I know the answer to this! And when it is spelled out, you will slap yourself a bit. When you cover a satellite with a dark material, it absorbs heat from the sun. As there is also waste heat from the electronics, payload etc inside the satellite, cooling the systems becomes a really big deal. On the ground, we can just run air over the stuff, and with a big enough fan and heat sink the problem goes away. But wrapping a satellite in a reflective blanket ALSO has issues as it removes so much heat from the electronics bus that things can freeze! So, most of the satellites you see will have a bright reflective coating on one side of the spacecraft, and a dark covering on the other. This is one reason the Shuttle had a white top and a dark bottom; the different reflective surfaces were used for temperature control.
To add onto this, most, if not all, satellites have a Faraday cage that they are wrapped up in. This helps shield the electronics from the stray EMF and electron dumping from the solar wind, the magnetic induced currents from the earth's magnetic field and even the currents generated from the temperature differences on the hot and cold side of the satellite. You want all that EMF outside the satellite body and not in the electronics bays. Solar panels, by the nature of how they function, also have to dump a significant amount of heat into space to prevent damage to the circuits. These, for example are used to cool the solar panels on the ISS. These panels at a right angle to the rotating solar panels have tubes full of ammonia that radiate heat into space then pump the cooler liquid back through the solar panels.
When I was bored and looking into making a micro sat, they explained how to use heat sinks exposed to the outside of dead space and reflective coverings to keep those exposed bits at -190F to -250F as a way to dispose of the heat of the internal electronics. Turns out that the CCD's that are radiation hardened enough to do useful work in space take a lot of power and demand a crazy amount of cooling to get rid of excess noise. The even more interesting thing is that an 85mm earth imaging satellite (or even better a space facing one) including launch would run about 150K US. And it would fit into existing micro sat frames.
Dealing with the thermal and EMF aspects was a fun rabbit hole to go down until I could not find anyone willing to help me finance a space telescope; hell 150K is hookers and blow money for some people, right? Then the Planetary Resources people came out and crushed my satellite dreams, so I gave them money instead.