Solar Power Cell

Photovoltaic solar panels are composed of a number of solar energy cells.

A solar power cell converts light into electricity and is known as a photovoltaic cell.

Photovoltaics convert the light rays from the sun into energy that can be used to power your household appliances.

This differs from passive solar energy which uses the heat and light from the sun without changing it's form.

The first solar power cell was invented by Charles Fritts in 1883. Since then, many scientists have worked to improve upon his invention. Known as solar energy, this form of renewable energy could someday replace coal and natural gas as the dominant energy source for homes, businesses, and other places that require electricity.

In order to harvest energy from the sun, a solar power cell must be made from a material that allows light waves from the sun to be absorbed.

In 1883 Fritts used selenium coated with gold as a semiconductor, which is a place where positive and negative ions meet. While this proved that generating energy from the sun was possible, it was very inefficient.

The silicon solar power cell

In 1941 the first silicon solar cell was created by Russell Ohl. Silicon proved to be a much better semiconductor and is still used today in solar cells and computer components. Ohl was only able to create energy conversions of less than one percent, however in 1954, more advances were made in order to increase energy conversions.

Three scientists, Calvin Fuller, Gerald Pearson, and Daryl Chapin, designed solar panels using silicon as a semiconductor and were able to create energy conversions of six percent. By using more than one panel, they were able to create more energy.

How a solar power cell works.

Solar cells have reached a level of efficiency that allows us to power homes, equipment, satellites and even cars.

How do solar energy cells capture light energy from the sun?

Solar energy cells are made up of two layers called the p-layer (positive charge) and the n-layer (negative layer). When these layers are sandwiched on top of each other they form an electric field.

Magnets are a good example of how these layers work in relation to each other. Because the energy harvested from the sun reaches the cell in the form of light energy, the first step is to capture as many particles within the light as possible. These particles, called photons, are absorbed by solar cells and come into contact with electrons that are contained within atoms found on the cell. Once a photon and electron meet, the electron is allowed to roam all over the solar cell instead of remaining with the atom. This leaves a 'hole' in the atom.

Because electrons have a negative charge they are most likely to move to the n-layer leaving holes in the p-layer. As electrons move through these holes, an electrical current is formed. As electrons move through the holes, they make room for newly charged electrons.

When electrons reach the point where the p-layer and the n-layer meet, which is called the junction, the electrical current is charged. It is this current that is harvested and used to generate energy that we use in our homes.

Here's a photovoltaic cell animation that we really like.

In order for a solar power cell to function properly the electrons must move quickly through the holes so they don't bump into one another and lose their speed. When electrons touch, they become stagnant again. By placing electrons as close to the junction as possible, crowding should not occur as often. Once a cell begins this process, it should be able to repeat it throughout the day as long as they are in a position to absorb the sunlight.

Solar Panels become inactive when placed in a position where no light strikes them. Without the photons from the light electrons would stand still in the atom and a continuous electric current would not be possible. The more direct light that strikes the cell the more power the cell is able to make.



For more solar power cell information check out our pages on solar energy history