Of course your right about that, but not all white paints are really bright and I have no information to make me assume they all reflect UV the same. My humble opinion if using white paint, then flat white titanium would probably come closest in efficiency. Even the whitest paint has some absorbtion.
Originally Posted by efikim
If I were going for maximum output a highly mirrored surface would be a better bet.
If I were going for ease of construction and cost factor the paint would win hands down.