system
Given the following post, respond as if you're commenting on Reddit:
human
Could solar power be used to cool the Earth?

Probably a dumb question from a tired brain, but is there a certain (astronomical) number of solar power panels that could convert the Sun's heat energy to electrical energy enough to reduce the planet's rising temperature?

EDIT: Thanks for the responses! For clarification I know the Second Law makes it impossible to use converted electrical energy for cooling without increasing total entropic heat in the atmosphere, just wondering about the hypothetical effects behind *storing* that electrical energy and not using it.
gpt
There's a lot of different physics bundled into this question. The technical physics answer to your question is 'no,' but the real answer from a practical perspective is 'yes.' 

First, the amount of energy arriving from the sun every second is absolutely ginormous, about 10^17 Watts of power. If you could collect all of this energy (like by covering the world in solar panels and batteries) you'd only need about an hour of sunlight to power civilization at current usage for a year. So all solar panels we currently have only collect a tiny fraction of a percent of incoming solar flux. 

But there's an important thing here- collecting sunlight to use will generally heat the planet more than it will cool it. Yes, that energy does temporarily end up in batteries, but that energy is still on the earth and using it will eventually convert it to heat. That's just the laws of thermodynamics, used energy ends up dissipated as heat (it's why your laptop gets hot, especially so when it's using a lot of energy like when you're playing a video game). 

Really, if you wanted to cool the planet you'd want to reflect sunlight back to space so that it never gets absorbed. This is what climatologists mean when they talk about the 'albedo' of different things. It's like a measure of the 'whiteness,' or how much light a thing reflects. Clouds are great at reflecting sunlight back to space, and so are the ice caps. Concrete, farmland, and especially solar panels are very bad at reflecting sunlight. In principle, if you build solar panels on a surface that has a worse albedo then you'll be effectively cooling the planet. The surface will reflect more light, and will also generate electricity sparing us fossil fuel burning.

And that's the final point- fossil fuels. Ultimately, if you want to cool the planet, you'll want to remove CO2 from the atmosphere. These gasses increase the atmosphere's opacity to infrared light, trapping more heat from the sun and raising the surface temperature like a blanket. That's really the primary thing driving the heating. So in the most relevant sense, solar panels are good for cooling the planet because they replace traditional fossil fuel burning energy sources.