In a statement,the California-based company says fixing the problem will add $16m to $20m tothe cost of solar system sales for the first three quarters of 2013, and $20mto $23m for 2012.

Chiefexecutive Lyndon Rive told analysts on a conference call that the problem wasdiscovered during an internal audit of fourth quarter financial statements.

He saidthe company had assigned an excessive amount of overhead expenses to its solarleases while shortchanging solar array sales.