The Science Behind Photovoltic Electric Generation
Photovoltaics depend on the basic properties of semiconductor materials that can transform solar energy into electricity. The properties of these semiconductors are formed at the atomic level.

Photovoltaics depend on the electrical properties of certain materials, known as semiconductors, which allow them to transform sunlight into electricity. While a number of materials have this semiconductor property, the one most commonly used in photovoltaics is silicon. On its own, silicon is actually very resistant to electrical current, but its properties can be altered by doping it, or combining it with small amounts of other materials that make it receptive to either a positive or negative electrical charge.

When a positively charged layer of silicon is placed against a negatively charged layer of silicon, it forms an electrical field through which electrical charges can pass. Sunlight, carrying solar energy creates this charge. By connecting the silicon to a conductive metal, this charge can be concentrated into an electrical current, which can then be fed to any device that uses electricity.

A Material that Translates Photon Energy into Electricity

The key properties of semiconductor material are determined at the atomic level. Each atom is composed of three types of particles: protons, neutrons, and electrons. Protons, which have a positive electrical charge, and neutrons, which have no electrical charge, form the nucleus, or core of an atom. Electrons, which each have a negative electrical charge, swirl around the nucleus in one or more layers of "shells", shown in the diagram as rings. Different types of atoms are defined by their unique number of protons, neutrons and electrons. It is the electrons that we are particularly concerned with, as these can be disengaged from certain atoms to collectively form an electrical charge.