<PAGE>
                                                                   EXHIBIT 10.35
                                                           [ENGLISH TRANSLATION]
                                                                  Execution Copy


          SUPPLEMENTAL CONTRACT NO. 4 TO THE JOINT VENTURE CONTRACT OF

              BAODING TIANWEI YINGLI NEW ENERGY RESOURCES CO., LTD.


This Contract is signed on September 28, 2007 in Baoding, Hebei, People's
Republic of China

BY AND BETWEEN

(1)  BAODING TIANWEI BAOBIAN ELECTRIC CO., LTD. ("PARTY A"), a company limited
     by shares duly established and validly existing under the laws of the
     People's Republic of China (the "PRC"), with its legal address at No. 28,
     Jing Xiu Street, Baoding, Hebei, and its correspondence address at No.
     2222, West Tian Wei Road, Baoding, Hebei; Tel: 0312-3308511; Fax:
     0312-3230382.

(2)  YINGLI GREEN ENERGY HOLDING COMPANY LIMITED ("PARTY B"), a legal person
     duly established and validly existing under the laws of the Cayman Islands
     and having its legal address at Century Yard, Cricket Square, Hutchins
     Drive, PO Box 2681 GT, George Town Cayman, British West Indies, with its
     correspondence address at No. 3055, Middle Fuxing Road, National High-tech
     Zone, Baoding, Hebei, PRC.

(Party A and Party B are hereinafter collectively referred to as the "PARTIES"
and individually, a "PARTY".)

WHEREAS, as required by the expansion of its business capacity, Baoding Tianwei
Yingli New Energy Resources Co., Ltd. (the "JV COMPANY") proposes to increase
its registered capital;

WHEREAS, Party B has entered into a Term Loan Agreement ("LOAN AGREEMENT") with
the JV Company pursuant to which Party B will extend a loan to the JV Company at
the amount of USD [two hundred and thirty million] (US$230,000,000) and with a
term of eighteen months;

In accordance with the Law of the People's Republic of China on Sino-Foreign
Equity Joint Venture Enterprises and other relevant PRC laws and regulations,
adhering to the principles of equality and mutual benefit and through friendly
consultations, the Parties hereby amend



<PAGE>
the Joint Venture Contract, the Supplemental Contract to the Joint Venture
Contract, the Supplemental Contract No.2 to the Joint Venture Contract, and the
Supplemental Contract No.3 to the Joint Venture Contract (collectively, the "JV
CONTRACT") signed by the Parties on August 25, 2006, October 10, 2006, November
13, 2006, and December 18, 2006 respectively, to reflect the change of the
registered capital.

Unless otherwise defined or specified herein, the terms used in this Contract
shall have the same meanings as ascribed to them under the JV Contract.

I.   Section 5 of the JV Contract is hereby amended as follows:

5.1  TOTAL INVESTMENT

     The amount of the total investment of the JV Company is [nine billion three
     hundred and twenty-eight million three hundred and twenty thousand]
     Renminbi (RMB[9,328,320,000]).

5.2  REGISTERED CAPITAL

     The amount of the registered capital of the JV Company is [three billion
     three hundred and seventy-five million two hundred and twenty thousand]
     Renminbi (RMB[3,375,220,000]).

5.3  CONTRIBUTIONS TO REGISTERED CAPITAL

     Of the total amount of the registered capital, the subscribed amount and
     percentage (the "CONTRIBUTION PERCENTAGE") of capital contribution of each
     Party are as follows:

     (a)  Party A subscribes for forty-nine million Renminbi (RMB49,000,000),
          corresponding to [25.99]% of the equity interest in the JV Company.

     (b)  Party B subscribes for three billion three hundred and twenty-six
          million two hundred and twenty thousand Renminbi (RMB3,326,220,000) in
          equivalent U.S. Dollars, corresponding to [74.01]% of the equity
          interest in the JV Company.

     The Parties have contributed one billion six hundred and twenty-four
     million three hundred and eighty thousand Renminbi (RMB1,624,380,000) to
     the registered capital and the remaining registered capital of one billion
     seven hundred and fifty million eight hundred and forty thousand Renminbi
     (RMB1,750,840,000) shall be contributed by Party B.



<PAGE>
     Both Parties agree that Party B shall contribute to the JV Company [one
     billion seven hundred and fifty million eight hundred and forty thousand]
     Renminbi in equivalent US dollars (the "CAPITAL CONTRIBUTION") within sixty
     (60) days after the approval of this Contract by the Approval Authority.
     Both Parties further agree that, after the approval is obtained from the
     foreign exchange administrative authority, all of the loan principal
     provided by Party B for the JV Company under the Loan Agreement shall be
     converted in equivalent amount into the registered capital of the JV
     Company contributed by Party B, and shall be deemed as part of Party B's
     Capital Contribution.

II.  All other articles and sections of the JV Contract shall remain unchanged.

III. This Contract shall be executed in four (4) originals, and shall become
     effective after it is signed by authorized representatives of both Parties
     and approved by the Approval Authority.


                    [Space below is intentionally left blank]



<PAGE>
IN WITNESS WHEREOF each of the parties hereto has caused this Contract to be
executed by its duly authorised representative on September 28, 2007.



BAODING TIANWEI BAOBIAN ELECRTIC CO., LTD

/s/ Mingjin Yang
-------------------------------------------
Name: Mingjin Yang
Title: General Manager
Nationality: Chinese



YINGLI GREEN ENERGY HOLDING COMPANY LIMITED

/s/ Liansheng Miao
-------------------------------------------
Name: Liansheng Miao
Title: Chairman and Chief Executive Officer
Nationality: Chinese