Even if it was just 0 albedo no generation, irradiation on whatever's parked beneath would be cut in half plus rest of (re-)radiation converted into far-ir. This is not unuseful. Just don't mandate this kind of thing in places where parking lots have to be cleaned up with bulldozers in winter.
If there are solar panels over the parking lot, then the parking lot doesn't have to be plowed. You can design the panels at appropriate slopes to direct the snow off the lot.
You're not looking at the albedo of the solar panels in isolation though, you're comparing it to asphalt and cars. Typical solar panels have an albedo of ~0.3. Asphalt around ~0.05.
