<PAGE>
                                                                   EXHIBIT 10.38
                                                                     TRANSLATION

            Sichuan Xinguang Silicon Science and Technology Co., Ltd.

               Domestic Sales Contract of Polycrystalline Silicon

Buyer (hereinafter referred to as Party A):
Baoding Tianwei Yingli New Energy Resources Co., Ltd.
Address: 3055 Fuxingzhong Road, Baoding, Hebei
Post code: 071000
Telephone No.: 0312-8929874/8929866
Fax: 0312-8929800

Seller (hereinafter referred to as Party B):
Sichuan Xinguang Silicon Science and Technology Co., Ltd.
Address: 2 Legao Avenue, High & New Technology Development Zone, Leshan
Municipal, Sichuan
Post code: 614000
Telephone No.: 0833-2595387
Fax: 0833-2596408

This agreement is entered into by and between Party A and Party B, through
friendly negotiation in accordance with Contract Law of the People's Republic of
China, as well as other applicable laws and regulations.

I.    Party A agrees to purchase and Party B agrees to sell the polycrystalline
      silicon products manufactured by Party B. Details are as follows:


<Table>
<Caption>

Product Description      Trademark  Specification    Unit  Quantity        Unit Price  Total Price
-------------------      ---------  -------------    ----  --------        ----------  -----------
<S>                      <C>        <C>              <C>   <C>             <C>         <C>
Polycrystalline silicon             Block, 10kg/bag  kg    1,000,000 Tons  [-]*        [-]*

Product parameters       Donor impurity less than or equal to 4.5ppba; acceptor impurity less than
                         or equal to 5.0ppba; specification: block, 0-15mm max 5%, 15-200mm max 95%.
                         the total products include non-washing free silicon materials of 30%

Total price              [-]*

Notes                    The total price of this contract includes value-added tax at 17%
</Table>

II.   Conditions for payment; conditions and date for delivery

----------

*     INFORMATION INTENTIONALLY OMITTED; CONFIDENTIAL TREATMENT HAS BEEN
      REQUESTED FOR SUCH INFORMATION, AND SUCH INFORMATION HAS BEEN SEPARATELY
      FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.

<PAGE>


            1.    Party A shall prepay 5% of total price of this contract,
                  namely [-]*, to Party B within 15 working days of the
                  execution date.

            2.    Party A shall pay 5% of the total price of this contract,
                  namely [-]* to Party B prior to December 31, 2007.

            3.    Party B shall deliver products to Party A batch by batch
                  according to its production status. Party B shall deduct the
                  products price for each batch from the received prepayment,
                  and should also notify Party A in advance for supplemental
                  payment in the event the prepayment is not adequate. Party B
                  shall continue to deliver products upon receipt of the
                  supplemental payment from Party A. The specific quantity and
                  date of each delivery shall be solely decided by Party B,
                  provided the monthly delivery shall be no less than 30 ton.
                  This contract shall be completely closed within 2008.

            4.    The product price of this contract shall remain fixed, if the
                  market price at consignment fluctuates within the scope
                  from-5% to +5% to [-]*/kg; While the product price shall be
                  determined through further negotiation, in the event the
                  market price goes beyond the same scope.

            5.    This contract shall be suspended in the event any party put
                  forward a writing proposal for adjustment, and will be resumed
                  after the mutual consent is achieved through negotiation.

III.  Transportation, packaging and the location for delivery

            1.    Party B shall be responsible for transporting products to the
                  location stipulated herein at its own freight and insurance.

            2.    Packaging criteria: to be determined by Party B, as well as
                  satisfying the requirements herein for products.

            3.    Location for delivery: plant area of Baoding Tianwei Yingli
                  New Energy Resources Co., Ltd.

            4.    Manner for delivery: Party B shall notify Party A for the
                  consignment date and the prospective date of arrival at the
                  stipulated location by 1-working-day prior notice. Party A and
                  Party B or the entrusted transportation agent of Party B shall
                  together complete the acceptance and delivery procedure at the
                  delivery location.

----------

*     INFORMATION INTENTIONALLY OMITTED; CONFIDENTIAL TREATMENT HAS BEEN
      REQUESTED FOR SUCH INFORMATION, AND SUCH INFORMATION HAS BEEN SEPARATELY
      FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.


<PAGE>

IV.   Acceptance method

            1.    The varieties, quantities, quality and packaging criteria set
                  forth in this contract shall be taken as acceptance standard.

            2.    An acceptance test shall be conducted with respect to the
                  brand, quantity, type, specification by Party A within 15 days
                  of delivery. Party A will be assumed no demurrer on the
                  delivered product in the event no acceptance test is made
                  within 10 working days of delivery, Otherwise the notice for
                  demurrer shall be sent to Party B in writing within 10 days.

            3.    The delivered product shall be further examined by relevant
                  authorities in accordance with the quality standard set forth
                  in this contract, in the event any dispute arises out of the
                  acceptance.

V.    Risks on damages or lost of products

            1.    The risks shall be assumed by Party B prior to delivery, and
                  shall be transferred to Party A upon delivery.

VI.   Any Party falls in default of performance due to wars, earthquakes, flood,
      fire or storm will not be liable for breach of contract. Such Party,
      however, should notify the counterparty forthwith for the details of force
      majeure through fax, and provide a notarial deed from the local notary
      through registered airmail within 15 days.

VII.  It is agreed by both parties that any commercial secrets of one party
      acquired through execution and performance of this contract by the other
      may not be disclosed or unjustly used. Any party shall be liable for the
      damages arising from its disclosure or unjust use of such commercial
      secrets suffered by the other.

VIII. It is agreed that any further contracts between both parties (including
      without limitation agreements and memorandums) or the alteration and
      supplementation thereto shall be conducted in writing and deemed as
      inseparable part of this contract, since the execution hereof.

IX.   Any disputes arising out of this contract shall be settled through
      negotiations by both parties, or submitted to Chengdu Arbitration
      Committee in the event no mutual consent could be achieved.

X.    The date when the later party signs on this contract shall be taken as the
      execution date hereof. The execution place shall be High & New Technology
      Development Zone, Leshan, Sichuan.

XI.   This Contract shall be executed in quadruplication. Each party will hold 2
      copies with equal legal effect. This contract shall take effect upon
      execution by the two parties or their authorized representatives with
      respective common seal or contract seal.


<PAGE>




Party A: Baoding Tianwei Yingli New Energy Resources Co., Ltd.

/s/ Liansheng Miao
------------------
Legal representative or authorized representative

October 19, 2007
----------------
Execution date

Party B: Sichuan Xinguang Silicon Science and Technology Co., Ltd.

/s/ Shaozhang Chen
------------------
Legal representative or authorized representative

October 6, 2007
---------------
Execution date

<PAGE>



                             Supplemental Agreement

Buyer: Baoding Tianwei Yingli New Energy Resources Co., Ltd.
Seller: Sichuan Xinguang Silicon Science and Technology Co., Ltd.

The Buyer and Seller, through friendly negotiation, agree as follows on October
29, 2007:

I. The purchase contract (contract number: XG-SALE (SI)-07-22), entered into by
both parties on October 19, 2007, indicated in article 2(4):

"The product price of this contract shall remain unchanged, if the market price
at consignment fluctuates within the scope from-5% to +5% to [-]*/kg; while the
product price shall be determined through further negotiation, in the event the
market price goes beyond the same scope."

To avoid any ambiguity of the original contract, both parties hereby agree,
through friendly negotiation, to amend the above referenced article to read as
follows:

"The product price of this contract shall remain unchanged, if the market price
at consignment fluctuates within the scope from -5% to +5% to the price at
execution of this contract; while the product price shall be determined through
further negotiation, in the event the market price goes beyond the same scope"

II. The articles for providing 1,000 ton washing-free solar grade silicon in the
purchase contract (contract number: "YLXG070418" and "the supplemental
agreement" thereto), entered into by both parties on April 10, 2007, shall be
superseded by the domestic sales contract for polycrystalline silicon (contract
number: "XG-SALE (SI)-07-22") entered into on October 19, 2007 and this
supplemental agreement.

Buyer: Baoding Tianwei Yingli New Energy Resources Co., Ltd.
Representative: /s/Liansheng Miao
                ------------------
Title:
Address: 3055 Fuxingzhong Road, Baoding, Hebei


Seller: Sichuan Xinguang Silicon Science and Technology Co., Ltd.
Representative: /s/ Shaozhang Chen
                ------------------
Title:
Address: High & New Technology Development Zone, Leshan, Sichuan


----------

*     INFORMATION INTENTIONALLY OMITTED; CONFIDENTIAL TREATMENT HAS BEEN
      REQUESTED FOR SUCH INFORMATION, AND SUCH INFORMATION HAS BEEN SEPARATELY
      FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.
<PAGE>
                                                Contract No.: XG-SALE (SI)-07-07

            Sichuan Xinguang Silicon Science and Technology Co., Ltd

               Domestic Sales Contract of Polycrystalline Silicon

Buyer (hereinafter referred to as Party A):
Baoding Tianwei Yingli New Energy Resources Co., Ltd.
Address: 3055 Fuxingzhong Road, Baoding, Hebei

Party B (hereinafter referred to as Party B):
Sichuan Xinguang Silicon Science and Technology Co., Ltd.
Address: 2 Legao Avenue, High & New Technology Development Zone,
Leshan Municipal

Date of Execution: July 5, 2007

Party A and Party B hereby enter into this contract (this "Contract") through
friendly negotiation in accordance with the Contract Law of People's Republic of
China, in Leshan, Sichuan Province.

I. Product description, specification, quantity, unit price and total price:

<TABLE>
<CAPTION>
Product Description      Trademark  Specification      Unit  Quantity          Unit Price (per kilogram)  Total Value
-------------------      ---------  -------------      ----  --------          -------------------------  -----------
<S>                      <C>        <C>                <C>   <C>               <C>                        <C>
Polycrystalline Silicon             Parameters:        kg    182 ton (to be    [-]*                       [-]* (to be calculated
                                    phosphorus               determined by                                on the basis of actual
                                    <=4.5 ppba               the quantity                                 quantity for consignment)
                                    Boron                    for consignment)
                                    <= 5.0 ppba

                                    90% washing free
                                    material; 10% non
                                    washing-free
                                    material
                                    Block:
                                    <=450mm

Total price(in words): [-]*

Notes: value-added tax included at a rate of 17% in the total price
</TABLE>

II. Warranty for the product quality

----------
*     INFORMATION INTENTIONALLY OMITTED; CONFIDENTIAL TREATMENT HAS BEEN
      REQUESTED FOR SUCH INFORMATION, AND SUCH INFORMATION HAS BEEN SEPARATELY
      FILED WITH THE SECURITIES AND EXCHANGE COMMISSION.

<PAGE>

                                                                               2

      The product provided by the seller is warranted fully new, unused and
produced by the seller. The quality of the product shall meet the sellers'
Quality Inspection Criterion and the criterion of quality, specification and
capability stipulated herein.

      The buyer shall be entitled to decline the goods in case of quality
discrepancy, and also be entitled to reject the products if finding the product
quality doesn't meet the requirements hereof after receipt.

III. Conditions and date for delivery:

      Party A shall pay 100% price of this agreement in advance. The products
herein shall be sent out within 15 days after total price is paid into the
bank account designated by Party B, and shall further be delivered to the
location designated by Party A within 30 days thereafter.

      The implementation of this contract shall be commenced from the date of
execution, and shall be completed within 9 months of the execution date.

IV. Transportation, packaging and location for delivery

      1.    Party B shall be responsible for transporting products to the
            location stipulated herein at its own freight and insurance.

      2.    Packaging criteria: to be determined by Party B, as well as
            satisfying the requirements herein for products.

      3.    Location for delivery: plant area of Baoding Tianwei Yingli New
            Energy Resources Co., Ltd.

      4.    Manner for delivery: Party B shall notify Party A for the
            consignment date and the prospective date of arrival at the
            stipulated location by 1-working-day prior notice. Party A and Party
            B or the entrusted transportation agent of Party B shall together
            complete the acceptance and delivery procedure at the delivery
            location.

V. Inspection prior to consignment

      1.    The seller shall conduct examination prior to delivery with respect
            to the quality, specification and quantity of the product, and
            produce a report for products examination. The report shall include
            the quality criteria of the product, technical parameter and
            examination result.

      2.    The seller shall provide the examination report at delivery, and
            both parties will do examination and approval on the quantity and
            package. The examination for internal quality shall be made by Party
            A after acceptance.


<PAGE>

                                                                               3

      3.    Party A shall be entitled to inquire about and examine on the
            production, packaging, transportation, etc. under this contract.

VI. Acceptance method

      1.    The product specification, original manufacturer, quantity, quality
            and packaging criteria shall be taken as the acceptance criteria.
            The examination report provided by the seller shall be deemed as
            part of the examination criteria.

      2.    An acceptance test shall be conducted with respect to the brand,
            quantity, type, specification by Party A within 5 working days of
            delivery. Party A will be assumed no demurrer on the delivered
            product in the event no acceptance test is made within 5 working
            days of delivery.

      3.    Acceptance method: sampling examination. Party A will be assumed no
            demurrer on the delivered product in the event no acceptance test is
            made within 5 working days of delivery. Otherwise the notice for
            demurrer shall be sent to Party B in writing within 5 working days.

      4.    The delivered product shall be further examined by relevant
            authorities in accordance with the quality standard set forth in
            this contract, in the event any dispute arises out of the
            acceptance.

VII. Risk on damages and lost of products

      The risks shall be assumed by Party B prior to delivery, and shall be
transferred to Party A upon delivery.

VIII. Settlement method and term

      1.    Advance payment: The Bank shall be designated by the seller, and the
            seller shall inform the buyer for the name and number of the account
            in writing.

      2.    In case of any changes with respect to the receiving bank, the
            account name or account number, the seller shall inform the buyer in
            writing three days prior to the expiration of payment term. The
            seller shall be responsible for any and all losses attributed to the
            default notice or false notice by Party A.

            The two parties agree to take the actual quantity at consignment for
            the basis of the final settlement for total price.

IX Disposal on discrepancy between contracted quantity and actual delivered
quantity

      It is mutually agreed that the actual delivery quantity shall be the
payable quantity for final settlement.

X Disposal on discrepancy between the prepayment by Party A and the actual
balanced amount

<PAGE>

                                                                               4

      In case the advance payment is more than the actual amount, before
receiving of written demurrer by the buyer, the seller may deem the extra amount
of money as the advance payment of next purchase. (The purchase price shall be
determined by next contract) The buyer shall send out written notification
claiming for the extra payment, while the seller shall pay back the extra
payment without interest to the buyer within 15 working days upon receipt of the
notice.

      In case the advance payment is less than the actual amount, the buyer
shall pay the remaining part within 5 working days after receiving the products.
The buyer shall pay to the seller the amount of 0.03% of the unpaid amount daily
after the date of expiration if the buyer fails to pay on schedule.

XI The buyer shall provide the seller with the feedback report with respect to
the overseas use and relevant parameters of polishing

XII Force Majeure

      Any Party falls in default of performance due to wars, earthquakes, flood,
fire or storm will not be liable for breach of contract. Such Party, however,
should notify the counterparty forthwith for the details of force majeure
through fax, and provide a notarial deed from the local notary through
registered airmail within 10 days.

      Both parties shall make full endeavor to implement the contract.

XIII It is mutually agreed that in the course of concluding a contract, any
party shall be liable for the damages incurred to the other by the following
conductions:

      1. negotiating in bad faith under the pretext of concluding a contract:

      2. intentionally concealing a material fact relating to the conclusion of
the contract or supplying false information:

      3. any other activities which violates the principle of good faith.

XIV It is agreed by both parties that any commercial secrets of one party
acquired through execution and performance of this contract by the other may not
be disclosed or unjustly used. Any party shall be liable for the damages arising
out its disclosure or unjust use of such commercial secrets suffered by the
other.

XV Any disputes arising out of this contract shall be settled through
negotiations by both parties, or submitted to Chengdu Arbitration Committee in
the event no mutual consent could be achieved.

XVI The original copy of this contract shall not be altered. Any delete or
amendment shall lead to cancellation of the contract. In case of delete or
amendment, only the original copy which has not been altered shall be effective.


XVII It is agreed that any further contracts between both parties (including
without limitation agreements and memorandums) or the alteration and
supplementation thereto shall

<PAGE>

                                                                               5

be conducted in writing and deemed as inseparable part of this contract, since
the execution hereof.

XVIII The execution location of this contract shall be Leshan, Sichuan
Province.

XIX The date when the later party signs on this contract shall be taken as the
execution date.

XX This Contract shall be executed in 6 copies. Each party will hold 3 copies
with equal legal effect. This contract shall take effect upon execution by the
two parties or their authorized representatives with respective common seal or
contract seal.


XXI Both parities may sign and seal the contract once agreement has been
achieved. In order to improve the efficiency, the party completing signing and
sealing may fax the contract to the other party, and after the other party
finishes the procedure, the contract takes into effect.

      The party which signs first shall mail 4 original copies to the other
party, the other party shall keep 3 copies and mail the other three copies and
the first mutually recognized copy back to the first party.

      Any party shall inform the other party in writing in case of changes of
address or telephone number. Notice sent out by a party to the other party at
the address set forth below shall be deemed to be validly sent absent any
notice of change of address from the other party.

<TABLE>
<S>            <C>                         <C>          <C>
Purchaser:     Baoding Tianwei Yingli New
               Energy Resources Co., Ltd.

Address:       3055 Fuxingzhong Road,
               Baoding, Hebei

Post code:

Telephone:     0312-8929874

Fax:           0312-8929800

Seller:        Sichuan Xinguang Silicon
               Science and Technology
               Co., Ltd.

Address:       No. 2 Legao Avenue,
               Leshan
               High & New Technology
               Development
               Zone, Leshan Municipal

Post code:     614000

Telephone:     0833-2595387

Fax:           0833-2596408

Party A:       Baoding Tianwei Yingli      Party B:     Sichuan Xinguang
               New Energy Resources                     Silicon Science and
               Co., Ltd. (Seal)                         Technology Co., Ltd. (Seal)
Legal          /s/ Liansheng Miao          Legal        /s/ Shaozhang Chen
representative:                            representative:

Date: September 5, 2007                    Date: July 2, 2007
</TABLE>