How Do Solar Energy Panels Work?

Solar panels convert solar energy into electrical energy.

Solar panels are arrays of photovoltaic cells (PV cells), specially designed modules that convert solar energy into electrical energy. This conversion is made possible by the basic properties of matter.

Features

A PV cell contains two layers of a semiconducting material like silicon. One layer has been treated so that it contains excess electrons, while the other has been treated so that it contains a reduced number of electrons. The first layer is called an n-type semiconductor, while the second is called a p-type semiconductor. Some electrons migrate from the n-type layer into the p-type layer, creating an electric field across the junction between the two.

Function

Photons of light strike the p-type layer; these photons may pass through, be reflected or be absorbed. If a photon's energy is equivalent to or greater than the difference in energy between the orbital currently occupied by an electron and the next orbital available to it, it can absorb the photon and jump to the next orbital. The difference between the highest occupied orbital and the lowest unoccupied orbital is called the band gap. Electrons that gain sufficient energy to jump the band gap break free of the atom and under the influence of the electric field migrate into the n-type layer, driving a current we can use to power devices in businesses or homes.

Considerations

Much of the solar energy that strikes a solar panel is lost. If a photon doesn't have enough energy for an electron to jump the band gap, the photon will not be absorbed and will pass right through. If it has too much energy, on the other hand, the extra energy will be dissipated as heat. Many researchers are working on ways to make solar panels both cheaper and more efficient in the future.

References

• NASA: How Do Photovoltaics Work?
• "Chemical Principles, the Quest for Insight, 4th Edition"; Peter Atkins and Loretta Jones; 2008