personaly i always lift them off the roof to allow air under neath they can get warm . i use 3in angle .its not cheap . of course it helps if they are already in an aluminium frame some are a little harder as they dont have their own square frame .i hope yours as. if not do it first . older panels had bolt slides on the side of the panels .
some do mount them on sun seeker tilt and swivel frames but they can be a bit expensive.mine are always trying to seek out the sun .dont know what happened today. anybody got any rain power panels. tried the lunar panels but they kept me awake at night with the light.
psif you put the angle across the roof you wont get them blow off and branches cant get underneath. i do go some silly places.