Parking lots are dangerous to build over, for two reasons:

1) people cannot drive. The amount of dents or other damage from incompetent drivers done to a concrete-built park house is crazy, I don't want to imagine the damage they'll do to tiny aluminium/steel constructions holding the panels

2) people cannot drive. They underestimate their vehicle height all the time - just google for "can opener bridge". Just a couple days ago a truck driver massively damaged the lighting in a Munich tunnel because he forgot that the excavator on the flatbed was higher than the truck...

There is no reason to make them tiny: http://solairegeneration.com/project/rutgers-university/

You just build the solar panel mounts like you would usually build lighting mounts (big concrete bases).

Height is less of a concern in some parking lots (where it's virtually all cars)

> They underestimate their vehicle height all the time

There's a simple way to fix that: Have a solid steel bar slightly lower than the max clearance at the entrance. People that can't drive will notice there without causing further damage.

Not to mention multi-level parking lots, which have height restrictions imposed by the structure itself. I'm sure most people wouldn't mind having the top level covered as well.