I probably ought to disclose that I have a significant area of roof for roof heating that is not used as habitable space. This is always an advantage for collecting the rays. I built a large 'L' shaped porch addition to my house in 2011. Here's some pics:
The first is the East side and the second is the South side. I'm thinking of adding some solar PV on the South side at a later date. That will cut into the heating effect somewhat. I have a plan though. I have an attached garage that is disconnected from the rest of the house from the ceiling to the roof. If I go ahead with the solar PV I will build a thermal channel from the garage roof to the house roof above the ceilings. Here's the plan. The top is North. Everything within the dotted line is habitable space and will remain so.
It would give me a little over 3000 watts, which would I think would be plenty since I don't need it for heating. No car charging though.