Comment by db48x

If you gather 1kW of power from the sun then you have to reject 1kW of heat once you are done with whatever computation you are doing. There’s a bit more heat absorbed from the environment since some sunlight strikes parts of your satellite that are not solar panels, but it’s not too bad. Starlink satellites, just to pick a relevant example, do not need a radiator at all because they stay mostly edge–on to the sun and they can radiate all the heat through their own surface area. The ISS needs big radiators because they want it to be comfortable for humans, but electronics can run significantly hotter than that.