Photovoltaic Cell

A photovoltaic cell, often called a solar cell, converts the energy in light directly into electrical potential energy using a physical process called the photovoltaic effect. Photovoltaic cells are used to produce electricity in situations where they are more economical than other power generation methods. Occasionally, they are used as photodetectors.

The photovoltaic effect has been known since Edmund Becquerel observed light-induced currents in a dilute acid in 1839. Explanation of the effect depends on quantum theories of light and solids that were proposed by Planck in 1900 and Wilson in 1930.

The first solid-state photovoltaic cells were designed in 1954, after the development of solid-state diodes and transistors. Since then, the number of applications of photovoltaic cells has been increasing, the cost per watt of power generated has been declining, and efficiency has been increasing. Enough photovoltaic modules to provide 50 MW of power were made in 1991. The production rate appears to be increasing by about 20% each year.

A custom-designed solar powered desalination system in Jeddah, Saudi Arabia. It is composed of 210 photovoltaic modules that supply 8 kilowatts of power (peak) for conversion of highly saline water into fresh drinking water. Mobil Solar Energy Corporation/Phototake NYC. Reproduced by permission.

Photovoltaic cells have been used since 1958 to power many satellites orbiting the earth. On earth, they are used in remote areas where the cost of transporting electricity to the site is costly. Their use is one of a variety of alternative energy methods being developed that do not depend on fossil fuels. They are also used for low-power mobile applications such as hand-held calculators and wrist watches.