Abstract: A roof panel comprising a rigid sheet (1) of material for forming a structural roof. The sheet is formed with a plurality of ridges (2), and a flexible solar material (6) attached along at least one of the ridges. The maximum height of at least one ridge (2) above the lowermost plane of the sheet is greater than 50 cm. A method of forming the roof panel comprises forming through holes (11) in the metal sheet, adhering a flexible solar material (6) along at least one of the ridges, and miming electrical connections (7) to the solar panel through the holes to the underside of the ridges (2).