Canada

I thought solar over surface parking could be good in certain conditions, and maybe it can, in small installations. But there has been research done on this subject and it's not entirely clear. Large photovoltaic farms often increases heat island effect.

Source: The Photovoltaic Heat Island Effect: Larger solar power plants increase local temperatures

There is a cooling effect provided by the panels, because of the shade, but it's not that much. Putting them inside giant parking lots and over roads could ends up making things warmer around those areas.

Anyway, the point is not that we will require more or cleaner energy for those cars, the point is that they still create pollution, space, and lethal issues.

Car dependency should be reduced. Some highways and elevated expressways should be changed into urban boulevards or even simply demolished. Power usage should be stabilized. Consumption should be reduced. Habits should be changed.

It's unreasonable to expect everybody on the planet and in cities to have a 2 tons giant cube of metal wasting energy to move itself and the little bag of meat inside everywhere they go. Alternatives to car dependency have to be provided.

I'm sorry but solar panels here and there are not gonna be enough with the current trajectory.