Comment by walrus01

There's a few different companies selling roof intended mounting systems that use weight/ballast to hold down panels at about a 20 degree angle (facing south, in the northern hemisphere), which are basically big plastic trays with some clips to hold the panels and a place to put concrete blocks. Some care has to be taken to prevent gaps that let wind get underneath them for worst-case windstorm scenarios, but it's definitely a product that exists.