For the heat island effect the distinction is immaterial. The city itself is still absorbing more heat, this heat must go somewhere.

Your reasoning is a bit like assuming solar panels stop flooding because they prevent the roof from getting wet.

My point was that a carbon black shingle would result in a much higher amount of work required to cool the inside of the house because you'd be baking yourself alive. The standoffs for solar prevent that. Which at 20% efficiency panels, back of the envelope says that could end up cancelling out the benefit of the panels entirely, for more than half the year.