But, isn't the albedo of a solar panel farm still way dark? It means the radiation is still being captured rather than reflected back up.

You're not looking at the albedo of the solar panels in isolation though, you're comparing it to asphalt and cars. Typical solar panels have an albedo of ~0.3. Asphalt around ~0.05.

Capturing the radiation to convert it to electricity is the whole point of solar panels.

Even if it was just 0 albedo no generation, irradiation on whatever's parked beneath would be cut in half plus rest of (re-)radiation converted into far-ir. This is not unuseful. Just don't mandate this kind of thing in places where parking lots have to be cleaned up with bulldozers in winter.