Top of my head thought:

Depends on the colour of the cars and pavement. A PV will send ~20% of the light energy hitting it down the wire, the rest = heat.

PVs don’t really reflect back much light for obvious reasons.

The increased surface area might help it radiate more heat at night on a clear day, unless the panels are flat and then it’s no change really.

Is that 20% of the solar energy, or 20% of the visible light, or some other spectrum fraction? It's easy to lose track of what part of the spectrum you're discussing.