Document:

<PAGE>

                                                                   Exhibit 10.18

                             (Summary Translation)

                    SOLAR CELL SILICON WAFER SUPPLY AGREEMENT

Party A: Canadian Solar Inc.                                      CSI-LDK060602W

Address: Mississauga, Ontario, Canada

Party B: Jiangxi LDK Solar High-Tech Co., Ltd.

Address: Xinyu City High Technology Development Zone, Jiangxi Province

Whereas:

1.   Party A and Party B have friendly cooperative relationship;

2.   Party A has decided to invest in and form a solar cell silicon wafer
     production line in China;

After friendly consultation, Party A and Party B hereby reach the following
agreement on Party B's supply of polycrystalline silicon to Party A:

Article 1 Product Supply

Party B agrees to supply polycrystalline silicon wafer products ("Product") to
Party A according to this Agreement in such quantity as determined in accordance
with the relevant provisions of this Agreement.

Party A will carry out the actual procurement through its subsidiary in China
designated by it.

Article 2 Quantity of Supply

<TABLE>
<CAPTION>
                                Quantity
             ---------------------------------------------
      Year   Quarter 1   Quarter 2   Quarter 3   Quarter 4
      ----   ---------   ---------   ---------   ---------
<S>   <C>    <C>         <C>         <C>         <C>
1     2007     1 MW          3 MW      5 MW        6 MW
2     2008                  50 MW
3     2009                  75 MW
4     2010                 108 MW
</TABLE>

<PAGE>

Article 3 Quality Standard and Specifications

Party B shall make deliveries to Party A according to its publicly announced
product quality standard and specifications.

Article 4 Principle for Determination of Supply Price and Payment

1.   The price of the Product to be supplied by Party B to Party A shall be the
     uniform price at which Party B supplies the Product to all major companies
     at that time. In principle, the price shall be determined on a monthly
     basis. Once determined, the price shall remain unchanged for at least one
     month.

2.   Party A agrees that after this Agreement duly comes into effect it will
     make an advance payment at 60% of the price to Party B as deposit six
     months before Party B begins to make deliveries, with the remaining 40% of
     the price to be paid in full within 30 days before Party B makes
     deliveries.

Article 5 Procedure of Supply

1.   Party A and Party B shall agree in writing on the material terms of the
     supply, such as the price of the Product, quantity, quality,
     specifications, delivery schedule and amount of deposit payment, under
     separate covers prior to each delivery period.

2.   Party B shall issue a supply order to Party A 45 days prior to a delivery
     specifying the delivery quantity, quality, specification and delivery
     schedule.

3.   Upon receipt of Party B's order, Party A shall confirm the supply order in
     writing within 5 days. A purchase order finally confirmed by both Parties
     in writing shall be the final basis of the supply of the Product for the
     delivery period concerned. If any Party proposes to change the delivery
     quantity or delivery time after such confirmation, that Party shall notify
     the other Party 10 days in advance and obtain the written consent of the
     other Party, otherwise it shall be liable for breach of contract
     accordingly.

4.   Mode of delivery: Delivery shall be taken by Party A itself according to
     the delivery date and quantity finally confirmed by the Parties and, when
     Party A takes delivery, the Parties shall confirm the quantity of the
     Product and complete the delivery formalities in writing onsite.

Article 7 Acceptance and Objection

Party A shall carry out acceptance on the very day of receipt of the Product and
shall raise any objection it may have with regard to the quality of the Product
within 90 days of receipt of the Product. If it fails to do so within this
period, it shall be deemed to have no objection.

                                       -2-

<PAGE>

Article 8 Liability for Breach of Contract

If any Party violates any provision of this Agreement, it shall be liable for
breach of contract accordingly. If the quality of any Product supplied by Party
B does not conform to that agreed by the Parties, Party A has the right to
return the Product to Party B within 90 days and Party B shall promptly replace
the Product upon receipt of it from Party A.

The Parties agree that in the following circumstances Party A has the right to
demand the return of the advance payment:

     (1)  Party B fails to make deliveries on schedule and according to the
          quality requirement;

     (2)  The Parties fail to reach an agreement on the specific price of the
          goods;

     (3)  Party B suspends production for a long period (over three months),
          becomes bankrupt or encounters other material changes;

     (4)  There is a material change in the equity structure of Party B or Party
          B's major shareholder;

     (5)  Party B fails to perform its obligations as required by this
          Agreement.

Party B shall return the advance payment in full within 30 days after Party A
issues a written demand for the return of the advance payment and the
obligations under this Agreement will not be deemed terminated until
confirmation is given by both Parties.

Article 9 Governing Law and Jurisdiction Over Disputes

1.   The conclusion, validity, interpretation and performance of and the
     resolution of disputes relating to this Agreement shall be governed by the
     laws of the mainland area of the People's Republic of China.

2.   All disputes arising from or in connection with the performance of this
     Agreement shall be resolved by the Parties through amicable consultation;
     if such consultation fails to resolve a dispute, either Party may apply to
     the Suzhou Contract Arbitration Commission for arbitration by an
     arbitration tribunal formed by the arbitration commission in accordance
     with the arbitration rules of that arbitration commission in effect at the
     time of the application. The arbitration award shall be final and binding
     on both Parties.

Article 10 Effectiveness of Agreement

This Agreement shall come into effect after it is signed by the legal
representatives or authorized representatives of the Parties.

                                       -3-

<PAGE>

Article 11 Miscellaneous

This Agreement shall be written in quadruplicate with Party A and Party B each
holding two copies (including one original and one duplicate), and all four
copies of the Agreement shall have equal legal effect.

                                       -4-

<PAGE>

(No text of the main body hereafter)

Party A: Canadian Solar, Inc.

         Legal representative or authorized representative:

         /s/ Xiaohu Wang
         -------------------------------

         July 6, 2006

Party B: Jiangxi LDK Solar Energy High-Tech Limited Liability Company

         Legal representative or authorized representative:

         /s/ Xiaofeng Peng
         -------------------------------

         July 6, 2006

                                       -5-

<PAGE>
                             (Summary Translation)

             SOLAR CELL SILICON WAFER SUPPLY SUPPLEMENTAL AGREEMENT

                                                               NO. 60810 CSI/LDK

Party A: Canadian Solar Inc.

Address: 4056 Jefton Crescent, Mississauga, Ontario, L5L 1Z3 Canada

Party B: Jiangxi LDK Solar Energy High-Tech Limited Liability Company

Address: Xinyu City High Technology Development Zone, Jiangxi Province

Based on their respective developmental needs, Party A and Party B hereby
supplement the Solar Cell Silicon Wafer Supply Agreement of No. CSI-LDK060602W
that they have executed.

Party B agrees to amend the quantity of supply stipulated in the above-said
agreement as follows:

<TABLE>
<CAPTION>
                                  Quantity
             ---------------------------------------------
      Year   Quarter 1   Quarter 2   Quarter 3   Quarter 4
      ----   ---------   ---------   ---------   ---------
<S>   <C>    <C>         <C>         <C>         <C>
1     2007      1 MW         4 MW       8 MW       12 MW
2     2008                  50 MW
3     2009                  75 MW
4     2010                 108 MW
</TABLE>

Other provisions shall remain unchanged.

Party A: /s/ Xiaohua Xu (signature)       Party B: /s/ Xiaofeng Peng (signature)

Representative:                        Representative:
                ---------------------                   ------------------------

Date: August 11, 2006                   Date: August 11, 2006<PAGE>
                                                                   Exhibit 10.19

                             (Summary Translation)

                            SILICON SUPPLY AGREEMENT

                                                Contract Number: SFBE-061111-LDK
                                      Place of Signing: 666 Linyang Road, Qidong
                                              Date of Signing: November 11, 2006

The Seller: Jiangxi LDK Solar Hi-Tech Co., Ltd.
The Buyer: Jiangsu Linyang Solarfun Co., Ltd.

Based on the status of the performance of Contracts 2005-LY1208, 2006-LY0528
and LDK20060727ZLB, and taking into consideration of the needs of both parties
in the course of their development, the Seller and the Buyer hereby enter into
this Agreement on Amendments to Product Supply Contracts (this "Agreement")
after friendly negotiations.

Article 1.     Contract 2005-LY1208 shall be terminated with respect to the
               unperformed obligations thereunder. Such unperformed obligations
               consist of 1.38 million pieces of silicon wafers that shall be
               but have not been supplied to the Buyer by the Seller under such
               contract, and RMB37,521,120 that has been prepaid by the Buyer
               to the Seller under such contract for the purpose of such
               silicon wafers.

Article 2.     Contract 2006-LY0528 shall be terminated with respect to the
               unperformed obligations thereunder. Such unperformed obligations
               consist of 1.98 million pieces of silicon wafers that shall be
               but have not been supplied to the Buyer by the Seller under such
               contract, and RMB57,087,744 that has been prepaid by the Buyer
               to the Seller under such contract for the purpose of such
               silicon wafers.

Article 3.     Contract LDK20060727ZLB shall be terminated with respect to the
               unperformed obligations thereunder. Such unperformed obligations
               consist of 0.25 million pieces of multicrystalline silicon
               wafers (converted from the quantity of the unsupplied products)
               that shall be but have not been supplied to the Buyer by the
               Seller under such contract, and RMB12,648,500 that has been
               prepaid by the Buyer to the Seller under such contract for the
               purpose of such silicon wafers.

Article 4.     The Commissioned Processing Contract 2005-LY1209 shall be
               terminated. Notwithstanding such termination, the Seller shall,
               prior to November 25, 2006 perform all of its obligations to
               complete the processing of those products that has actually been
               commissioned to it by the Buyer.

Article 5.     The Cooperation Agreement dated December 16, 2005 by and between
               the parties hereto shall be terminated and any obligations
               thereunder the performance of which has been commenced shall
               continue to be performed in accordance with the original
               provisions thereof.

<PAGE>

               The above five contracts shall hereinafter be referred to
               collectively as the "Terminated Contracts."

Article 6.     Any shortfall in the quantity of, and any unqualified or
               otherwise defective silicon wafers in, any batch of the silicon
               wafers that has been delivered as a result of the performance of
               any of the Terminated Contracts, shall be made up or replaced
               prior to December 25, 2006, as the case may be.

Article 7.     Any and all deposits and advance payments paid for the purpose
               of those products that are left unsupplied under the Terminated
               Contracts shall be converted into the advance payments under this
               Agreement. The amount of such deposits and advance payments shall
               be determined as RMB98,952,900.80 for the time being. The parties
               hereto agree that the accurate amount of such advance payments so
               converted shall be subject to the final amount mutually confirmed
               by the accounting departments of the parties hereto subsequently.
               If such final amount is higher than RMB98,952,900.80, then the
               excess shall be repaid by the Seller to the Buyer or vice versa.

Article 8.     The parties hereto agree that beginning from December 2006 they
               shall perform this Agreement as follows:

               Agreed quantity, name, technical specifications, price and
               delivery schedule of the subject products;

<TABLE>
<CAPTION>
--------------------------------------------------------------------------------------------------------
  NAME OF SUBJECT        TECHNICAL SPECIFICATIONS                         QUANTITY       PRETAX UNIT
     PRODUCT                                                                                 PRICE
                                                                                             (RMB
                                                                                          YUAN/PIECE)
--------------------------------------------------------------------------------------------------------
<S>                      <C>                                               <C>            <C>
                         1. DIMENSIONS OF SUBJECT SILICON WAFERS:

                         1.1 Contour of subject silicon wafers:
                         125x125+/-0.5mm

                         1.2 Thickness of subject silicon wafers:
                         240+/-20(u)m

                         1.3 Total thickness variation(TTV): 0.03mm

                         1.4 Vertical angle: diagonal lines in the
                         internal square having equal length, within a
                         tolerance of +/-0.5mm

                         1.5 Flexibility: < or = 0.035mm
Multicrystalline                                                           4 million pieces      50.00
Silicon Wafer            2. TECHNICAL PARAMETERS

                         2.1 Resistivity: 0.5 ~ 2 (ohm symbol).cm

                         2.2 Type of electric conduction: Type P

                         2.3 Minority carrier lifetime: > or = 2(u)s

                         2.4 Oxygen concentration: <1x10(18)at/cm(3)
</TABLE>

<PAGE>
               2.5 Carbon concentration: <5x10(17)at/cm(3)

               3. SURFACIAL QUALITY:

               3.1 Notch: notch of crystal orientation on
               any subject silicon wafer shall be no bigger
               than 1x0.3mm, and there shall be no more than
               two notches on any subject
--------------------------------------------------------------------------------

<Table>
<Caption>
--------------------------------------------------------------------------------
NAME OF SUBJECT     TECHNICAL SPECIFICATIONS               QUANTITY  PRETAX UNIT
   PRODUCT                                                              PRICE
                                                                         (RMB
                                                                     YUAN/PIECE)
--------------------------------------------------------------------------------
<S>             <C>                                        <C>        <C>
                silicon wafer.

                3.2 Broken edge: any subject silicon wafer
                does not allow a broken edge bigger than
                1x0.5mm or more than two broken edges.

                3.3 Any subject silicon wafer does not
                allow any crack or conspicuous mark left
                by a knife-cut or pit.

                3.4 The surface of any subject silicon
                wafer does not allow any stain or abnormal
                spot.

--------------------------------------------------------------------------------
                Total Price                                         RMB200 million
--------------------------------------------------------------------------------
</TABLE>

Article 9.     Quality requirements, technical standards and conditions on which
               and term during which the Seller shall be responsible for the
               quality of the subject silicon wafers: as set forth above in this
               Agreement.

Article 10.    Place and manner of delivery: The subject products shall be
               delivered to the warehouse of the Buyer.

Article 11.    Manner and cost of transportation: The subject products hereunder
               shall be delivered to the Buyer by means of road transportation
               at the Seller's expense.

Article 12.    Packaging standards and type of packaging materials: Suitable for
               long-distance transportation.

Article 13.    Standards and method of inspection and period for objection:
               After each delivery of the silicon wafers to the Buyer, the Buyer
               shall before warehousing, conduct full surface inspection of such
               silicon wafers pursuant to the specifications set forth herein.
               Where it has been discovered in the course of such inspection

<PAGE>
               that there is any shortfall in the quantity of such batch of the
               silicon wafers so delivered either due to the inconsistency
               between the delivered quantity and the shipped quantity or the
               breakage of certain silicon wafers, such shortfall, after being
               confirmed by the parties hereto, shall be made up within ten
               days. In addition to that, any serious quality problem that may
               arise in the production process of the subject products shall be
               resolved through consultations between the parties hereto.

Article 14.    Terms of and period for payment: Price for the subject products
               to be supplied hereunder shall be paid as follows:

               (1) For each batch of the subject products to be delivered
               during the period from December 2006 to March 2007, 60% of the
               price for such batch of the subject products shall be deducted
               from the advance payments. In other words, RMB10,710,000 shall be
               deducted each month if the delivery schedule set forth above is
               followed. The remaining 40% of the price shall be paid within 7
               days as of the Buyer's acceptance of such batch of the subject
               products. In other words, RMB 7,140,000 shall be paid each month
               if the delivery schedule set forth above is followed.

               (2) For each batch of the subject products to be delivered
               during the period from April to May in 2007, 60% of the price
               for such batch of the subject products shall be deducted from
               the advance payments. In other words, RMB16,500,000 shall be
               deducted each month if the delivery schedule set forth above is
               followed. The remaining 40% of the price shall be paid within
               7 days as of the Buyer's acceptance of such batch of the subject
               products. In other words, RMB11,000,000 shall be paid each month
               if the delivery schedule set forth above is followed.

               (3) For each batch of the subject products to be delivered during
               the period from June to July in 2007, 60% of the price for such
               batch of the subject products shall be deducted from the advance
               payments and RMB22,500,000 shall be deducted each month if the
               delivery schedule set forth above is followed. The remaining 40%
               of the price for each batch of the subject products delivered
               shall be paid within 7 days as of the Buyer's acceptance of such
               batch of the subject products and RMB15,000,000 shall be paid
               each month if the delivery schedule set forth above is followed.

               Where the advance payment then left is not enough for any
               deduction, the Buyer shall make up the shortfall in a timely
               manner. For the Buyer's payment for each batch of the subject
               products actually delivered, the Seller shall issue to the Buyer
               a VAT invoice in a full amount.

Article 15.    Term of this Agreement. This Agreement shall come into effect
               upon execution and expire upon the full performance hereof.

Article 16.    In the event that either party hereto fails to perform any of
               its obligations hereunder, the non-breaching party may hold the
               breaching party liable for damages arising from such failure.
               Where the quantity of the subject products actually delivered
<PAGE>
               during any month is less than 90% of the agreed quantity, the
               Seller shall pay liquidated damages to the Buyer each day which
               shall be equal to 5% of the total consideration of this
               Agreement. In such case, the Buyer shall have the right to
               terminate this Agreement at its sole discretion and request the
               Seller, within 6 days as of its receipt of the Buyer's notice for
               termination of this Agreement, to refund any and all the paid
               advance payments that are left by then and pay the interest
               accrued thereon at the interest rate of 7 0/00/month for the
               period when such advance payments have been occupied by the
               Seller. In addition to that, the Seller shall pay liquidated
               damages to the Buyer which shall be twice as much as 20% of the
               payment for the subject products that are left unsupplied in such
               month.

Article 17.    Any dispute in connection with the performance of this Agreement
               shall be settled through negotiations between the parties hereto.
               If no settlement can be reached through such negotiations, the
               parties hereto agree that the dispute shall be submitted to
               Shanghai Arbitration Commission for its arbitration.

Article 18.    Miscellaneous. The parties hereto agree that the unit price for
               the 0.35 million pieces of the 125x125 multicrystalline silicon
               wafers delivered during November 2006 shall be determined as RMB
               45.5/piece. Based on the premise that such agreement is
               performed, the unit price of the 0.3392 million pieces of the
               125x125 multicrystalline silicon wafers delivered during October
               2006 shall be determined as RMB 53/piece. The unit price of any
               silicon wafers delivered during November 2006 other than the
               above 0.35 million pieces shall be subject to the unit price set
               forth herein above.

<Table>
<Caption>

--------------------------------------------------------------------------------
               The Seller                                   The Buyer
--------------------------------------------------------------------------------
<S>                                            <C>
Corporate name: Jiangxi LDK Solar Hi-Tech      Corporate name: Jiangsu Linyang
Co., Ltd. (company seal)                       Solarfun Co., Ltd.(company seal)

Address: Xinyu Economic and Technological      Address: 666 Linyang Road,
Development Zone, Jiangxi Province             Qidong, Jiangsu Province

Legal Representative: Zhu Liangbao (signature) Legal Representative: Lu Yonghua
Authorized Agent:                              (signature)
                                               Authorized Agent:
                                                                ----------------

Tel: 0790-6860061
Fax: 0790-6860085                              Tel: 0513-3115763
                                               Fax: 0513-3115763

Bank of Deposit:

                 -------------------           Bank of Deposit: Bank of China,
Account No.:                                   Qidong Branch, Business
             -------------------               Department
Tax No.:                                       Account No.: 647032159808091001
          -------------------                  Tax No.: 320681765140726

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</Table>

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