Solar Power

Contents 1.Introduction 2.History 3.Applications 4.Solar Panels 5.How PV cells work 6.Other applications 7.Top Countries 8.EXIT

1. Introduction Solar energy is a type of renewable energy which comes directly from the Sun. This energy drives the climate and weather and supports virtually all life on Earth. Solar energy technologies harness the sun's energy for practical ends. These technologies date from the time of the early Greeks, Native Americans and Chinese, who warmed their buildings by orientating them toward the sun. Modern solar technologies provide heating, lighting, electricity and even flight. Solar power is used synonymously with solar energy or more specifically to refer to the conversion of sunlight into electricity. This can be done either through the photovoltaic effect or by heating a transfer fluid to produce steam to run a generator. Back

2. History Russell Ohl Back The photovoltaic effect was first recognised in 1839 by French physicist Alexandre-Edmond Becquerel. However, it was not until 1883 that the first solar cell was built, by Charles Fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions. The device was only around 1% efficient. Russell Ohl patented the modern solar cell in 1946. Sven Ason Berglund had a prior patent concerning methods of increasing the capacity of photosensitive cells. The modern age of solar power technology arrived in 1954 when Bell Laboratories, experimenting with semiconductors, accidentally found that silicon doped with certain impurities was very sensitive to light. Russell Ohl Back

3. Applications Solar cells Back Solar cells have many applications. Individual cells are used for powering small devices such as electronic calculators. Photovoltaic arrays generate a form of renewable electricity, particularly useful in situations where electrical power from the grid is unavailable such as in remote area power systems, Earth-orbiting satellites and space probes, remote radiotelephones and water pumping applications. Photovoltaic electricity is also increasingly deployed in grid-tied electrical systems. Solar cells The first spacecraft to use solar panels was the US satellite Explorer 1 in January 1958. This milestone created interest in producing and launching a geostationary communications satellite, in which solar energy would provide a viable power supply. This was a crucial development which stimulated funding from several governments into research for improved solar cells. Back

4. Solar panels Photovoltaics, or PV for short, is a solar power technology that uses solar cells or solar photovoltaic arrays to convert light from the sun directly into electricity. Solar cells produce direct current electricity from light, which can be used to power equipment or to recharge a battery. A new photovoltaic "thin film" technology is being pioneered by a Californian company that allows cells to be mass produced by printing them on to aluminium film at a fraction of the cost of existing techniques. At December 2007 the company claims it can achieve costs of USD $0.99 a watt which is comparable to coal produced electricity. Back

5. How PV cells work Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. Basically, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely. PV cells also all have one or more electric fields that act to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, we can draw that current off to use externally. Back

6. Other applications Solar thermal energy Is a technology for harnessing solar energy for heat. This is very different from solar photovoltaics, which convert solar energy directly into electricity. Solar thermal collectors are characterized by the US Energy Information Agency as low, medium, or high temperature collectors. Low temperature collectors are flat plates generally used to heat swimming pools. Medium-temperature collectors are also usually flat plates but are used for creating hot water for residential and commercial use. High temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production. Next

Solar power tower The solar power tower (also known as 'Central Tower' power plants or 'Heliostat' power plants or power towers) is a type of solar furnace using a tower to receive the focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun's rays upon a collector tower (the target). The high energy at this point of concentrated sunlight is transferred to a substance that can store the heat for later use. Next

Solar vehicles Development of a practical solar powered car has been an engineering goal since the 1980s. Solar cars are generally powered by PV panels positioned on the vehicle. The center of this development is the World Solar Challenge, a biannual solar-powered car race in which teams from universities and enterprises compete over 3,021 km across central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 km/h. The 2007 race included a new challenge class using cars with an upright seating position and which, with little modification, could be a practical proposition for sustainable transport. The winning car averaged 90.87 km/h . Back

7. Statistics Germany->2,863MV France Japan South Korea USA Top contries using solar power Germany->2,863MV France Japan South Korea USA Thailand Switzerland Spain Austria China Luxembourg Australia World ->5,862MV the Netherlands EU->3,220 MV Italy Back

Coordonated by: Mr.Schnabel Dieter made by: Isac Bianca-Mihaela Voda Dragos-Ioan Coordonated by: Mr.Schnabel Dieter