You have a dark radiating side on the back of the solar panels. You can spread the GPUs around the solar panels. All the energy in comes from the sun so the temperature should be much the same as any dark panel like object floating in sunlight in space.
Or something like that - the temperature goes hot and cold as the things go into light and shadow so they have insulation.
No, temperature does not decrease significantly when objects are in the shadows, unless hey stay there for a long time. Even when they don’t get energy from solar radiation, they still dissipate it by radiative transfer, which is very inefficient. So they cool down slowly.
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