Dozens of employees and customers were evacuated from the Safeway store on Mangrove Avenue in Chico Wednesday afternoon.
Firefighters responded to smoke on the roof of the store around 2:40 p.m. The fire never got into the building.
Fire investigators say there was metal flooring on the roof that kept the fire from doing any damage to the inside of the store.
Firefighters say it was caused by a fire in an electrical box involving the solar panels.