Yes, the roof could be an issue. I'm not aware of any resi or comm leak issues, and tile roofs are few and far between over here.
Spoke to a PM today as to an upcoming comm job (4.26MW) scheduling. The roof rip-off should start tommorrow, & be about 3-4 weeks depending on weather.
BTW, one ground mount job has 225 watt panels.
The 'shading' thought never crossed my mind! I'll have to get one of the PM's to get some temp readings, perhaps an additional 'sales tool'??
