Approximately 1000 sq metres of roof was damaged in a solar farm blaze at the business park in Albourne Road, Henfield on Friday (April 18).
Fifty square metres of roof mounted solar panels burst into flames at a two storey building used for warehousing and offices.
Power was isolated to the panels by West Sussex Fire and Rescue and the building was inspected internally for signs of fire, but none were found.
The fire was allowed to burn out under control of fire crews using an aerial ladder platform, a ladder and thermal imaging camera.
Fire crews from Partridge Green, Burgess Hill, Horsham and Crawley were called just after 10.30am and remained at the scene of the fire for more than three hours.
The blaze was ruled accidental.