EXHIBIT 10.1


                                 PROMISSORY NOTE


THIS  PROMISSORY  NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS  AMENDED (THE "ACT"), OR ANY APPLICABLE STATE SECURITIES LAWS, AND MAY NOT BE
SOLD  OR  TRANSFERRED  UNLESS  SUCH  SALE  OR TRANSFER IS IN ACCORDANCE WITH THE
REGISTRATION  REQUIREMENTS  OF  SUCH  ACT  AND  APPLICABLE  LAWS  OR  SOME OTHER
EXEMPTION  FROM THE REGISTRATION REQUIREMENTS OF SUCH ACT AND APPLICABLE LAWS IS
AVAILABLE  WITH  RESPECT THERETO.  THE MAKER OF THIS PROMISSORY NOTE MAY REQUIRE
AN OPINION OF COUNSEL IN FORM AND SUBSTANCE REASONABLY SATISFACTORY TO THE MAKER
TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS IN COMPLIANCE WITH THE ACT
AND  ANY APPLICABLE STATE SECURITIES LAWS.  ANY TRANSFER OF THIS PROMISSORY NOTE
NOT  MADE IN COMPLIANCE WITH THE FOREGOING WILL BE NULL AND VOID AND OF NO FORCE
OR  EFFECT.

                                 PROMISSORY NOTE

$6,000,000     Pennington, New Jersey

January 25, 2008

     FOR  VALUE  RECEIVED,  WorldWater  &  Solar  Technologies Corp., a Delaware
corporation  ("Maker"  or  "Company"),  together with any person or entity which
succeeds  to  or assumes the obligations under this Note, hereby promises to pay
to  the order of The Quercus Trust ("Payee"), the principal amount of $6,000,000
(the  "Principal  Amount") on the date that is 6 months after the date first set
forth  above  (the  "Due  Date") or as otherwise provided herein.  The Principal
Amount  outstanding  from time to time shall bear interest at a rate equal to 8%
per  annum.  Such  interest shall accrue and shall be due and payable in arrears
(together  with  the Principal Amount) on the Due Date.  All payments by Company
under  this  Note  shall  be  in  immediately  available  funds in U.S. Dollars.

     Upon  the  occurrence  of any one or more Events of Default (as hereinafter
defined), the Principal Amount balance and all unpaid accrued interest hereunder
shall  become  im-mediately due and payable without notice or demand, and, until
this  Note  is paid in full, this Note shall continue to bear interest at a rate
equal  to  8%  per  annum.

     The  following  shall  constitute  "Events  of  Default":
     (a)     The  failure by Maker to pay any amount or issue any securities due
hereunder;  or
     (b)     The  appointment  of a receiver, liquidator, assignee or like party
of  any property, the assignment or trust mortgage for the benefit of creditors,
the  commencement  of any kind of insolvency proceedings under any bankruptcy or
other law relating to the relief of debtors, or the entry of an order for relief
with  respect  to  the  Company  in any proceeding pursuant to the United States
Bankruptcy  Code,  as  amended.
     Payment  of  the  Principal  Amount  and  accrued  interest  hereunder (the
"Aggregate  Debt") shall be made in lawful money of the United States of America
at  the  address  of Payee set forth below, or at such other place as the holder
hereof  shall  have  designated to Maker in writing.  The Aggregate Debt, or any
portion  thereof,  may be prepaid in whole or in part, at any time and from time
to  time without penalty or premium.  In the event of prepayment of a portion of
the  Aggregate  Debt  prior  to the Due Date, Payee shall nonetheless retain the
conversion  rights  hereinafter  described  with  respect to that portion of the
Aggregate  Debt  that  remains  outstanding  on  the  Due  Date.
     Maker  hereby  waives presentment, demand for payment, notice, protest, and
all  other  demands  and  notices  in  connection with the delivery, acceptance,
performance,  default,  or  enforcement  of  this Note.  No course of dealing of
Payee  or  another  holder  hereof nor any failure or delay by Payee or any such
holder  to exercise any right, power, or privilege under this Note shall operate
as  a  waiver  hereunder or thereunder and any single or partial exercise of any
such right, power, or privilege shall not preclude any later exercise thereof or
any  exercise  of  any other right, power, or privilege hereunder or thereunder.
No  covenant,  obligation, or other provision of this Note may be waived, and no
consent  contemplated hereby may be given, other than in writing signed by Payee
or another holder waiving such covenant, obligation, or provision or giving such
consent.
     It  is contemplated that the parties will negotiate a purchase of equity of
payee  by  The  Quercus Trust and this Note will be utilized as a portion of the
consideration  for  such  transaction.  However, neither party shall be bound to
negotiate  or  consummate  any  such  transaction..
     To  the  extent  permitted  by  generally  accepted  accounting principles,
Company  will  treat,  account,  and report this Note as debt and not equity for
accounting  purposes  and with respect to any returns filed with federal, state,
or  local  tax  authorities.
     Company  and  Payee  shall pay all costs and expenses that each incurs with
respect  to  the  negotiation, execution, delivery, and performance of this Note
and  the  documents  related  hereto;  provided,  however,  that  Company  shall
reimburse  Payee  for  the  reasonable  fees, costs, and expenses of its counsel
incurred  to  enforce  or  collect  this  Note.  All  payments received by Payee
hereunder  will  be  applied  first  to  costs  of  collection,  if any, then to
interest,  and  the  balance  to  principal.
     The  provisions  of  this  Note  shall  be  governed  by, and construed and
enforced  in accordance with, the substantive laws of the State of placeStateNew
Jersey,  without  regard  to  its  principles  of  conflicts  of  laws.

                  [Signatures set forth on the following page]


<PAGE>




IN  WITNESS WHEREOF, the undersigned has executed this Note as of the date first
above  written.

                                   WorldWater & Solar Technologies Corp.


                                   By:   /s/ Quentin T. Kelly
                                        --------------------------------
                                             Quentin T. Kelly
                                   Title:    CEO


AGREED AND ACCEPTED


---------------------------------------
The Quercus Trust, David Gelbaum,
Co-Trustee of The Quercus Trust