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The solar cells used in calculators and satellites are also called photovoltaic (PV) cells (photo meaning "light" and voltaic meaning "electricity"), which convert sunlight directly into electricity.<ref name="hsw">Jessika Toothman and Scott Aldous, [http://science.howstuffworks.com/solar-cell1.htm "Photovoltaic Cells: Converting Photons to Electrons"] Howstuffworks.com, accessed May 2010.</ref> Photovoltaic cells are made of special materials called semiconductors such as silicon, which is currently used most commonly. When light strikes the cell, a certain portion of it is absorbed within the semiconductor material, and the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely. In short, the photovoltaic effect refers to photons of light knocking electrons into a higher state of energy to create electricity.<ref name="SciAm">[http://www.sciam.com/article.cfm?id=a-solar-grand-plan A Grand Solar Plan], ''Scientific American,'' December 2007.</ref>

Solar cells produce direct current electricity from sun light, which can be used to power equipment or to recharge a battery. The first practical application of photovoltaics was to power orbiting satellites and other spacecraft, but today the majority of photovoltaic modules are used for grid connected power generation. In this case an inverter is required to convert the DC to AC. There is a smaller market for off-grid power for remote dwellings, boats, recreational vehicles, electric cars, roadside emergency telephones, remote sensing, and cathodic protection of pipelines, known as [[microgeneration]].<ref name="mj"/>