system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] If Superman gets his power from the Sun, is his power output limited by the amount of energy the Sun radiates over its lifetime?
gpt
There is reason to suspect that Superman isn't solar powered; the amount of solar energy falling on a Superman-sized surface simply isn't enough to perform some of Superman's feats. 

An alternative speculation is that Superman is solar-catalyzed (using sunlight to catalyze more energetic reactions, eg cold fusion, matter annihilation, or to tap some other dimension). There are also those who believe that Superman is a reality warper. For either of these hypotheses, Superman doesn't actually use the Sun's energy, thus his power isn't limited to that amount.