That's some food for thought. Would a field covered in panels be warmer or cooler than the same field without? On the one hand, the albedo of a panel is super low. That's sort of the point as they don't want any of the sunlight lost. On the other hand, the panels are thin and have little heat retention, so one would expect them to shed whatever heat they build up during the day quickly at night compared to the ground. I suspect the shading effect on the ground would win out in the end, but I'm not sure?

Heat dissipation is an issue for solar panels, to the extent that some have tried deploying floating panels on a lake to get a better cooling effect from the water. Water bodies already have extremely low albedo, so the panels would likely have little effect in that regard. I suppose they might reduce evaporative cooling depending on how thorough the coverage is?

There is also research into materials with radiative cooling properties and whether these can be combined into PV cells. Radiative cooling exploits the infrared transparency of the atmosphere at certain wavelengths that thankfully aren't being blocked by greenhouse gases. I think this is a great idea and could reduce urban heat islands and save energy on A/C in hot climates, essentially for free.