CUSIP No.      739308104

AGREEMENT TO FILE JOINT SCHEDULE 13D

     Each of the undersigned, being a record owner or “beneficial owner” of the common stock of Power One, Inc. (“Common Stock”), hereby agrees to jointly file a Schedule 13D with respect to their respective holdings of the Common Stock and to include this agreement as an exhibit to such Schedule 13D.

     IN WITNESS WHEREOF, each of the undersigned has executed and delivered this agreement as of the 17th day of March, 2008.

/s/ David A. Knight

David A. Knight, as attorney in fact for Jackson T. Stephens Trust
No. One, Warren A. Stephens, Warren & Harriet Stephens Children’s Trust, Harriet C. Stephens Trust, Harriet C. Stephens, Warren Miles Amerine Stephens Trust, John Calhoun Stephens Trust, Laura Whitaker Stephens Trust, Douglas H. Martin, and Curtis F. Bradbury, Jr.