Solar panels, how high should they be above the roof

Thanks.
I'm bolting some angle to the frame of the panel using the factory mounting location (I've heard drilling the frame will void the warranty?) and another piece of angle to the roof with a bolt between the two.

No shortage of rain up here normally, dry as a popcorn fart this summer though, stage 3 water restrictions, no lawn watering at all, can't even wash vehicles (or rv's).