How does
Photovoltaic
Power Work?


Physics and chemistry are what we use to generate power using sunlight. If you remember from chemistry, electrons are small particles that orbit around an atom. Electrons have a negative charge to counteract the positive charge of the protons in the nucleus. Moving electrons are actually how electricity works.

Due to their negative charge, electrons will flow towards a positive charge. That movement brings energy with it; we call that energy electricity.

Enter light into the equation. Physics tells us that light travels as small particles called photons. Photons generated by the sun have a certain amount of energy to them when they reach the surface of the earth. If that energy happens to be the right amount, and also happens to collide with an electron, it can knock the electron lose from its atom.

Engineers build solar cells from materials designed to do this specifically. The solar cells are engineered from materials that easily allow their electrons to be knocked loose so they can flow and create electricity.

Solar Cell
Efficiency


One of the major engineering challenges with solar cells is being able to make them more efficient. Right now the most efficient ones only convert about 30 percent of the light energy to electricity. Why? Because sunlight is actually seven types of light combined.

Think of a rainbow. Red, Orange, Yellow, Green, Blue, Indigo and Violet are the colors of the rainbow, but the colors actually tell us something about the nature of the light. Each color represents different amount of energy contained by the photon of that color. Red photons have less energy than orange ones, orange less than yellow and so on up the spectrum. This is important because the solar cell must be designed to accept a specific color, or energy, of the spectrum.

To design a more efficient cell, engineers must figure out a way to make the cells accept wider ranges of the spectrum.

Area
Required


The last thing we really need to generate power is space to put the solar cells. The larger the area that is covered, the more power can be generated. There is no way to "stack" solar cells. They must be exposed to a large amount of light over a large area.

This is why using roof tops, unused farm land and other spaces that are not utilized is critical if solar power is to become a reality.