How in the World Can a Little Solar Cell Make Electricity?
Generating your own electricity from sunlight is a marvelous thing. We hear so much about the damaging effects and rising costs of the fossil fuel industry. One has to wonder why more people aren’t buzzing about the cleanness and simplicity of converting sunlight to electricity.
In 7th grade I had a great science teacher. He was great because he thoroughly understood his subject. He knew it so well he could explain it in the most basic understandable terms. When Mr. Bielski taught us something, there was no child left behind. As a result, our love for science grew.
Now I’m a grown-up student, learning from hands on experience. Solar power has been part of my life for the past 16 years and I wouldn’t trade it for all the electric bills that never came. I started with one of the most basic systems. It cost me only a couple of hundred dollars since some components were second-hand. It wasn’t what you’d call a power-house, but it helped me to understand solar power from the ground up. My old science teacher would be proud.
I must confess that at the beginning I really didn’t understand how the solar cell itself was working. I only knew that if I put my used solar panel array face front to the sun, it would put electricity into my cheap-o batteries and I could run DC lights, a radio, my computer and a few other things that made our new home in the middle of nowhere more homey.
Now I realize that knowing how those little solar cells have been cranking out the juice all these years is worthwhile. I’m building my own solar panels now so handling these little wafers has made me curious about how they keep working their magic.
It turns out that every solar cell is like a sandwich. In the center is a thin slice of highly purified silicon. The silicon sandwich has two types of bread. On one side is boron and on the other side is phosphorus. Sounds yummy.
It just so happens that when this sandwich is bombarded by sunlight, some of the excess electrons are knocked off the side facing the sun. This creates a voltage difference between the two sides of the sandwich, which makes the electron very unhappy. They like to be balanced. So, the excess electrons try to go through the silicon to get to the side of the sandwich where there are fewer electrons. Unfortunately for them, that’s not easy because the silicon puts up resistance.
When we construct a solar panel, we string the solar cells together (usually 36 of them) with a type of metal ribbon, which acts like a wire. The unhappy crowded electrons find it easier to move down the metal ribbon than to fight their way through the silicon. When we attach a DC electrical device, such as a 12-volt light, to the wires coming off these metal ribbons, the electrons flow happily around the circuit and voila — there is light!
Does this matter? I think it does. When we realize how simple the solar cell is and how it makes electricity in such an uncomplicated way, we tend to think that the rest of the solar electric system can be understood, too… And it can.