Photovoltaic energy, also known as solar electric energy, is produced when a photovoltaic (or solar) cell collects sunlight and converts it directly into electricity. Photovoltaic energy is used to power a variety of things, from a small solar calculator to entire households and even Earth-orbiting satellites.
The Dawn of Solar Power
Photovoltaic energy was first discovered in 1876, when Richard Evan Day and William Grylls Adams observed that selenium generated an electrical current when exposed to light. The first selenium cells did not produce enough energy to power electrical equipment. In 1953, Gerald Pearson, a scientist at Bell Laboratory, discovered that silicone could be used to create a photovoltaic cell that could power small electronics. After discovery, photovoltaic technology steadily evolved into the solar cells used today.
Photovoltaic cells are composed of a semiconducting material -- most often silicon -- in which the process of converting sunlight into energy occurs naturally. To power small electronics, only one or two cells may be needed. To power something larger, such as a household, cells can be linked together in modules, which can in turn be connected to form an array. The size of the array can vary, depending on what it will be used to power.
How They Work
Photovoltaic cells convert sunlight into electricity via the photoelectric effect. When photons strike the surface of a cell, they are absorbed and cause some of the electrons present in the atoms of the material to be knocked loose. These freed electrons create an electrical charge on the surface of the material, which is then converted into an electrical current by conductors attached to the photovoltaic cell. The more sunlight that is collected by the cell, the more power it will generate.
In the 1950s and 1960s, the first photovoltaic cells were manufactured and used to power the electrical operation of Earth-orbiting satellites. By the 1970s and 1980s, solar cells became more widely available and were used to power small, everyday devices such as calculators and watches. Photovoltaic cells are used today to power a variety of things, from solar garden lamps to entire households.
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