how exactly is that?
I could see their darkness and reflective value a problem vs. soil or foilage, but put on a tar roof I'd say they minimize that...and in the US most electrical plants are coal or oil so they'd be reducing the increased need for more plants...
'splain yoself.
I'm in your neck of the woods for a few days... a bit south in Easton.
Well... what is a greenhouse? It lets solar energy in, the energy is used or stored, converted to heat, and the heat is somewhat trapped. A solar cell accomplishes the same thing. It takes solar energy in, converts it to electricity, and darn near every electric appliance is air cooled and does not evaporate water. Perfect greenhouse. If the planet were covered with solar cells it would bake it like an electric oven. Why?
It is like a house... if you turn on any appliance in a house, even the refrigerator, it will heat the house up. So if you put solar cells on top of the house and power anything inside of the house... you will be heating up the house. Make sense?
The reason the planet would bake is a little more deceptive... basically the atmosphere is somewhat insulative at lower temperatures just like the walls and roof of the house. When sunlight hits things like pavement, roof tops, or cars, it heats them up above atmospheric temperature. Being hotter, those things are going to radiate heat with a stronger and different EM frequency distribution. They will radiate faster and better into the night sky than something at room temperature. In the night the pavement, the roof top, and the car often cool below the atmospheric temperature. So in a desert for example where there is low water it might be very hot in the day, but it is also going to be colder at night. There are more extreme temperature differentials between day and night in a desert (low water) than say some place like Seattle where there is a stronger water cycle... the temperatures are milder in Seattle.
So my point is that even in a desert there is ample cooling by radiative cooling. Rather than just heat the atmosphere up, the solar targets re-radiate the energy right back into space. In a desert there is wasted energy. A solar cell in the desert is going to harness that energy. As you harness that energy instead of heating up the ground hotter than atmosphere, it will instead heat up the atmosphere. That lesser atmospheric temperature is harder to expel off the planet than the energy that was absorbed by the hot sand, (pavement, rooftop, etc...) and then jettisoned unused into the night sky. By using the energy with a solar cell, we've increased the background atmospheric temperature... which is harder to get out of the house.
So how do we use energy AND cool the house? To cool a house requires A/C or a swamp cooler and good air flow, right? Well, how does the A/C work? It works by alternating the phase of Freon (or water), for example, between a gas and a liquid. The Earth's water cycle is identical. If you want to cool the house, you need to drive the Freon cycle. If you want to cool the planet, you need to drive the water cycle. The problem is, nothing a solar cell is going to power is going to really drive the water cycle. People don't use electricity that way... they don't cool their computers by evaporating water for example. Using a solar cell is like turning on the oven in the house... is that going to heat up the house or cool it down? Put solar cells on the roof of a building... you will be contributing to global warming. I kid you not.
Plant trees on the roof of a building... then you will be contributing to global cooling, removing CO2 from the atmosphere, and storing and preserving energy delivered by the sun for future use. Plants evaporate water and thus drive the Earth's A/C. Solar cells and whatever they power... do not.
