investor. For avoidance of doubt, one Investor
     may require the Founder to complete a Transfer even if the other Investor
     does not so require.

2.12 The Founder agrees to bear all taxes and stamp duty, if any, payable on
     each Transfer.

2.13 The parties hereto acknowledge that any Transfer (a) shall be free from the
     transfer restrictions imposed on the Investors in the Investment Agreement
     but (b) shall not otherwise affect or prejudice the rights of any Investor
     under the Investment Agreement, the Subscription Agreements, the
     corresponding certificates of the Convertible Notes, the Registration
     Rights Agreement and the Articles of Incorporation and By-Laws.

3.   VARIATION

     No variation of this Agreement (or any document entered into pursuant to
     this Agreement) shall be valid unless it is in writing and signed by or on
     behalf of each of the parties hereto.

                                       4

<PAGE>

4.   SUCCESSORS AND ASSIGNS

     All rights, covenants and agreements of the parties hereto contained in
     this Agreement shall, except as otherwise provided herein, be binding upon
     and inure for the benefit of their respective successors or permitted
     assigns, provided that the Founder shall not assign any of his rights under
     this Agreement without the prior written consent of all of the Investors.
     Notwithstanding anything to the contrary in this Agreement, each of the
     Investor is entitled to assign its rights in and benefit of this Agreement
     to any third parties to which such Investor shall have transferred the
     beneficial ownership of the Conversion Shares (or any interest therein held
     by such Investor).

5.   FURTHER ASSURANCE

     Each party hereto shall do or procure to be done all such further acts and
     things, and execute or procure the execution of all such other documents,
     as the other parties may from time to time reasonably require for the
     purpose of giving to the other parties the full benefit of all of the
     provisions of this Agreement.

6.   WAIVER; SEVERANCE

6.1  The failure of any party hereto at any time to require performance or
     observance by any other party of any provision of this Agreement shall in
     no way affect the right of such first party to require performance of that
     provisions; and any waiver by any party of any breach of any provision of
     this Agreement shall not be construed as a waiver of any continuing or
     succeeding breach of such provision, a waiver of the provision itself or a
     waiver of any right under this Agreement.

6.2  Should any provision of this Agreement be declared null and void by any
     competent government agency or court this shall not effect the other
     provisions of this Agreement which are capable of severance and which shall
     continue unaffected.

7.   NOTICES

7.1  Notices or other communications required to be given by any party hereto
     pursuant to this Agreement shall be written in English and may be delivered
     personally or sent by registered airmail or postage prepaid, by a
     recognized courier service or by facsimile transmission to the address of
     the other relevant parties set forth below. The dates on which such notices
     shall be deemed to have been effectively given shall be determined as
     follows:

     (A)  notices given by personal delivery shall be deemed effectively given
          on the date of personal delivery;

     (B)  notices given by registered airmail or postage prepaid shall be deemed
          effectively given on the fifth (5th) Business Day after the date on
          which they were mailed (as indicated by the postmark);

     (C)  notices given by courier shall be deemed effectively given on the
          second (2nd) Business Day after they were sent by recognized courier
          service; and

                                       5

<PAGE>

     (D)  notices given by facsimile transmission shall be deemed effectively
          given immediately following confirmation of its transmission as
          recorded by the sender's facsimile machine.

          TO THE FOUNDER:

          Address:                                [chinese characters]
                                                  (Building A6, Export
                                                  Processing Zone
                                                  Suzhou New & Hi-Tech District
                                                  Jiangsu Province 215151
                                                  The People's Republic of
                                                  China)
          Fax Number:                             86-512-62696016

          TO THE FUNDS:

          c/o HSBC Private Equity (Asia) Ltd.
          Address:                                Level 17, 1 Queen's Road
                                                  Central
                                                  Hong Kong
          Fax Number:                             +852 2845-9992
          Attention:                              The Managing Director

          TO JAFCO:

          c/o JAFCO Investment (Asia Pacific) Ltd
          Address:                                6 Battery Road
                                                  #42-01 Singapore 049909
          Fax Number:                             +65 6221-3690
          Attention:                              The President

          With a copy to:
          JAFCO Investment (Hong Kong) Ltd.
          Address:                                30/F Two International Finance
                                                  Centre
                                                  8 Finance Street
                                                  Central
                                                  Hong Kong
          Fax Number:                             +852 2536-1979
          Attention:                              General Manager
          Email:                                  All E-mail correspondence to
                                                  vincent.chan@jafcoasia.com and
                                                  sam.lai@jafcoasia.com

7.2  Any party may at any time change its address or fax number for service of
     notices in writing delivered to the other parties in accordance with this
     Clause 7.

8.   COUNTERPARTS

     This Agreement may be executed in any number of counterparts and by the
     parties hereto on separate counterparts, each of which when so executed
     shall be an original, but all of which shall together constitute one and
     the same instrument.

                                       6

<PAGE>

9.   PROCESS AGENTS

9.1  Each party hereby irrevocably appoints the person set out opposite its name
     below as its respective agent to accept service of process in Hong Kong in
     any legal action or proceedings arising out of this Agreement, service upon
     whom shall be deemed completed whether or not such service of process is
     forwarded to such party by its agent or received by it, and each party
     warrants and undertakes to the other parties that the agent appointed by it
     hereunder is a company incorporated in Hong Kong and the address of such
     agent set out below is its registered office address in Hong Kong:

<TABLE>
<CAPTION>
                                        AGENT /
     PARTY                      REGISTERED OFFICE ADDRESS
----------------   ----------------------------------------------------
<S>                <C>
For the Founder:   Key Consultant Limited

                   Address: Unit 710, 7th Floor, Bank of America Tower,
                   12 Harcourt Road, Central, Hong Kong

The Funds          HSBC Private Equity (Asia) Ltd.

                   Address: Level 17, 1 Queen's Road Central, Hong Kong

JAFCO              JAFCO Investment (Hong Kong) Ltd.

                   Address: 30/F  Two  International  Finance  Centre,
                   8 Finance Street, Central, Hong Kong
</TABLE>

9.2  If a process agent appointed by any party pursuant to Clause 9 ceases to be
     able to act as such or to have a registered office address in Hong Kong,
     the party which appoints such process agent shall appoint a new process
     agent, which shall be a company incorporated in Hong Kong, and to deliver
     to the other parties, before the expiry of fourteen (14) days from the date
     on which such process agent ceases to be able to act as such or to have a
     registered office address in Hong Kong, a copy of the written acceptance of
     appointment by that new process agent.

9.3  Nothing in this Agreement shall affect the right to serve process in any
     other manner permitted by law or the right to bring proceedings in any
     other jurisdiction for the purposes of the enforcement or execution of any
     judgement or other settlement in any other courts.

10.  GOVERNING LAW

     This Agreement is governed by and shall be construed in accordance with the
     laws of Hong Kong.

11.  DISPUTE RESOLUTION

                                       7

<PAGE>

11.1 Any dispute, controversy or claim arising out of or connected with this
     Agreement or the interpretation, breach, termination or validity hereof,
     including a dispute as to the validity or existence of this Agreement,
     shall be resolved by way of arbitration upon the request of any of the
     parties in dispute with notice to the other parties.

11.2 Arbitration under this Clause 11 shall be conducted in Hong Kong, under the
     auspices of the Hong Kong International Arbitration Centre (the "HKIAC") by
     three arbitrators (the "ARBITRATORS") pursuant to the rules of the United
     Nations Commission on International Trade Law (the "UNCITRAL RULES"), save
     that, unless the parties in dispute agree otherwise:

     (A)  the three Arbitrators shall be appointed by the HKIAC; and

     (B)  the parties agree to waive any right of appeal against the arbitration
          award.

11.3 The arbitration shall be administered by HKIAC in accordance with HKIAC's
     procedures for arbitration.

11.4 Each party shall cooperate with the others in making full disclosure of and
     providing complete access to all information and documents requested by
     another party in connection with such arbitration proceedings, subject only
     to any confidentiality obligations binding on the disclosing party.

11.5 The award of the arbitral tribunal shall be final and binding upon the
     disputing parties, and a prevailing party may apply to any court of
     competent jurisdiction for enforcement of such award.

11.6 The cost of the arbitration (including the reasonable and properly incurred
     fees and expenses of the lawyers appointed by each party to the
     arbitration) shall be borne by the party or parties against whom the
     arbitration award is made or otherwise in accordance with the ruling of the
     arbitration tribunal.

11.7 Any party shall be entitled to seek preliminary injunctive relief, if
     possible, from any court of competent jurisdiction pending the constitution
     of the arbitral tribunal.

12.  JAFCO'S RIGHTS

     All parties acknowledge and agree that any rights of JAFCO under this
     Agreement may, without prejudice to the rights of JAFCO to exercise any
     such rights, be exercised by JAFCO Investment (Asia Pacific) Ltd. ("JIAP")
     or any other fund manager of JAFCO or their nominees (each, a "JAFCO
     MANAGER"), unless JAFCO has (a) given notice to the other parties that any
     such rights cannot be exercised by JIAP or a JAFCO Manager; and (b) not
     given notice to the other parties that such notice given under paragraph
     (a) above has been revoked.

IN WITNESS WHEREOF this Agreement has been executed by the parties the day and
year first before written.

                                       8

<PAGE>

                                   SCHEDULE 1

                           PARTICULARS OF THE COMPANY

NAME:                          Canadian Solar Inc.

DATE OF INCORPORATION:         22 October 2001

PLACE OF ORGANISATION:         Canada

REGISTERED OFFICE:             4056 Jefton Crescent. Mississauga, Ontario,
                               Canada L5L 1Z3

ISSUED  CAPITAL (AS OF THE     5,668,421 Common Shares with no nominal or par
DATE HEREOF):                  value

<TABLE>
<CAPTION>
SHAREHOLDERS AS AT THE DATE
HEREOF:                        SHAREHOLDER   NO. OF EQUITY SECURITIES HELD
---------------------------    -----------   -----------------------------
<S>                            <C>           <C>
                               QU Xiao Hua   5,668,421 Common Shares
</TABLE>

<TABLE>
<CAPTION>
CONVERTIBLE NOTES ISSUED AND
OUTSTANDING AS AT THE DATE                  PRINCIPAL AMOUNT OF
HEREOF:                          HOLDER    THE CONVERTIBLE NOTES
----------------------------   ---------   ---------------------
<S>                            <C>         <C>
                               The Funds        US$7,750,000
                               JAFCO            US$4,000,000
</TABLE>

                                       9

<PAGE>

SIGNED, SEALED and DELIVERED   )
as a Deed by                   )   /s/
QU XIAO HUA                    )
in the presence of:-           )

/s/

                                       10

<PAGE>

SIGNED by Victor Leung    )
for and on behalf of      )   /s/
HSBC HAV2 (III) LIMITED   )
in the presence of:-      )

/s/
-------------------------------------
Laetitia K.W. Yu
Witness

                                       11

<PAGE>

SIGNED by Hiroshi Yamada                 )
for and on behalf of                     )   /s/
JAFCO ASIA TECHNOLOGY FUND II            )
in the presence of:- Liu Xiao Ning /s/   )

                                       12
<PAGE>

                               DATED JULY 28, 2006

                       (1)  MR. QU XIAO HUA

                       (2)  HSBC HAV2 (III) LIMITED

                       (3)  JAFCO ASIA TECHNOLOGY FUND II

                                      AND

                       (4)  JAFCO ASIA TECHNOLOGY FUND II

                            (BARBADOS) LIMITED

                                   ----------

                        SUPPLEMENTAL PUT OPTION AGREEMENT

                                  IN RESPECT OF

                               CANADIAN SOLAR INC.

                                   ----------

<PAGE>

THIS SUPPLEMENTAL AGREEMENT is made on the 28th day of July 2006

BETWEEN:

(1)  MR. QU XIAO HUA, holder of Canadian Passport Number BC289772 and whose
     residential address being at 4056 Jefton Crescent, Mississauga, Ontario,
     Canada L5L 1Z3 (the "FOUNDER");

(2)  HSBC HAV 2 (III) LIMITED, a company incorporated in the Cayman Islands with
     its registered office at 2nd Floor, Strathvale House, North Church Street,
     George Town, Grand Cayman, Cayman Islands (the "FUNDS");

(3)  JAFCO ASIA TECHNOLOGY FUND II, a Cayman Islands exempted company with its
     registered office at PO Box 309GT, Ugland House, South Church Street,
     George Town, Grand Cayman, Cayman Islands ("JAFCO CAYMAN"); and

(4)  JAFCO ASIA TECHNOLOGY FUND II (BARBADOS) LIMITED, a Corporation
     incorporated under the laws of Barbados and with its registered office
     situate at 13, 8th Avenue Belleville in the parish of St. Michael in
     Barbados ("JAFCO BARBADOS").

The Funds and JAFCO Barbados shall be referred to collectively as the
"INVESTORS" and individually as an "INVESTOR".

WHEREAS:

(A)  The Founder, the Funds and JAFCO Cayman entered into a put option agreement
     (the "PUT OPTION AGREEMENT") on July 1, 2006, pursuant to which, each of
     the Funds and JAFCO Cayman shall have the right to request the Founder to
     purchase certain number of Conversion Shares from each of them.

(B)  JAFCO Cayman and JAFCO Barbados entered into a share sale and purchase
     agreement on July 17, 2006 (the "SHARE SALE AND PURCHASE AGREEMENT").
     Further to and in connection with the said Share Sale and Purchase
     Agreement, JAFCO Cayman and JAFCO Barbados entered into an assignment
     agreement dated July 17, 2006, pursuant to which, JAFCO Cayman assigns to
     JAFCO Barbados all its rights under the Put Option Agreement.

(C)  The parties hereto are desirous of modifying certain terms in the Put
     Option Agreement on the terms and subject to the conditions set forth
     herein.

     NOW, THEREFORE, in consideration of the foregoing recitals, the mutual
promises hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, THE PARTIES HEREBY
AGREE AS FOLLOWS:

3.   AMENDMENTS TO THE PUT OPTION AGREEMENT

The parties hereto agree that, in order to conform to the original intention of
the parties, Clause 2.4 of the Put Option Agreement shall be deleted in its
entirety and replaced with the following and such replacement shall take effect
on the date of the Put Option Agreement:

                                        1

<PAGE>

"2.4 THE PUT OPTION IS EXERCISABLE BY EACH OF THE INVESTORS, BY SERVING A
WRITTEN OPTION NOTICE (THE "OPTION NOTICE") ON THE FOUNDER IN ACCORDANCE WITH
CLAUSE 7 AND

     (A)  AT ANY TIME FROM 31 MARCH 2007 (INCLUSIVE) TO 10 APRIL 2007
          (INCLUSIVE) IN THE EVENT THAT THE COMPANY HAS NOT COMPLETED AN IPO ON
          OR BEFORE 31 MARCH 2007; OR

     (B)  AT ANY TIME AFTER THE OCCURRENCE AND DURING THE CONTINUANCE OF AN
          EVENT OF DEFAULT UPON WRITTEN DEMAND FROM ANY OF THE INVESTORS, WHICH
          DEMAND MAY BE SERVED BY THE INVESTORS AT ANY TIME FOLLOWING THE DATE
          ON WHICH SUCH EVENT OF DEFAULT BECOMES KNOWN TO SUCH INVESTOR."

2.   MISCELLANEOUS

2.1 Definitions. In this Supplemental Agreement, capitalized terms shall have
the meanings as set out in the Put Option Agreement, unless otherwise defined.

2.2 Assignment. This Supplemental Agreement shall be binding upon and shall
inure to the benefit of the parties hereto and their respective successors and
assigns. No party to this Supplemental Agreement shall assign any of its rights
hereunder without the written consent of the other parties.

2.3 Counterparts. This Supplemental Agreement may be executed in counterparts,
each of which shall be deemed to be an original with the same effect as if the
signatures thereto and hereto were upon the same instrument.

2.4 Survival. All other provisions of the Put Option Agreement which are not
specifically amended pursuant to Clause 1 of this Supplemental Agreement shall
survive this Supplemental Agreement and continue in full force and effect.

2.5 Governing Law. This Supplemental Agreement is governed by and shall be
construed in accordance with the laws of Hong Kong.

                            [SIGNATURE PAGES FOLLOW]

                                        2

<PAGE>

SIGNED, SEALED and DELIVERED               )
as a Deed by                               )
QU XIAO HUA                                )   /s/
in the presence of:-                       )

                                        3

<PAGE>

SIGNED by Victor Leung                     )
for and on behalf of                       )
HSBC HAV2 (III) LIMITED                    )   /s/
in the presence of:-                       )

                                        4

<PAGE>

SIGNED by CHAN CHUN HUNG VINCENT         )
for and on behalf of                     )
JAFCO ASIA TECHNOLOGY FUND II            )   /s/
in the presence of:- Wong Yun Pun /s/    )

SIGNED by HIROSHI YAMADA                 )
for and on behalf of                     )
JAFCO ASIA TECHNOLOGY FUND II            )
(BARBADOS) LIMITED                       )   /s/
in the presence of:- Liu Xiao Ning /s/   )

                                       5<PAGE>
                                                                    EXHIBIT 4.10

                                 July 28, 2006

Canadian Solar Inc.
(CHINESE CHARACTERS)
(Building A6, Export Processing Zone
Suzhou New & Hi-Tech District
Jiangsu Province 215151
The People's Republic of China)
Fax No.:   86-512-62696016
Attention: Mr. QU Xiao Hua

Mr. QU Xiao Hua
(CHINESE CHARACTERS)
(Building A6, Export Processing Zone
Suzhou New & Hi-Tech District
Jiangsu Province 215151
The People's Republic of China)

Dear Sirs:

     When HSBC HAV2 (III) Limited ("HSBC") and JAFCO Asia Technology Fund II
("JAFCO") converted all of their convertible notes of Canadian Solar Inc. (the
"Company") into the Company's common shares (the "Common Shares") on July 1,
2006, they acknowledged and agreed that Mr. Qu's right to the Company's retained
earnings as of February 28, 2006 under Condition (B)2(d) of the terms and
conditions of the convertible notes would remain in effect.

     It is proposed to give effect to Mr. Qu's right by:

          (i) the transfer to Mr. Qu of 30,761 and 15,877 Common Shares from
     HSBC and JAFCO, respectively; and

          (ii) the issue under the Company's Share Incentive Plan of (a) 50,000
     restricted shares, and (b) options to purchase 20,000 Common Shares at an
     exercise price of US$10.00 per Common Share, both with vesting periods of
     four years, to Hanbing Zhang, who is the wife of Mr. Qu.

     Each of HSBC, JAFCO, Mr. Qu and the Company will take all necessary actions
to implement the above proposal, including, without limitation, entering into
share transfer agreements, delivering share certificates, adopting board
resolutions, and in the case of HSBC, JAFCO and Mr. Qu, voting or causing their
respective nominees to vote in favor of resolutions of the Company's board of
directors authorizing such actions.

     Upon completion of the transfer of Common Shares to Mr. Qu and the issue of
restricted shares and share options outlined above, all rights and obligations
of the parties with respect to the Company's retained earnings as of February
28, 2006 will be fully satisfied and discharged.

     If the foregoing correctly sets forth the agreement between HSBC, JAFCO,
Mr. Qu and the Company, please indicate your acceptance in the space provided
below for that purpose.

                                       1

<PAGE>

                                                  Very truly yours,

                                                  HSBC HAV2 (III) LIMITED

                                                  By:    /s/
                                                      -------------------------
                                                      Name: Victor Leung
                                                      Title:

                                                  JAFCO ASIA TECHNOLOGY FUND II

                                                  By:    /s/
                                                      -------------------------
                                                      Name:  Hiroshi Yamada
                                                      Title: Attorney

Accepted and agreed by:

QU XIAOHUA

   /s/
------------------------------------

CANADIAN SOLAR INC.

By:       /s/
    ----------------------------------------
    Name:
    Title:

                                       2

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