system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] I'm a new supervillain in Metropolis. I can't find any Kryptonite, but I read in the Daily Planet that Superman's powers come from the sun. Is there a reason this weakness isn't exploited by his enemies more often, or should I try to beat the Man of Steel by cutting off his power source?
gpt
People tried it, trust me. The issue is, that while he really does absorb power from the sun, he tends to retain that power well long enough for him to finish any business that bothers him. He won't be depowered just by locking him in a dark room. 

So taking advantage of this would require a convoluted series of contraptions to lure Superman in and HOLD Superman in for a prolonged amount of time, and few supervillains have access to this sort of resources.