He can because he stores energy in his cells. It's true, if he couldn't store the energy of Sun in his cells he would kind of "lose" his strength and be an ordinary man. But actually it could never really happen, though, as we all know. :) As I remember without his cell attributes he wouldn't really have any special powers or so, mainly it all makes all his superpowers possible.
superman
Superman died in the fight with Domesday in the Death of Superman storyline in 1992.
usually superman.
Superman is dead.Hancock by default.
superman obv. i saw them fight.
superman.
Superman
superman
Superman
superman
Still Superman, Superman is too smart for that.
Superman easily.