Sentry isn't directly powered by the sun. Having drunk his wonderous serum, he has the power of A Million Exploding Suns. The serum gives him great strenght, speed, dominion over light, and puts his molecules in a phaseshift, putting him a second ahead of the rest of reality endowing him with a hyperstate of consciousness with which anything is possible. We've seen very little of him, but so far he's a pretty bad mama jama.
While the full extent of the Sentry's solar-based abilities is unknown, he has demonstrated super-strength, invulnerability, super-speed, the power of flight and the capacity to control light. The Sentry's abilities derive from an experimental serum that creates a phase-shift in his molecules, causing each atom to step an instant ahead of the current timeline. The serum induces a photosynthetic reaction, resulting in a hyperstate of consciousness. In effect, the Sentry's powers are limitless.
in other words superman goes down
I agree, but anyway, look at heroes like Thor, The Thing, or Wonder Man.
They are heavyweights, strenght, invulnerability(resistance in the Thing case), they are the slugfest heroes, but they are not unbeatable.Yes they are tough as hell but not unbeatable.It's what make me like them, they are someone that you don't want to meet if you're a supercriminal but if you're a sc with sufficient power you have a chance.