[FredMitchell]

Originally Posted by Bay Kid

Solar panel fields are showing all over the country. Loss of farmland is my biggest fear. But what does the reflection back into the sky effect? Could this cause global warming?

It is sad to see the sheer ignorance exposed by all the folks who posted their "answers" to these two relatively simple and reasonable questions.

1. Reflection back into the sky is not really the way to look at this. Albert Einstein got a Nobel Prize for his paper describing the photoelectric effect - but most know him for his later work in relativity. The engineering outcome of that knowledge resulted in capturing electrons that are emitted when light hits metal in an electric circuit. (Solar panels). Once those electrons have completed some sort of electric circuit, some work has typically been done and the difference between the total energy of the emitted electrons and that work turns into heat. Roughly only 20% of the radiation hitting the panel gets turned into electrical energy. Most of the rest is absorbed causing the panel to heat up.
   
   Objects with a temperature above absolute zero emit electromagnetic radiation - you can look up black body radiation for more details, but it has been well understood since the 19th century. So the solar panel is always radiating energy in every direction, even at night! So, too, is everything around you, including your body.
   
   Also well understood is that different gases absorb different frequencies of light. The absorbed energy raises the temperature of the gases. The gas radiates in all directions. Some radiates out into space and some radiates into the earth. The balance of energy absorbed by the earth and the energy re-radiated affects the climate.
   
   One of the interesting and observable effects of radiation of heat at night occurs during temperatures where the air cools enough that moisture condenses on grass. Often times you will see this and notice that the grass under trees is dry or drier. That is because the black body radiation of the grass got blocked by the tree which re-radiated downward warming the grass. So the grass stayed warm enough that water vapor did not condense on the grass under the tree.
   
   

1. The cell, per se, won't cause global warming. It will reradiate pretty much like the earth's non-water-covered surface.

As to the farmland loss issue, solar cells are more efficient at generating energy than vegetation. So trying to generate usable energy from plant production, like, for example, ethanol is relatively more wasteful.