Solar panels, how high should they be above the roof

Seems like if they didn't want you drillin new holes, they would put the ones they drilled in the right places. I have never used an existing mounting hole, and I sure don't worry about panel warranty either. Has there ever been a panel go bad on this forum ?? I never read any. And what would it cost to ship one back,...at least .50 a watt ??

Nutserts do not hold up in thin metal,...don't waste your money

One panel I bought was a 1/4" thick for 6" long on all 4 corners,...no reinforcing needed.