Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV) , or indirectly using concentrated solar power ( CSP). Of concentrated solar power systems use lenses or mirrors and tracking systems to focus a large part of the sunlight into a small beam. Photovoltaic convert light into an electric current by using the photoelectric effect.Commercial CSP plants were first developed in the 1980s. The 354 MW SEGS CSP plant is the largest solar plant in the world , located in the Mojave Desert in California. Other large CSP plants include Solnova solar power station (150 MW) and the Andasol solar power plant (150 MW) , both in Spain . The Agua Caliente over 250 MW of solar projects in the United States , and the 221 MW solar park in Charanka India are the world's largest photovoltaic power plants.Solar power is the conversion of sunlight into electricity. Sunlight can be converted directly into electricity using photovoltaics (PV) , or indirectly with concentrated solar power (CSP ), which normally focuses the sun's energy to heat water which is then used to provide energy . Other technologies also exist, such as the Stirling engine dishes which use a Stirling cycle engine to power a generator . Photovoltaics were first , and still are, used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic generator. They are an important and relatively inexpensive source of electricity where the electricity grid is annoying , a disproportionate cost to connect , or simply unavailable.Concentrating solar power systems (CSP ) use lenses or mirrors and tracking systems to focus a large part of the sunlight into a small beam. The concentrated heat is used as heat source for a conventional power plant. A wide range of concentrating technologies exists: the most developed are the parabolic trough [ discuss ] the linear Fresnel reflector concentration , the Stirling dish and the tower of solar energy collectors . Various techniques are used to track the sun and focus light. In all these systems a working fluid is heated by the concentrated sunlight , and is then used for power generation or energy storage storage.Thermal can efficiently generate electricity 24 hours.
A parabolic trough consists of a linear parabolic reflector that concentrates light onto a sensor positioned along the focal line of the reflector receiver . The receiver is positioned above the middle of the parabolic mirror and tube is filled with a working fluid. The reflector is made to follow the sun during the day by tracking along a single axis . Systems of parabolic trough offer the best land-use factor of any solar technology.The SEGS plants in California and Acciona Nevada Solar One near Boulder City, Nevada are representatives of this technology.Compact Fresnel reflectors linear are CSP- plants which use many thin strips instead of parabolic trough mirrors to concentrate sunlight onto two tubes with working fluid. This has the advantage that flat mirrors can be used which are much cheaper than parabolic mirrors , and that more reflectors can be placed in the same space, allowing more of the available sunlight to be used . The concentration of linear Fresnel reflectors can be used in large or more compact plants.The Stirling solar dish combines a parabolic concentrating dish with a Stirling engine which normally drives an electric generator . The advantages of Stirling solar over photovoltaic cells are higher efficiency of converting sunlight into electricity and longer life. Parabolic systems give the best performance among CSP technologies.The 50 kilowatts Big Dish in Canberra, Australia is an example of this technology.A solar tower system uses a tracking reflectors ( heliostats ) for focusing light onto a central receiver at the top of a tower. Power towers are more cost effective , offer higher efficiency and better capacity energy storage among CSP technologies . The PS10 and PS20 solar solar power are examples of this technology.A solar cell or photovoltaic (PV) cell , is a device that converts light into electricity using the photoelectric effect. The first solar cell was built by Charles Fritts in the 1880s . The German industrialist Ernst Werner von Siemens was among those who recognized the importance of this discovery. In 1931 , German engineer Bruno Lange has developed a photo cell using silver selenide in place of copper oxide , although the prototype selenium cells converted less than 1 % of the incident light electricity. Following the work of Russell Ohl in the 1940s , researchers Gerald Pearson , Calvin Fuller and Daryl Chapin created the silicon solar cell in 1954. These early solar cells cost 286 USD / watt and reached efficiencies of 4.5-6 %.
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