thanks!

i think this depends in part on how high a temperature you can tolerate; at 20° the stefan–boltzmann emissivity is only 420 watts per square meter for an ideal black body, a third of the above-the-atmosphere solar irradiance. the blackbody equilibrium stefan-boltzmann temperature for 1300 watts per square meter is 116°, which is a bit toasty for efficient solar panels; even at half that (if you're emitting infrared from the back of the pv array as well as the front) you're at 54°. and if you want to move your power plant closer to the sun to harvest that sweet, sweet radiation, the temperature goes up further

so plausibly some heatpipes painted black sticking far out the backside would be helpful

Or, just go with PV that tolerates higher temperature better. GaAs PV cells are used in some satellites for this reason, I think. Here on Earth, CdTe is used in place of Si in some hotter environments for this reason as well. CdTe has the advantage of being extremely thin (the absorption length of photons in the material is something like 0.1 microns) which could be an advantage in space, where the PV arrays could be deployed as extremely thin sheets, much thinner than modules on the ground that have to stand up to wind, rain, and gravity.

i was thinking carborundum, diamond, or materials that aren't even semiconductors at room temperature, like zirconia. i don't think cadmium telluride will survive sunlight at the orbital radius of mercury, but plainly some solids do