Only if placed above high albedo surfaces. And when placed above existing grass several times less than any other option except wind/tidal.

A solar panel above asphalt or concrete provides a net increase in albedo. And there is more than enough to provide the required solar share of energy to provide all our needs (with the other half provided by wind).

More or less than fossil fuels?

Irrelevant, the point is that they don't increase albedo so deploying absurd amounts of them won't cool the atmosphere.

The whole point of solar panels is to offset energy which would be produced (easier) with fossil fuels while heating the atmosphere. They very well might cool the atmosphere more, they might not. That seems pretty relevant.

What about the greenhouse effect?

More or less than nuclear?

Whether it’s with solar or nuclear (or wind, hydro, geothermal, or what have you) I think it’s clear that the fossils need to be replaced foremost.

Putting solar panels in deserts is a very stupid use of those solar panels, in any case.

The only reason solar farms are placed in deserts is that pig-ignorant investors love the idea, so there are oceans of money earmarked for it.

What's wrong with putting solar panels in deserts? Increased maintenance? Distance from civilization?

They also loose efficiency with heat, about 0.5%/°C, so cheap panels can be 25% less efficient.

They gather dust, which can cut output 50%. That is on top of the heat induced loss of conversion efficiency, and reduced panel life.

And, yes, you need to build transmission lines.

They go better in pastures and floating on canals and reservoirs.