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                                                                  Exhibit 4.21

             JOINDER AND FIRST AMENDMENT TO STOCKHOLDERS AGREEMENT

     This Joinder and First Amendment to Stockholders Agreement (this
"AGREEMENT") is dated as of June 4, 2002 and is by and among Electric City
Corp., a Delaware corporation (the "COMPANY"), Newcourt Capital USA Inc., a
Delaware corporation, EP Power Finance L.L.C., a Delaware limited liability
company, Morgan Stanley Dean Witter Equity Funding, Inc., a Delaware
corporation, Originators Investment Plan, L.P., a Delaware limited partnership,
Duke Capital Partners, LLC, a Delaware limited liability company, Leaf Mountain
Company, LLC, an Illinois limited liability company and Richard P. Kiphart, an
individual.

                              W I T N E S S E T H:

     WHEREAS, the parties hereto other than Richard P. Kiphart are parties to
that certain Stockholders Agreement dated as of July 31, 2001 (as in effect on
the date hereof, the "EXISTING AGREEMENT"); and

     WHEREAS, Richard P. Kiphart and the Company are parties to that certain
Securities Purchase Agreement, dated as of May 31, 2002 (as it may be amended
from time to time, the "SERIES C SECURITIES PURCHASE AGREEMENT"), whereby the
Company has agreed to sell and Mr. Kiphart has agreed to purchase shares of the
Company's Series C Preferred Stock (as herein defined) together with shares of
the Company's Common Stock (as defined in the Existing Agreement) and warrants
to purchase additional shares of Series C Preferred Stock and warrants to
purchase additional shares of Common Stock; and

     WHEREAS, it is a condition precedent to the obligation of Richard P.
Kiphart to purchase such shares of Series C Preferred Stock and Common Stock and
such warrants that the parties hereto enter into this Agreement and the Company
and the other parties hereto are agreeable to the same;

     NOW, THEREFORE, the Parties agree as follows:

     1.   DEFINITIONS. All terms capitalized but not defined herein shall have
the meaning attributable to such terms in the Existing Agreement, except where
the context otherwise requires.

     2.   AMENDMENT OF EXISTING AGREEMENT. The Existing Agreement is hereby
amended as follows:

     A.   The following new defined terms are added to the definitions in
Section 1.1:

          "SERIES C CERTIFICATE OF DESIGNATIONS" means the Certificate of
     Designations, Preferences and Relative, Participating, Optional and Other
     Special Rights of Preferred Stock and Qualifications, Limitations and
     Restrictions Thereof of Series C Convertible Preferred Stock of the
     Company, as filed with the Secretary of State of Delaware.

          "SERIES C INVESTOR" means Richard P. Kiphart.

          "SERIES C PREFERRED STOCK" means shares of the Company's Series C
     Convertible

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     Preferred Stock, par value $0.01 per share, issued pursuant to the Series C
     Securities Purchase Agreement, or issued pursuant to the Series C Preferred
     Stock Warrants, or issued as dividends upon shares of the Series C
     Preferred Stock issued pursuant to the Series C Securities Purchase
     Agreement or the Series C Preferred Stock Warrants.

          "SERIES C SECURITIES PURCHASE AGREEMENT" means that certain Securities
     Purchase Agreement dated as of May 31, 2002 between the Series C Investor
     and the Company, as it may be amended from time to time with the consent of
     the other parties hereto.

          "SERIES C PREFERRED STOCK WARRANTS" means the warrants issued to
     certain of the Holders to purchase 50,000 shares of Series C Preferred
     Stock as evidenced by that certain warrant certificate, of even date
     herewith, issued by the Company to the Series C Investor, as it may be
     amended from time to time, with the consent of the Series A Investors.

     B.   The definition of Additional Purchaser is amended and restated in its
entirety as follows:

          "ADDITIONAL PURCHASER" means each purchaser under the Additional
     Purchase Agreement or the Series C Securities Purchase Agreement.

     C.   Section 2.5 is amended and restated in its entirety as follows:

          "2.5  APPROVAL OF CERTAIN ACTIONS BY HOLDERS OF SERIES A PREFERRED
     STOCK.

          (a)   For so long as any shares of Series A Preferred Stock or Series
     C Preferred Stock remain issued and outstanding, the Company shall not
     without the affirmative written consent or approval of the holders of
     record representing 75% or more of the aggregate number of shares of Series
     A Preferred Stock and Series C Preferred Stock then outstanding, voting as
     a single class to the exclusion of all other classes of the Company's
     capital stock (such consent or approval to be given by written consent in
     lieu of a meeting if allowable under the Company's Certificate of
     Incorporation or by vote at a meeting called for such purpose for which
     notice shall have been given to the holders of the Series A Preferred Stock
     and the holders of the Series C Preferred Stock):

                (i)    enter into any agreement that would restrict the
          Company's ability to perform under the Securities Purchase Agreement,
          the Additional Purchase Agreement or the Series C Securities Purchase
          Agreement;

                (ii)   amend its Certificate of Incorporation (including the
          Certificate of Designations and/or the Series C Certificate of
          Designations) or Bylaws in any way that could adversely affect, alter
          or change the rights, powers or preferences of the Series A Preferred
          Stock or the Series C Preferred Stock;

                (iii)  engage in any transaction that would impair or reduce the
          rights, powers or preferences of the Series A Preferred Stock, as a
          class or the Series C Preferred Stock as a class;

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                (iv)   complete any Change of Control Transaction (PROVIDED that
          if less than 400,000 shares in the aggregate of the Series A Preferred
          Stock and the Series C Preferred Stock are then outstanding (as
          adjusted for stock splits, stock combinations, recapitalizations and
          the like) and the then holders of Series A Preferred Stock and/or
          Series C Preferred Stock refused to consent to such Change of Control
          Transaction pursuant to this SECTION 2.5(a)(iv), the Company may, at
          its option, redeem all, but not less than all, of such outstanding
          shares of Series A Preferred Stock pursuant to Section 6(e)(i)(D) of
          the Certificate of Designations and/or redeem all, but not less than
          all, of such outstanding shares of Series C Preferred Stock pursuant
          to Section 6(b)(i)(4) of the Series C Certificate of Designations.

          (b)   For so long as at least 800,000 shares in the aggregate of
     Series A Preferred Stock and Series C Preferred Stock remain issued and
     outstanding (as adjusted for stock splits, stock combinations,
     recapitalizations and the like), the Company shall not, without the
     affirmative written consent or approval of the holders of record of shares
     representing 66-2/3% of the aggregate number of shares of Series A
     Preferred Stock and Series C Preferred Stock then outstanding, voting as a
     single class to the exclusion of all other classes of the Company's capital
     stock (such consent or approval to be given by written consent in lieu of a
     meeting if allowable under the Company's Certificate of Incorporation or by
     vote at a meeting called for such purpose for which notice shall have been
     given to the holders of the Series A Preferred Stock and to the holders of
     the Series C Preferred Stock):

                (i)    authorize or issue any capital stock or other equity
          security with rights, preferences or privileges that are senior to or
          pari passu with the Series A Preferred Stock or the Series C Preferred
          Stock, or any securities convertible or exchangeable into such capital
          stock or equity, other than:

                       (A) Series A Preferred Stock issued upon exercise of the
                Series A Preferred Stock Warrants issued pursuant to the
                Securities Purchase Agreement or the Additional Purchase
                Agreement;

                       (B) Series A Preferred Stock issued as payment in kind of
                any accrued but unpaid dividends on the Series A Preferred
                Stock;

                       (C) Series C Preferred Stock issued upon exercise of the
                Series C Preferred Stock Warrants issued pursuant to the Series
                C Securities Purchase Agreement; or

                       (D) Series C Preferred Stock issued as payment in kind of
                any accrued but unpaid dividends on the Series C Preferred
                Stock;

                (ii)   authorize or issue any options, rights or warrants to
          purchase capital stock of the Company or enter into any agreement or
          amendment with respect to any outstanding options, rights or warrants
          to purchase capital stock of the Company that reduces or that has the
          effect of reducing the per share exercise

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          price for any such options, rights or warrants or by canceling
          existing options, rights or warrants in connection with the grant of a
          new option, right or warrant;

                (iii)  authorize or issue any debt securities of the Company or
          any of its subsidiaries, other than debt under the Company's existing
          revolving lines of credit in effect on July 31, 2001 or the
          replacement thereof on substantially similar terms, and any additional
          debt up to $1,000,000 in the aggregate issued or incurred in the
          ordinary course of business (excluding trade payables incurred in the
          ordinary course of business);

                (iv)   purchase, redeem, or otherwise acquire any of the
          Company's capital stock, other than (x) the redemption of the Series A
          Preferred Stock, or (y) the redemption of the Series C Preferred
          Stock;

                (v)    enter into an acquisition, sale, merger, joint venture,
          consolidation or reorganization involving the Company or any of its
          subsidiaries;

                (vi)   sell or lease assets of the Company or any of its
          subsidiaries, except in the ordinary course of business;

                (vii)  declare or pay any cash dividends or make any
          distributions on any of its capital stock, other than on the Series A
          Preferred Stock and the Series C Preferred Stock;

                (viii) authorize the payment or pay to any individual employee
          of the Company of cash compensation in excess of $500,000 per annum;
          or

                (ix)   enter into any transaction (or series of transactions),
          including loans, with any employee, officer or director of the Company
          or to or with his, her or its affiliates or family members (other than
          with respect to payment of compensation to actual full-time employees
          in the ordinary course of business) involving $50,000 or more per year
          individually or $250,000 or more per year in the aggregate.

                (c)    For so long as at least 1,200,000 shares in the aggregate
          of Series A Preferred Stock and Series C Preferred Stock remain issued
          and outstanding (as adjusted for stock splits, stock combinations,
          recapitalizations and the like), the Company shall not, without the
          affirmative written consent or approval of the holders representing
          66-2/3% of the aggregate number of shares of Series A Preferred Stock
          and Series C Preferred Stock then outstanding, voting as a single
          class to the exclusion of all other classes of the Company's capital
          stock (such consent or approval to be given by written consent in lieu
          of a meeting if allowable under the Company's Certificate of
          Incorporation or by vote at a meeting called for such purpose for
          which notice shall have been given to the holders of the Series A
          Preferred Stock and the holders of the Series C Preferred Stock):

          (i)   terminate or newly appoint the chief executive officer or
     president of the

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     Company;

          (ii)  approve any annual capital expense budget if such budget
     provides for annual capital expenditures by the Company and its
     subsidiaries in excess of $1,000,000 in the aggregate in any year; or

          (iii) approve the incurrence of any single capital expenditure (or
     series of related capital expenditures) in excess of $500,000; PROVIDED,
     HOWEVER, the Company may make any reasonable emergency capital expenditure
     that the Board of Directors determines is necessary to maintain the
     operations of the Company as a result of a catastrophic event.

     D.   Section 2.6 is amended and restated in its entirety as follows:

          2.6   SUCCESSORS. The provisions of this Agreement shall be binding
     upon the successor in interest to any Holder of the Series A Preferred
     Stock and upon the successors in interest to any Holder of the Series C
     Preferred Stock. The Company shall not permit the transfer of any of the
     Series A Preferred Stock or any of the Series C Preferred Stock on its
     books or issue a new certificate representing any of the Series A Preferred
     Stock or the Series C Preferred Stock unless and until the Person to whom
     such Series A Preferred Stock or Series C Preferred Stock is to be
     transferred shall have executed a written agreement, substantially in form
     the form of this Agreement, pursuant to which such Person becomes a party
     to this Agreement and agrees to be bound by all the provisions hereof as if
     such Person were a Holder hereunder; provided, however, that such successor
     Persons shall not have any rights to designate any Directors pursuant to
     SECTION 2.1(a) nor any rights under SECTION 2.3 (except in the case of
     SECTION 2.1(a) or SECTION 2.3 if such Person is an Affiliate of a Holder
     having rights thereunder).

     E.   Section 2.7 is amended and restated in its entirety as follows:

          2.7   AGGREGATION. For purposes of determining the number of shares of
     Series A Preferred Stock or Series C Preferred Stock held (or converted) by
     a Holder pursuant to this Article II, the number of shares of Series A
     Preferred Stock or Series C Preferred Stock held (or converted) by all of
     such Holder's Affiliates shall be aggregated with the number of shares of
     Series A Preferred Stock and Series C Preferred Stock held (or converted)
     by such Holder.

     F.   Section 2.8 is amended and restated in its entirety as follows:

     2.8  AGREEMENT OF ADDITIONAL PURCHASERS REGARDING SPECIAL APPROVAL RIGHTS
VOTE. In connection with any vote, approval or written consent of the holders of
shares of Series A Preferred Stock and/or Series C Preferred Stock pursuant to
Section 2.5 of this Agreement (and/or Section 6(e) of the Certificate of
Designations and/or Section 6(b) of the Series C Certificate of Designations),
each Additional Purchaser (and its Affiliates or their respective transferees)
shall vote or otherwise grant its approval or written consent for its shares of
Series A Preferred Stock or Series C Preferred Stock, as applicable (prior to
the close of voting but after the votes, approvals or written consents of all of
the other holders of Series A Preferred Stock

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casting votes, approvals or written consents have been tallied) in the same
proportion to the aggregate affirmative and negative votes, approvals or written
consents of the other holders of Series A Preferred Stock, with respect to each
proposal submitted for vote, approval or written consent.

     G.   Clause (a) of Section 3.1 (other than the legend stated therein which
shall remain unchanged) is amended and restated in its entirety as follows:

          (a)   All certificates for shares of Series A Preferred Stock and/or
     shares of Series C Preferred Stock that are subject to the terms and
     provisions of Article II hereof, in addition to such other legend as may be
     required by law, shall, in the case of Series A Preferred Stock, bear the
     legend set forth in Section 9.3 of the Securities Purchase Agreement (and
     any other legend required by any other agreement contemplated by the
     Securities Purchase Agreement), and in the case of Series C Preferred
     Stock, bear the legend set forth in Section 8.3 of the Series C Securities
     Purchase Agreement (and any other legend required by any other agreement
     contemplated by the Series C Securities Purchase Agreement), as applicable,
     and the following legend:

     H.   Clause (ii) of Section 3.9 is amended and restated in its entirety as
follows:

          (ii)  If to a Holder: at the address set forth in the Securities
     Purchase Agreement, the Additional Purchase Agreement or the Series C
     Securities Purchase Agreement, as applicable.

     I.   Schedule I is amended and restated in its entirety as follows:

                              SCHEDULE I - HOLDERS

     Newcourt Capital USA Inc. is a Holder.

     EP Power Finance, L.L.C. is a Holder.

     Morgan Stanley Dean Witter Equity Funding, Inc. together with Originators
     Investment Plan, L.P. are collectively a Holder.

     Duke Capital Partners, LLC is a Holder.

     Leaf Mountain Company, LLC is a Holder.

     Richard P. Kiphart is a Holder.

     3.   JOINDER. Each of the parties to this Agreement hereby agrees that
from and after date hereof Richard P. Kiphart shall be a party to and be bound
by the Stockholders Agreement, as amended by this Agreement, as a Holder
thereunder (as such term is defined therein).

     4.   REPRESENTATIONS. Each party to this Agreement hereby represents and
warrants to each of the other parties to this Agreement that this Agreement has
been duly executed and delivered by such party and constitutes the valid and
binding obligation of such party, enforceable against such party in accordance
with its terms, subject to bankruptcy, insolvency, fraudulent transfer,
reorganization, moratorium and similar laws of general applicability relating

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to or affecting creditors' rights and to general equity principles. Richard P.
Kiphart hereby acknowledges that he has received a copy of the Stockholders
Agreement.

     5.   MISCELLANEOUS.

     (a)  All terms, covenants, agreements, representations, warranties and
undertakings in this Agreement shall bind and inure to the benefit of the
respective successors and assigns of the parties hereto whether so expressed or
not.

     (b)  Changes in or additions to this Agreement may be made or compliance
with any term, covenant, agreement, condition or provision set forth herein may
be omitted or waived, only in accordance with the provisions of the Stockholders
Agreement, as amended hereby.

     (c)  Except as to matters governed by the General Corporation Law of the
State of Delaware and decisions thereunder of the Delaware courts applicable to
Delaware corporations, which shall be governed by such laws and decisions,
this Agreement shall be construed and enforced in accordance with, and the
rights of the parties shall be governed by, the laws of the State of New York.

     (d)  This Agreement may be executed in counterparts, each of which shall
together constitute one and the same instrument.

     (e)  The section and paragraph headings herein are for convenience only and
shall not effect the construction hereof.

     (f)  The invalidity or unenforceability of any provision hereof shall in no
way affect the validity or enforceability of any other provision.

[Balance of page intentionally left blank; signature page follows.]

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     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their respective officers thereunto duly authorized as of the day
and year first above written.

COMPANY                                    HOLDERS

ELECTRIC CITY CORP.,                       NEWCOURT CAPITAL USA INC.,
a Delaware corporation                     a Delaware corporation

By:  /s/ John Mitola                       By:  /s/ Guy A. Piazza
   ---------------------------------         --------------------------------
Name:  John Mitola                         Name:    Guy A. Piazza
Title: Chief Executive Officer                 ------------------------------
                                           Title:   Senior Vice President
                                                 -----------------------------

                                           EP POWER FINANCE, L.L.C.,
                                           a Delaware limited liability company

                                           By:  /s/ Gar Seifullin
                                               -------------------------------
                                           Name:    Gar Seifullin
                                                ------------------------------
                                           Title:   Managing Director
                                                 -----------------------------

                                           MORGAN STANLEY DEAN WITTER
                                           EQUITY FUNDING, INC., a Delaware
                                           corporation

                                           By:  /s/ James M. Wilmott
                                               -------------------------------
                                           Name:    James M. Wilmott
                                                ------------------------------
                                           Title:   Vice President
                                                 -----------------------------

                                           ORIGINATORS INVESTMENT PLAN,
                                           L.P., a Delaware limited partnership

                                           By: MSDW OIP Investors, Inc., its
                                               general partner

                                           By:  /s/ James M. Wilmott
                                               -------------------------------
                                           Name:    James M. Wilmott
                                                ------------------------------
                                           Title:   Vice President
                                                 -----------------------------

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                                           DUKE CAPITAL PARTNERS, LLC,
                                           a Delaware limited liability company

                                           By:  /s/ Gerald J. Stalun
                                               -------------------------------
                                           Name:    Gerald J. Stalun
                                                ------------------------------
                                           Title:   EVP & Managing Director
                                                 -----------------------------

                                           LEAF MOUNTAIN COMPANY, LLC,
                                           an Illinois limited liability company

                                           By:  /s/ John J. Jiganti
                                               -------------------------------
                                           Name:    John J. Jiganti
                                                ------------------------------
                                           Title:   Manager
                                                 -----------------------------

                                           /s/ Richard P. Kiphart
                                           -----------------------------------
                                           Richard P. Kiphart

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                                                                  Exhibit 4.22

            JOINDER AND FIRST AMENDMENT TO INVESTOR RIGHTS AGREEMENT

     This Joinder and First Amendment to Investor Rights Agreement (this
"AGREEMENT") is dated as of June 4, 2002 and is by and among Electric City
Corp., a Delaware corporation (the "COMPANY"), Newcourt Capital USA Inc., a
Delaware corporation, Newcourt Capital Securities, Inc., a Delaware corporation,
EP Power Finance L.L.C., a Delaware limited liability company, Morgan Stanley
Dean Witter Equity Funding, Inc., a Delaware corporation, Originators Investment
Plan, L.P., a Delaware limited partnership, Duke Capital Partners, LLC, a
Delaware limited liability company, Leaf Mountain Company, LLC, an Illinois
limited liability company and Richard P. Kiphart, an individual.

                              W I T N E S S E T H:

     WHEREAS, the parties hereto other than Richard P. Kiphart are parties to
that certain Investor Rights Agreement dated as of July 31, 2001 (as in effect
on the date hereof, the "EXISTING AGREEMENT"); and

     WHEREAS, Richard P. Kiphart and the Company are parties to that certain
Securities Purchase Agreement, dated as of May 31, 2002 (as it may be amended
from time to time, the "SERIES C SECURITIES PURCHASE AGREEMENT"), whereby the
Company has agreed to sell and Mr. Kiphart has agreed to purchase shares of the
Company's Series C Preferred Stock (as herein defined) together with shares of
the Company's Common Stock (as defined in the Existing Agreement) and warrants
to purchase additional shares of Series C Preferred Stock and warrants to
purchase additional shares of Common Stock; and

     WHEREAS, it is a condition precedent to the obligation of Richard P.
Kiphart to purchase such shares of Series C Preferred Stock and Common Stock and
such warrants that the parties hereto enter into this Agreement and the Company
and the other parties hereto are agreeable to the same;

     NOW, THEREFORE, the Parties agree as follows:

     1.   DEFINITIONS. All terms capitalized but not defined herein shall have
the meaning attributable to such terms in the Existing Agreement, except where
the context otherwise requires.

     2.   AMENDMENT OF EXISTING AGREEMENT. The Existing Agreement is hereby
amended as follows:

     A.   The following new defined terms are added to the definitions in
Section 1.1:

          "SERIES A INVESTORS" means, collectively, Newcourt Capital USA Inc., a
     Delaware corporation, EP Power Finance L.L.C., a Delaware limited liability
     company, Morgan Stanley Dean Witter Equity Funding, Inc., a Delaware
     corporation, Originators Investment Plan, L.P., a Delaware limited
     partnership, Duke Capital Partners, LLC, a Delaware limited liability
     company, and Leaf Mountain Company, LLC, an Illinois limited liability
     company. "SERIES A INVESTOR" means any of such entities.

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          "SERIES C INVESTOR" means Richard P. Kiphart.

          "SERIES C PREFERRED STOCK" means shares of the Company's Series C
     Convertible Preferred Stock, par value $0.01 per share, issued pursuant to
     the Series C Securities Purchase Agreement, or issued pursuant to the
     Series C Preferred Stock Warrants, or issued as dividends upon shares of
     the Series C Preferred Stock issued pursuant to the Series C Securities
     Purchase Agreement or the Series C Preferred Stock Warrants.

          "SERIES C PREFERRED STOCK WARRANTS" means the warrants issued to
     certain of the Investors to purchase 50,000 shares of Series C Preferred
     Stock as evidenced by that certain warrant certificate, of even date
     herewith, issued by the Company to the Series C Investor, as it may be
     amended from time to time, with the consent of the Series A Investors.

          "SERIES C SECURITIES PURCHASE AGREEMENT" means that certain Securities
     Purchase Agreement dated as of May 31, 2002 between the Series C Investor
     and the Company, as it may be amended from time to time with the consent of
     the Series A Investors.

     B.   The definition of Common Stock Warrants is amended and restated in its
entirety as follows:

          "COMMON STOCK WARRANTS" means (a) the warrants issued to the Series A
     Investors pursuant to the Securities Purchase Agreement and the Additional
     Purchase Agreement, as each may be amended from time to time, and (b) the
     warrants to purchase up to 281,250 shares of Common Stock issued to the
     Series C Investor pursuant to the Series C Securities Purchase Agreement,
     as amended from time to time.

     C.   The definition of Eligible Securities is amended and restated in its
entirety as follows:

          "ELIGIBLE SECURITIES" means (i) the shares of Common Stock issued or
     issuable upon the conversion of the Series A Preferred Stock issued or
     issuable pursuant to the Securities Purchase Agreement or the Additional
     Purchase Agreement or issued or issuable upon exercise of the Series A
     Preferred Stock Warrants and conversion of the Series A Preferred Stock
     issued or issuable pursuant to such exercise; (ii) the shares of Common
     Stock issued or issuable upon the conversion of the Series C Preferred
     Stock issued or issuable pursuant to the Series C Securities Purchase
     Agreement or issued or issuable upon exercise of the Series C Preferred
     Stock Warrants and conversion of the Series C Preferred Stock issued or
     issuable pursuant to such exercise; (iii) the shares of Common Stock issued
     pursuant to Securities Purchase Agreement; (iv) the shares of Common Stock
     issued pursuant to the Series C Securities Purchase Agreement; (v) the
     shares of Common Stock issued or issuable upon exercise of the Common Stock
     Warrants or upon exercise of the Placement Agent Warrants; and (vi) any
     other shares of Common Stock issued as (or issuable upon the conversion or
     exercise of any warrant, right or other security that is issued as) a
     dividend or other distribution with respect to or in exchange for or in
     replacement of, the shares described in clauses (i), (ii), (iii), (iv), (v)
     and this clause (vi); PROVIDED, HOWEVER, that the foregoing definition
     shall exclude in all

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     cases any Eligible Securities sold by a Holder in a transaction in which
     its rights under this Agreement are not also assigned; and PROVIDED FURTHER
     that any Eligible Securities sold pursuant to Rule 144 or sold in a
     registered public offering that has been declared effective shall no longer
     be Eligible Securities hereunder.

     D.   The definition of Investors is amended and restated in its entirety as
follows:

          "INVESTORS" means the Series A Investors, the Placement Agent and the
     Series C Investor, collectively, and "INVESTOR" means any of them.

     E.   The definition of Parties is amended and restated in its entirety as
follows:

          "PARTIES" means the Series A Investors, the Placement Agent, the
     Series C Investor and the Company, collectively, and "PARTY" means any of
     them.

     F.   Clause (d) of Section 3.1 is amended and restated in its entirety as
follows:

          (d)  The right of first offer in this Section 3.1 shall not be
     applicable (i) to the issuance or sale of Common Stock (or options
     therefore) to employees, consultants and directors pursuant to plans or
     agreements approved by the Board of Directors for the purpose of soliciting
     or retaining their services, (ii) to the issuance of securities in
     connection with a bona fide business acquisition of or by the Company,
     whether by merger, consolidation, sale of assets, sale or exchange of stock
     or otherwise, (iii) to Common Stock issued upon conversion of the Series A
     Preferred Stock or the Series C Preferred Stock or the exercise of the
     Common Stock Warrants or the Placement Agent Warrants, (iv) to the Series A
     Preferred Stock issued upon the exercise of Series A Preferred Stock
     Warrants or the Series C Preferred Stock issued upon the exercise of the
     Series C Preferred Stock Warrants, (v) to the issuance of securities
     pursuant to options, warrants, notes or other rights to acquire securities
     of the Company which were outstanding on July 31, 2001, (vi) to a Qualified
     Primary Offering, (vii) to the issuance of Series A Preferred Stock and
     Series A Preferred Stock Warrants pursuant to the Additional Purchase
     Agreement in compliance with Section 2.3 of the Securities Purchase
     Agreement, or (viii) to stock splits, stock dividends or like transactions.

     G.   Clause (ii) of Section 4.2 is amended and restated in its entirety as
follows:

          (ii) If to an Investor: at the address set forth in the Securities
     Purchase Agreement, the Additional Purchase Agreement or the Series C
     Securities Purchase Agreement, as applicable.

     H.   Schedule I is amended and restated in its entirety as follows:

                             SCHEDULE I - INVESTORS

     Newcourt Capital USA Inc.
     Newcourt Capital Securities, Inc.
     EP Power Finance, L.L.C.
     Morgan Stanley Dean Witter Equity Funding, Inc.

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     Originators Investment Plan, L.P.
     Duke Capital Partners, LLC
     Leaf Mountain Company, LLC
     Richard P. Kiphart

     3.   JOINDER. Each of the parties to this Agreement hereby agrees that
from and after date hereof Richard P. Kiphart shall be a party to and be bound
by the Investor Rights Agreement, as amended by this Agreement, as an Investor
and a Holder thereunder (as such terms are defined therein).

     4.   REPRESENTATIONS. Each party to this Agreement hereby represents and
warrants to each of the other parties to this Agreement that this Agreement has
been duly executed and delivered by such party and constitutes the valid and
binding obligation of such party, enforceable against such party in accordance
with its terms, subject to bankruptcy, insolvency, fraudulent transfer,
reorganization, moratorium and similar laws of general applicability relating to
or affecting creditors' rights and to general equity principles. Richard P.
Kiphart hereby acknowledges that he has received a copy of the Investor Rights
Agreement.

     5.   MISCELLANEOUS.

     (a)  All terms, covenants, agreements, representations, warranties and
undertakings in this Agreement shall bind and inure to the benefit of the
respective successors and assigns of the parties hereto whether so expressed or
not.

     (b)  Changes in or additions to this Agreement may be made or compliance
with any term, covenant, agreement, condition or provision set forth herein may
be omitted or waived, only in accordance with the provisions of the Investor
Rights Agreement, as amended hereby.

     (c)  This Agreement shall be governed and construed in accordance with the
laws of the State of New York without giving effect to the conflict of laws
principles thereof.

     (d)  This Agreement may be executed in counterparts, each of which shall
together constitute one and the same instrument.

     (e)  The section and paragraph headings herein are for convenience only and
shall not effect the construction hereof.

     (f)  The invalidity or unenforceability of any provision hereof shall in no
way affect the validity or enforceability of any other provision.

[Balance of page intentionally left blank; signature page follows.]

                                      - 4 -
<Page>

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their respective officers thereunto duly authorized as of the day
and year first above written.

COMPANY                                    HOLDERS

ELECTRIC CITY CORP.,                       NEWCOURT CAPITAL USA INC.,
a Delaware corporation                     a Delaware corporation

By: /s/ John Mitola                        By:  /s/ Guy A. Piazza
   --------------------------------           --------------------------------
Name:  John Mitola                         Name:    Guy A. Piazza
Title: Chief Executive Officer                  ------------------------------
                                           Title:   Senior Vice President
                                                 -----------------------------

                                           EP POWER FINANCE, L.L.C.,
                                           a Delaware limited liability company

                                           By:  /s/ Gar Seifullin
                                              --------------------------------
                                           Name:    Gar Seifullin
                                                ------------------------------
                                           Title:   Managing Director
                                                 -----------------------------

                                           MORGAN STANLEY DEAN WITTER
                                           EQUITY FUNDING, INC., a Delaware
                                           corporation

                                           By:  /s/ James M. Wilmott
                                              --------------------------------
                                           Name:    James M. Wilmott
                                                ------------------------------
                                           Title:   Vice President
                                                 -----------------------------

                                           ORIGINATORS INVESTMENT PLAN,
                                           L.P., a Delaware limited partnership

                                           By:  MSDW OIP Investors, Inc., its
                                                general partner

                                           By:  /s/ James M. Wilmott
                                              --------------------------------
                                           Name:    James M. Wilmott
                                                ------------------------------
                                           Title:   Vice President
                                                 -----------------------------

                                      - 5 -
<Page>

                                           DUKE CAPITAL PARTNERS, LLC,
                                           a Delaware limited liability company

                                           By:  /s/ Gerald J. Stalun
                                              --------------------------------
                                           Name:    Gerald J. Stalun
                                                ------------------------------
                                           Title:   EVP & Managing Director
                                                 -----------------------------

                                           NEWCOURT CAPITAL SECURITIES,
                                           INC., a Delaware corporation

                                           By:  /s/ Guy A. Piazza
                                              --------------------------------
                                           Name:    Guy A. Piazza
                                                ------------------------------
                                           Title:   Managing Director
                                                 -----------------------------

                                           LEAF MOUNTAIN COMPANY, LLC,
                                           an Illinois limited liability company

                                           By:  /s/ John J. Jiganti
                                              --------------------------------
                                           Name:    John J. Jiganti
                                                ------------------------------
                                           Title:   Manager
                                                 -----------------------------

                                           /s/ Richard P. Kiphart
                                           -----------------------------------
                                           Richard P. Kiphart

                                      - 6 -

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