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What is a Solar Cell?

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A solar cell is a device that is used to convert sunlight into electricity. Such cells take advantage of a physical phenomenon called the ‘photovoltaic effect’ which basically postulates that certain materials produce small amounts of electricity when exposed to sunlight. The amount of electricity produced by a single solar cell is usually too minute to be useful. So typically, multiple photovoltaic cells are connected together into a single larger ‘solar panel’ or ‘solar module’ in order to generate usable energy. Most commercially available solar panels are capable of generating about 12 volts of electric current on a full charge. Solar-powered devices often use multiple solar panels in order to generate the electricity they need for their specific purpose. The number of solar panels needed for an application can vary depending on the number of individual solar cells in a solar panel, or by the sort of application that it is needed for. For example, a solar-powered water-heating system will use far more solar panels than a solar-powered lighting system.

The amount of electricity generated by a solar cell is directly dependent on the amount of sunlight that falls on it. The more direct and bright the sunlight is the more voltage that is generated by a solar cell. A vast majority of solar cells in use today are based on silicon, which is a semi-conducting material capable of absorbing photons from sunlight and converting it to electric current. The electricity generated by a solar panel is converted into alternating current (AC) or direct current (DC) and stored in battery packs or transmitted over power lines for residential or commercial consumption.

Solar cells have come a long way since the photovoltaic effect was first discovered in 1839 by Edmund Becquerel, a nineteen year old French physicist. The first solar cell based on the photovoltaic effect worked at just 1 percent efficiency meaning that it was able to convert just one percent of the solar energy that was falling on it, to electricity. In the mid-1950’s Bell Labs discovered a way to make silicon much more photo-sensitive thereby paving the way for most modern solar cells. Since then, numerous advances in semi-conductor technologies have resulted in solar cells that are capable of operating at close to 35 percent efficiency. Most of the advances have focused on finding ways to make silicon more sensitive to light.

However, over the years scientists and researchers have experimented with other semiconducting material for making a solar cell. In the late 1980’s for instance, scientists experimented with solar cells made of a material called gallium arsenide. Solar cells made from the material were capable of operating at efficiencies in excess of 20 percent. During the same decade, researchers also showed how they could improve the efficiency of a solar cell by focusing sunlight on them through the use of lenses. More recently, manufacturers have begun using techniques such as vapor deposition and electroplating to try and manufacture super thin cells based on material such as cadmium telluride and amorphous silicon. The goal behind using such materials and techniques is to bring down the costs associated with mass-producing solar cells. Efforts are currently underway to boost energy efficiency of such solar cells through the application of new light focusing and thermal techniques.