While the black surfaces of solar panels absorb most of the sunlight that reaches them, only a fraction (around 15%) of that incoming energy gets converted to electricity. The rest is returned to the environment as heat. The panels are usually much darker than the ground they cover, so a vast expanse of solar cells…Solar panels in Sahara could boost renewable energy but damage the global climate – here’s why — Watts Up With That?
In addition, both solar panels and wind turbines have the potential of bringing rain to the desert. This is a problem because forest has a lower albedo than desert does. It’s darker, so it absorbs more heat.
I guess the answer to global warming might be to turn the Amazon forest into desert.