Orion Energy Systems (OESX) 8-K Changes in Registrant's Certifying Accountant

Exhibit 16.1

August 22, 2011

U.S. Securities and Exchange Commission
Office of the Chief Accountant
100 F Street, NE
Washington, DC 20549

Re: Orion Energy Systems, Inc.
File No. 01-33887

Dear Sir or Madam:

We have read Item 4.01 of Form 8-K of Orion Energy Systems, Inc. dated August 22, 2011 and agree with the statements concerning our Firm contained therein.

Very truly yours,

/s/ GRANT THORNTON LLP