I raced out and took this photo. 75mm x 50 mm X 3mm aluminium angle. I have three brackets like this on each of the long sides of the panel. Glued (sikaflex polyurethane glue) and screwed into the roof with those stainless screws. Its been there for 5 years now. Many just glue them to the roof with no screws -just make sure if you do to clean and use all the primers that they recommend on glue spec sheet. Then test them by pulling with at least 50 kg of force. I can rock the whole motorhome by pushing the panels. Or you could use buy those plastic mounts at the bottom.