Superman's power coming from sunlight makes little sense

If Superman absorbed visible light from the sun then wouldn't he be
black?  Seriously.  That's what happens when you absorb visible light.

I suppose the argument could be made that sunlight has a catalytic
effect and that Superman's real source of power is actually something
else.

If anybody really cares, that is.  I'm just pointing out that a solar
powered Superman doesn't make a lot of sense.

Martin