<PAGE>
                                                                 EXHIBIT 10.37

SUPPLY AGREEMENT

between           Wacker Chemie AG
                  Hanns-Seidel-Platz 4
                  81737 Munich
                  Federal Republic of Germany

                  - hereinafter referred to as "WACKER" -

and               Tianwei Yingli New Energy Resources Co.Ltd
                  No. 3055 Middle Fuxing Road
                  Bao Ding City
                  P.R.China (071051)

                  - hereinafter referred to as "BUYER" -

PREAMBLE

BUYER has requirements for polycrystalline Silicon. WACKER is willing to
supply BUYER with polycrystalline Silicon.

Now, therefore, in consideration of the foregoing and the mutual premises
hereinafter contained, WACKER and BUYER agree as follows:

1.    PRODUCT

WACKER agrees to sell and deliver and BUYER agrees to purchase and take the
polycrystalline Silicon manufactured by WACKER as defined per specification
set forth in APPENDIX A (hereinafter referred to as "PRODUCT").

2.    QUANTITIES

2.1   The BUYER shall make the agreed prepayment according to the payment
      schedule set forth in APPENDIX A.

      WACKER shall sell and deliver to BUYER and BUYER will purchase and take
      from WACKER the annual quantities of PRODUCT set forth in APPENDIX A.

3.    PRICES / PAYMENT TERMS

3.1   The prices for the PRODUCT are set forth in APPENDIX A.

3.2   The prices under Section 3.1 above shall be firm until 31.12.2011 and
      only subject to change, if the relevant energy price index, defined in
      APPENDIX C, increases or decreases by more than 20%. The agreed prices
      will be adjusted by the rate (Euro/kg) as specified in the table in
      APPENDIX C.
<PAGE>
                                                                               2


3.3   WACKER shall invoice BUYER with each shipment of PRODUCT. BUYER shall
      pay such invoices net within [-]* ([-]*) days from the date of such
      invoices.

4.    DELIVERY

4.1   PRODUCT shall be delivered FOB German seaport (Incoterms 2000).

4.2   All deliveries of PRODUCT are subject to WACKER's General Conditions of
      Sale set forth in APPENDIX B and hereby made part of this Agreement,
      provided, however, that if there is any conflict between the terms of
      this Agreement and the said Conditions of Sale the terms of this
      Agreement shall prevail.

4.3   The agreed annual quantities for the years 2009, 2010 and 2011 will be
      shipped in about equal monthly installments.

5.    QUALITY / INSPECTION AND TESTING

5.1   The PRODUCT supplied by WACKER shall conform to the specifications set
      forth in APPENDIX A.

5.2   It is understood and expressly agreed that the PRODUCT delivered by
      WACKER hereunder are PRODUCTS of technical quality only and BUYER is
      exclusively responsible for fitness for purpose, handling, use and
      application of the PRODUCT.

5.3   Upon receipt of each shipment of PRODUCT BUYER shall inspect the
      PRODUCT. Unless BUYER notifies WACKER within [-]* ([-]*) days after the
      arrival of the shipment at Buyer's premises or warehouse, that it does
      not conform to the quantity ordered or WACKER's certificate of quality
      does not conform to the specifications set forth in APPENDIX A, said
      shipment shall be deemed to have been delivered as ordered and WACKER's
      certificate of quality shall be deemed to conform to the specifications.

6.    WARRANTY / LIABILITY

6.1   WACKER warrants solely that the PRODUCT delivered shall conform to the
      specifications set forth in APPENDIX A. Except for the warranty
      provided above, WACKER disclaims any and all other express or implied
      warranties with respect to the PRODUCT, and any warranty of
      merchantability or fitness for a particular purpose is expressly
      disclaimed.

6.2   BUYER's exclusive remedy and WACKER's sole obligation for any claim or
      cause of action arising under this Agreement because of defective
      PRODUCT is expressly limited to either (i) the replacement of
      non-conforming PRODUCT or the repayment of the purchase price of the
      respective quantity of PRODUCT; OR (ii) payment not to exceed the
      purchase price of the specific quantity of PRODUCT for which damages
      are claimed.

----------
*    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>
                                                                               3


      Any remedy is subject to BUYER giving WACKER notice as provided for in
      Section 5.3.

6.3   The parties agree that the remedies provided in this Agreement are
      adequate and that except as provided for above, neither party shall be
      liable to the other, whether directly or by way of indemnity or
      contribution for special, incidental, consequential or other damages
      arising from the breach of any obligation hereunder or for any other
      reason whatsoever, including actions for tort, strict or product
      liability, patent or trademark infringement except as provided for
      herein.

7.    CONFIDENTIALITY

7.1   BUYER may use all the information disclosed by WACKER under this
      Agreement only for the purposes contemplated herein.

7.2   BUYER agrees to keep secret such information and to take the necessary
      measures to prevent any disclosure to third parties.

7.3   BUYER is responsible for assuring that secrecy is maintained by its
      employees and agents.

7.4   The secrecy obligation does not apply to information

      -  where BUYER can prove that is or was known to BUYER prior to its
         receipt;

      -  which is or has become generally available to the public prior to
         its receipt;

      -  which is or has become generally available to the public without
         being the result of a breach of this Agreement;

      -  which is in accordance with information BUYER received or got access
         to from an entitled person without any obligation of secrecy;

      -  where WACKER approved the disclosure in a particular case in writing.

7.5   The secrecy obligation shall survive the term of this Agreement.

8.    SECURITY INTEREST

      BUYER hereby grants WACKER a continuing security interest in any
      PRODUCT and in the proceeds (including proceeds of sale or insurance)
      until the entire purchase price for the PRODUCT currently or previously
      sold to BUYER is paid and until all late payment interest, legal fees
      and expenses required to enforce WACKER's rights and any costs,
      expenses, taxes or other charges required to be paid by BUYER to WACKER
      have been paid in full. BUYER specifically agrees that WACKER may file
      one or more financing statements or other documents and take all
      necessary or appropriate in order to create, perfect, preserve or
      enforce WACKER's security interest in the PRODUCT pursuant to the
      Uniform Commercial Code and other applicable law, and hereby grants to
      WACKER a power of attorney to execute such statements or documents in
      BUYER's name. WACKER's reasonable costs and expenses (including, but
      not limited to, attorney's fees and expenses for pursuing, searching
      for, receiving, taking, keeping, storing, advertising and selling the
      PRODUCT shall be paid by BUYER who shall remain liable for any

<PAGE>
                                                                               4


      deficiency resulting from a sale of the PRODUCT and shall pay any
      deficiency forthwith on demand. The requirement of reasonable notice of
      sale shall be met if such notice is mailed and addressed to BUYER at
      its last address appearing on WACKER's records at least 30 days prior
      to the date of sale.

9.    FORCE MAJEURE

9.1   If either party should be prevented or restricted directly or
      indirectly by an event of Force Majeure as hereinafter defined from
      performing all or any of its obligations under this Agreement, the
      party so affected will be relieved of performance of its obligations
      hereunder during the period that such event and its consequences will
      continue, but only to the extent so prevented, and will not be liable
      for any delay or failure in the performance or any of its obligations
      hereunder or loss or damage whether direct, general, special or
      consequential which the other party may suffer due to or resulting from
      such delay or failure, provided always that prompt notice is given by
      the affected party to the unaffected party by facsimile or telephone of
      the occurrence of the event constituting the Force Majeure, together
      with details thereof and an estimate of the period of time for which it
      will continue.

9.2   The term Force Majeure shall include without limitation strike, labor
      dispute, lock out, fire, explosion, flood, war (accident), act of god
      or any other cause beyond the reasonable control of the affected party,
      whether similar or dissimilar to the causes enumerated above.

10.   ASSIGNMENT

      This Agreement or any part thereof is not assignable by either party
      without the prior written consent of the other party.

11.   ENTIRE AGREEMENT

11.1  This Agreement constitutes the whole agreement between the parties as
      to the subject matter thereof and no agreements, representations or
      warranties between the parties other than those set out herein are
      binding on the parties.

11.2  No waiver, alteration, or modification of this Agreement shall be valid
      unless made in writing and signed by authorized representatives of the
      parties.

12.   SEVERABILITY

      In the event, any provision of this Agreement shall be declared
      invalid, illegal or unenforceable, the validity, legality and
      enforceability of the remaining provisions shall not in any way be
      affected or impaired thereby.

13.   HEADINGS

      The headings of the articles of this Agreement are inserted for
      convenience only and shall not be deemed to constitute a part of this
      Agreement or to affect the construction hereof.
<PAGE>
                                                                               5


14.   DURATION / TERMINATION

14.1  This Agreement will commence on the 01.10.2007 and will endure for a
      defined period of 4 (four) years and 3(three) month.

15.   APPLICABLE LAW / JURISDICTION

      This Agreement shall be construed and the legal relations between the
      parties hereto shall be determined in accordance with the laws of
      Germany; the application of the 1980 United Nations Convention on
      Contracts for the International Sale of Goods is expressly excluded.

      Exclusive place of jurisdiction shall be Munich.



<TABLE>
<S>                    <C>                           <C>
Wacker Chemie AG                                     Tianwei Yingli New Energy Resources Co. Ltd
WACKER POLYSILICON

Date: September 3, 2007                              September 5, 2007

/s/ Ewald Schindlbeck   /s/ Reimund Huber             /s/ Liansheng Miao
--------------------------------------------------   -------------------------------------------
Ewald Schindlbeck      Reimund Huber
President              Director Marketing & Sales
</TABLE>

<PAGE>
                                                                      6


APPENDIX A

SOLARQRADE POLYSILICON

SPECIFICATION PCL-NCS (B)


<Table>
<Caption>
                                                      Price    EURO/kg
Calendar year               Annual quantity (kg)      FOB German Seaport
<S>                         <C>                        <C>
2009                        [-]*                       [-]*
2010                        [-]*                       [-]*
2011                        [-]*                       [-]*
</Table>

PREPAYMENT SCHEDULE

The BUYER will prepay the amount of [-]* Euro/kg for the total above agreed
contract quantity. The invoices, regarding deliveries up to the annual agreed
quantity, will be reduced by  [-]* Euro/kg with each shipment. So WACKER's
invoice will state the above agreed prices on the invoice, but will make
note, that the BUYER has only to pay the invoice amount reduced by  [-]*
Euro/kg.

Regarding to the agreed annual quantities the total prepayment amount of Euro
[-]* ([-]*) has to be paid according to the following schedule on the account
of Wacker Chemie AG:

October 30th, 2007      Euro [-]* ([-]*)

In case the BUYER does fail to take the full amount of the agreed annual
quantity in one respective calendar year, WACKER does not have to repay the
not absorbed outstanding prepayment (regarding the respective calendar year),
BUYER also doesn't have the right to set this prepayment against deliveries
of the following year.

----------
*    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>
                                                                               7


APPENDIX B

GENERAL CONDITIONS OF SALE

1.    GENERALLY:

All our supplies and services as well as all contracts concluded with us are
exclusively subject to the following conditions of sale.  Terms of the
Purchaser which contradict or which deviate from our sales terms and which
are not expressly recognised by us are not valid even if we do not expressly
object to them.  Where a continuing business relationship exists, all future
contracts, supplies and services are also subject to our conditions of sale.

2.    OFFER, CONCLUSION OF CONTRACT:

Our offers are subject to change and non-binding.  Orders are only valid if
confirmed by us in writing or if recognised by us through the act of
delivery.  Any additional verbal agreements, supplements and modifications
are also only valid if confirmed in writing.

3.    DELIVERY, DEFAULT:

3.1   Unless otherwise agreed, any dates quoted for delivery are non-binding.

3.2   We are entitled to make partial deliveries as far as the Purchaser must
      reasonably accept this in the circumstances of an individual case.  The
      corresponding invoices issued are payable without regard to whether
      complete delivery has been made.

3.3   In the event delivery is delayed, the Purchaser may set us a reasonable
      grace period with the notice that he rejects the acceptance of the
      delivery item after expiry of the grace period.  After the expiry of
      the grace period, the Purchaser is entitled to cancel the contract of
      sale through written notice or to request damages instead of
      performance.

      At our request the Purchaser is obligated to state within a reasonable
      period whether he cancels the contract due to delay in delivery, seeks
      damages instead of performance or insists on performance.

3.4   Our liability is set forth in para. 9.  Furthermore in the event of
      slight negligence, our liability is limited to the invoice value of the
      respective delivery item.

4.    RETURN OF LOAN PACKAGING:

In the event of delayed return (meaning in the event normal uploading times
are exceeded) of loading equipment, loading banks and other loan packaging we
reserve the right to charge the Purchaser for the costs incurred by us.

5.    PRICES:

5.1   Unless otherwise expressly agreed, prices are quoted "ex works"
      excluding packaging and plus delivery and shipping costs as well as
      plus any applicable Value Added Tax.
<PAGE>
                                                                               8


5.2   The prices valid on the day of dispatch shall apply.

Should the latter be higher than the contractual price, the Purchaser is
entitled to cancel the contract with regard to the quantities still to be
delivered.  Cancellation shall be made within 14 days after notification of
said price increase.

6.    PAYMENT:

6.1   The payment shall be made in Euro to one of our bank accounts indicated
      on the reverse side.

6.2   Should Purchaser be in arrears with payment, interest for default shall
      be due and payable at 12%, but at least 8% above the respective base
      interest rate.  We reserve the right to claim further damages.  If the
      interest we claim is higher than the statutory interest for delayed
      payment, the Purchaser has the right to demonstrate lower damages just
      as we have the right to show that greater damages were incurred.

6.3   Should Purchaser be in arrears with payment or should there be
      reasonable doubts as to Purchaser's solvency or credit rating, we are
      -- without prejudice to our other rights -- entitled to require payment
      in advance for deliveries not yet made, and to require immediate
      payment of all our claims arising from the business relation.

6.4   Bills of exchange and cheques shall be accepted upon separate agreement
      and only by way of payment.  All expenses incurred in this regard shall
      be borne by the Purchaser.

6.5   Only uncontested or legally proved claims shall entitle the Purchaser
      to set-off or withhold payment.

7.    FORCE MAJEURE:

Events of Force Majeure, in particular strikes, lock outs, operation or
transport interruptions, including at our suppliers, shall suspend the
contractual obligations of each party for the period of the disturbance and
to the extent of its effects.  Should the delays caused exceed a period of 6
weeks, both parties shall be entitled to cancel the contract, with respect to
the contractual performance affected by such delays.  No other claims exist.

8.    QUALITY:

8.1   All our data, especially data relating to product suitability,
      processing and use, as well as to technical support, have been compiled
      to the best of our knowledge.  The Purchaser, however, must still
      perform his own inspections and preliminary trials.

8.2   The Purchaser undertakes to examine the goods immediately after
      delivery with respect to any defects concerning quality and suitability
      of purpose and object to ascertainable defects.  Sample testing shall
      also be performed if this can be reasonably expected of the Purchaser.
      Failure to proceed in aforesaid manner shall result in the goods being
      regarded as accepted.
<PAGE>
                                                                               9


8.3   Complaints must be made within 8 days after receipt of the goods.  In
      case of hidden faults, however, complaints are to be made immediately
      on discovery, within one year after receipt at the very latest.  Said
      claims shall only be taken into consideration if and when made in
      writing and with the relevant documentation attached.  To comply with
      the time limit it shall be sufficient if the complaint is sent in good
      time.

8.4   We are not liable on the basis of public statements by us, the
      manufacturer or his agents, if we were not aware of the statement or
      were not required to have knowledge thereof, the statement was already
      corrected at the time of the purchase decision or the Purchaser cannot
      show that the statement influenced his purchase decision.

8.5   We are not liable for defects which only marginally reduce the value or
      the suitability of the object.  A marginal defect exists in particular
      if the defect can be removed by the Purchaser himself with
      insignificant effort.

8.6   If the Purchaser requests replacement performance due to a defect, we
      may choose whether we remove the defect ourselves or deliver a
      defect-free object as a replacement.  The right to reduce the price or
      cancel the contract in the event of unsuccessful replacement
      performance shall remain unaffected.

8.7   Where complaints are justified, the goods may only be returned to us at
      our expense if after we receive notice of the defect we do not offer to
      collect or dispose of the goods.

8.8   If increased costs arise because the Purchaser has transferred the
      goods to a place other than his commercial place of business, we shall
      charge the Purchaser for the increased costs in connection with the
      remedying of the defect, unless the transfer corresponds to the
      designated use of the object.

8.9   Damage and claims for reimbursement of expenses shall remain unaffected
      as far as not excluded by para. 9.

8.10  All claims due to a defect are subject to a limitation period of one
      year after delivery of the object.  No warranty is made for used
      objects.  The statutory limitation period for objects which are used
      for a building structure in accordance with their usual manner of use,
      and which cause the defectiveness thereof, shall remain unaffected.

8.11  The rights of the Purchaser under Sections 478, 479 German Civil Code
      remain unaffected.

9.    LIABILITY:

Our liability is excluded, regardless of the legal grounds.

This shall not apply in the event of intentional actions or gross negligence
by us or our legal representatives or agents or in the event of breach of
material contractual duties.

In the event of a slightly negligent breach of material contractual duties,
our liability is limited to twice the invoice value of the respective
delivery item.  For damages due to delayed performance para. 3.4 shall also
apply.  Our liability for damages due to injury to life, the body or health,
the
<PAGE>
                                                                              10


liability based on a guarantee and under mandatory statutory provisions, in
particular the Product Liability Act, remain unaffected.

10.   RESERVATION OF OWNERSHIP:

10.1  The goods that have been sold remain our sole property until all
      outstanding debts arising from the business connection with the
      Purchaser have been paid in full.  The Purchaser has power of disposal
      of the purchased goods in the ordinary course of business, or he may
      process the goods until revocation by us.

10.2  Reservation of ownership and power of disposal, as laid down in clause
      10.1, also apply to the full value of the manufactured goods produced
      by processing, mixing and blending or combining our goods.  In each
      case we qualify as the manufacturer.  In cases where the goods are
      processed, mixed and blended or combined with those of a third party,
      and where the reservation of the latter continues to apply, then we
      acquire joint ownership in proportion to the invoice value of those
      processed goods.  If security rights of a third party are in fact or in
      law below that share, the difference will be to our benefit.

10.3  If the Purchaser resells our goods to third parties he hereby assigns
      the entire resulting payment claim -- or in the amount of our joint
      share therein (see para. 10.2) -- to us.  In the event the parties
      agree on a current account, the respective balance amounts shall be
      assigned.  However, the Purchaser shall be entitled to collect such
      payment claim on our behalf until we revoke such right or until his
      payments are discontinued.  The Purchaser is only authorized to make
      assignment of these claims -- even only for the purpose of collection
      by way of factoring -- with our express written consent.

10.4  The Purchaser shall immediately give notice to us if any third party
      raises any claim with respect to such goods or claims which are owned
      by us.

10.5  If the value of the collateral exceeds our accounts receivable by more
      than 20% then we will release collateral on demand and at our
      discretion.

10.6  We are also entitled to take back goods on the basis of the reservation
      of title, even if we have not previously cancelled the contract.  If
      products are taken back by way of the exercise of the reservation of
      ownership, this shall not constitute cancellation of the contract.

10.7  If the laws of the country in which the goods are located after
      delivery do not permit the Vendor to retain the title to said goods,
      but allow the retention of other similar rights to the delivery item,
      the Purchaser shall provide us with such other equivalent right.  The
      Purchaser undertakes to assist us in the fulfilment of any form
      requirements necessary for such purpose.

11.   PLACE OF FULFILMENT, APPLICABLE LAW AND JURISDICTION:

11.1  The originating point of the goods shall, in each case, be the place of
      fulfilment for the delivery.  Munich shall be the place of fulfilment
      for payment.
<PAGE>
                                                                              11


11.2  Exclusively the laws of the Federal Republic of Germany shall apply
      between the parties.  The application of the 1980 United Nations
      Convention on Contracts for the International Sale of Goods is
      expressly excluded.

11.3  If the Purchaser is a merchant or does not have a general place of
      jurisdiction in Germany, the place of jurisdiction is Munich.  We
      shall, however, have the right to also bring a claim against the
      Purchaser at his general place of jurisdiction.

Munich, 15th May 2002
<PAGE>
                                                                              12


APPENDIX C, PAGE 1 OF 2

Relevant Energy Price Index:

"BAFA Grenzubergangspreis" for natural gas

Source:


http://www.bmwi.de/BMWi/Navigation/Energie/Energiestatistiken/energiestatistiken
,did=53736.html

Evaluation periods:
-- Arithmetic mean value out of 6 months
-- April to September for price adjustment of 1st half of the following year
-- October to March for price adjustment of 2nd half of year
-- Basis evaluation period: April 2006 -- September 2006

Price Adjustment Table:

CB ... Index value of Basis evaluation period
CN ... Index value of New evaluation period


<TABLE>
<CAPTION>
                            Price Adjustment
CN/CB (%)                   EURO / kg
---------                   ---------
<S>                         <C>
< - 60 %                    [-]*

< - 40 %                    [-]*

< - 20 %                    [-]*

> + 20 %                    [-]*

> + 40 %                    [-]*

> + 60 %                    [-]*

> + 80%                     [-]*

etc.                        etc.
</TABLE>

On the following example for the calculation of the price adjustment the
procedure is explained in more detail.

----------
*    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>
                                                                              13


APPENDIX C, PAGE 2 OF 2

EXAMPLE FOR CALCULATION OF PRICE ADJUSTMENT

                                   (FLOWCHART)