[notahacker]

You can use everything as a radiator, but you can't use everything as a radiator sufficiently efficient to cool hot chips to safe operating temperature, particularly not if that thing is a thin panel intentionally oriented to capture the sun's rays to convert them to energy. Sure, you can absolutely build a radiator in the shade of the panels (it's the most logical place), but it's going to involve extra mass.

[dsr_]

You also want to orient those radiators at 90 degrees to the power panels, so that they don't send 50% of their radiation right back to the power panels.