Completely side topic question - are there any studies on how much surface of the planet would need to be covered with solar to make a measurable impact on absorbing and/or reflecting enough sunlight to affect some cooling?
> Completely side topic question - are there any studies on how much surface of the planet would need to be covered with solar to make a measurable impact on absorbing and/or reflecting enough sunlight to affect some cooling?
I don't think solar will have any impact here. The whole point is to absorb the light (and energy), not to reflect it. That's one of the reasons solar panels appear black, not white: they're absorbing light.
If the alternative is coal, solar energy will warm the planet less, but it's not going to actively cool the planet the way you're describing.
Naively thought that by absorbing heat energy and transforming it into electric current, there was some cooling effect when compared to heating the surface of the planet.
There is localized cooling in the cell. Some photon energy that would have been thermalized immediately in a dark-colored simple absorber is carried away as electricity instead. But that electricity is, ultimately, used and thermalized somewhere else on Earth, so it doesn't have a cooling effect on the planet as a whole.
Additionally, the albedo of solar modules is lower than e.g. empty desert, so the net effect of installing a large solar array on such land is to slightly increase localized temperature. Accounting for increased albedo is why the IPCC's global warming assessment of utility-scale solar puts its warming impact a bit above that of rooftop solar. Rooftops are already lower in albedo, so adding solar modules doesn't darken them as much. Both rooftop and large desert-based solar have much lower warming potential than any form of fossil combustion, of course.
Earth's energy budget imbalance is around 0.6W m^2[0], while a passive cooling device developed by SkyCool Systems achieves 40W/m^2[1] of cooling power, so covering 5% of the land should be enough to balance things.
And 5% of either of those is an absolutely stupendous amount of space.
In any case, those cooling devices aren't needed if all you want is to block the sun - a mirror works better. Those cooling devices are for heat generated from behind the device.
Solar panels in and of themselves make the surface slightly warmer, not cooler. Their beneficial effect is through preventing the emission of more CO2 into the atmosphere.
