Solar Energy-
It seems that you can find solar cells everywhere if you just look; on calculators, sidewalk lights, and some houses. The sun, depending on who you ask and where your at, produces about 1,000 watts of energy per square meter. This is enough energy to power the standard 75 watt light bulb for 13 hoursand 20 minutes. The problem is that even a good solar cell only collects about 15% of the sun's energy. This is only 150 watts, or two hours for your light bulb.
Using semiconductors a photovoltaic cell can be built. Semiconductors are solid substances that's conductivity is between that of a conductor(copper) and insulator(glass, plastic.) A photovoltaic cell is what we use to capture the sun's energy and transform it into electricity. The most commonly used semi conductor in solar cells is silicon.
To see how silicon works in a solar cell we need to understand the basics of an atom: Atoms all have a nucleous, which is surrounded by an electron cloud. In this cloud electrons orbit around the nucleous. The atom is stable when its inner orbit contains two electrons and each one after that contains eight. An atom tries to become stablizes by attaching to the outer layers of other atoms. Silicon does this, because, with only 14 electrons, its outer layer has only three. |  |
Photovoltaics take place when the energy from the sun, absorbed by the semiconductor, knocks electrons off the outer layer. This allows them to flow about freely. Solar cells all have at least one electric field that lets the electrons flow in a certin direction, causing a current.
