One problem: all this energy is eventually turned into heat ...
Not sure about the exact numbers, but I guess that at the moment normal roofs and solar panels absorb very roughly about the same percentage of sunlight.
So if in the future solar panels become more efficient, then yes, the amount of sunlight turned into heat could double.
Maybe that can be offset by covering other parts of earth with reflective materials or finding a way to send the heat back into the universe more effectively.
And also, people should paint their roofs white.
Some could, but a dark roof can be beneficial in the winter