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SOLAR CELLS AND SOLAR PANELS - SOLAR NAVIGATOR WORL... http://www.solarnavigator.net/solar_cells.htm SOLAR CELLS HOME | BIOLOGY | FILMS | GEOGRAPHY | HISTORY | INDEX | INVESTORS | MUSIC | SOLAR BOATS | SPORT It's incredible that we've come this far. We can catch the Sun's radiant light energy and convert it into electrical energy. It's nothing new of course. Nature has been capturing the energy in light for millions of years. Each leaf is a form of solar cell, producing energy for plants and
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    SOLAR CELLS   HOME|BIOLOGY|FILMS|GEOGRAPHY   |HISTORY|INDEX|INVESTORS|MUSIC|SOLAR BOATS|SPORT   It's incredible that we've come this far. We can catch theSun'sradiant light energyand convert it into electrical energy. It's nothing new of course. Nature has beencapturing the energy in light for millions of years. Each leaf is a form of solar cell,producing energy for plants andtreesto grow in a chemical process known asPhotosynthesis.   Solar panels power satellites   SPACE AGE TECHNOLOGY - Solar cells, also known as Photo Voltaic Cells, were rapidlydeveloped to provide electrical energy for space missions. The beauty of solar cells isthat provided the Sun shines, they keep on producing free electricity. Well, sort of free. Solar panels are still expensive to manufacture. It is the high purchase priceand installation cost that effectively limits their use.   There are many types of solar cell. Polycrystaline (more than one crystal),monocrystaline and thin film. Monocrystaline is presently the most efficient atconverting light energy into electricity. Sometimes as high as 20% but more usually15%. A monocrystaline cell is made from a thin slice cut from a single crystal of silicon. A grid of metal is then embedded over the wafer ending in the contacts andother layers added. Thin film cells are plated onto a plate of glass. They are muchcheaper to produce, but only around 5% efficient and heavy. Vehicle designers willnormally want to capture as much energy as possible for a given area and weight.A single cell is not of much practical use, producing less than a volt. Several cells haveto be connected in a series of cells to produce a useable voltage. The voltage increasesproportionally. 10 cells connected in series will produce about 7.5 volts. 20 cells 15volts and so on. A number of cells (a battery) linked and mounted together is knownas a solar panel. SOLAR CELLS AND SOLAR PANELS - SOLAR NAVIGATOR WORL...http://www.solarnavigator.net/solar_cells.htm1 of 196/28/2013 12:19 PM    HOW MUCH POWER - The Sun's energy reaching the surface of our planet is roughly1 kilowatt per square meter. Before entering our atmosphere it is about 20% more:1.2 kilowatts. That's why astronauts always look so bright. At 15% efficiency 10panels each measuring 1meter by 1 meter would power 1 1/2 bars on an electricheater. 20 panels would power an electric kettle. This of course assumes that the sunis shining. Just imagine how many panels Solar Navigator needs to cross an ocean?Why not try and guess the area of panels on Solar Navigator.   The supply of solar energy is both without limit and cost; solar energy will pour down on us long after we run out of fossil fuels.   Charles Fritts, 1886, inventor of the first selenium solar panel.   Example of commercially available products: Solar Solar Kits Solar Gadgets SOLAR CELL MANUFACTURERS WORLD WIDE   Essentially, solar panels are devices that convert light into electricity. They are calledsolar after the sun or Sol because the sun is the most powerful source of the light touse. They are sometimes called photovoltaics which means light-electricity . Solarcells or PV cells rely on the photovoltaic effect to absorb the energy of the sun andcause current to flow between two oppositely charge layers.   Solar cell   Photovoltaics Photovoltaic (or PV) systems convert light energy into electricity. The term photo is astem from the Greek phos, which means light. Volt is named forAlessandro Volta(1745-1827), a pioneer in the study of electricity. Photo-voltaics, then, could literallymean light-electricity. Most commonly known as solar cells, PV systems are alreadyan important part of our lives. The simplest systems power many of the smallcalculators and wrist watches we use every day. More complicated systems provideelectricity for pumping water, powering communications equipment, and even lightingour homes and running our appliances. In a surprising number of cases, PV power isthe cheapest form of electricity for performing these tasks.   Photovoltaic cells convert light energy into electricity at the atomic level. Although firstdiscovered in 1839, the process of producing electric current in a solid material withthe aid of sunlight wasn't truly understood for more than a hundred years. Throughout SOLAR CELLS AND SOLAR PANELS - SOLAR NAVIGATOR WORL...http://www.solarnavigator.net/solar_cells.htm2 of 196/28/2013 12:19 PM  the second half of the 20th century, the science has been refined and the process hasbeen more fully explained. As a result, the cost of these devices has put them into themainstream of modern energy producers. This was caused in part by advances in thetechnology, where PV conversion efficiencies have improved considerably.   French physicist Edmond Becquerel first described the photovoltaic (PV) effect in 1839,but it remained a curiosity of science for the next three quarters of a century. At only19, Becquerel found that certain materials would produce small amounts of electriccurrent when exposed to light. The effect was first studied in solids, such as selenium,by Heinrich Hertz in the 1870s. Soon afterward, selenium PV cells were convertinglight to electricity at 1% to 2% efficiency. As a result, selenium was quickly adopted inthe emerging field of photography for use in light-measuring devices.   Major steps toward commercializing PV were taken in the 1940s and early 1950s,when the Czochralski process was developed for producing highly pure crystallinesilicon. In 1954, scientists at Bell Laboratories depended on the Czochralski process todevelop the first crystalline silicon photovoltaic cell, which had an efficiency of 4%.   Solar Cells A solar cell is any device that directly converts the energy in light into electricalenergy through the process of photovoltaics. The development of solar cell technologybegins with the 1839 research of French physicist Antoine-César Becquerel. Becquerelobserved the photovoltaic effect while experimenting with a solid electrode in anelectrolyte solution when he saw a voltage develope when light fell upon the electrode.   What is often considered the first genuine solar cell was built around 1883 byCharles Fritts, who used junctions formed by coating selenium (a semiconductor)with an extremely thin layer of gold... These early solar cells, however, still hadenergy-conversion efficiencies of less than 1 percent. This impasse was finallyovercome with the development of the silicon solar cell by Russell Ohl in 1941.Thirteen years later three other American researchers, G.L. Pearson, DarylChapin, and Calvin Fuller, demonstrated a silicon solar cell capable of a 6-percentenergy-conversion efficiency when used in direct sunlight. - EncyclopediaBritannica   Solar Panels   A solar panel or battery converts the sun's energy to electricity. Gerald Pearson, CalvinFuller and Daryl Chapin invented the first sun energy battery in 1954. The inventorscreated an array of several strips of silicon (each about the size of a razorblade),placed them in sunlight, captured the free electrons and turned them into electricalcurrent. Bell Laboratories inNew Yorkannounced the prototype manufacture of a newsolar battery. Bell had funded the research. The first public service trial of the BellSolar Battery began with a telephone carrier system (Americus, Georgia) on October 41955.   Sun Energy Battery - In 1954, G.L. Pearson, C.S. Fuller, and D.M. Chapin invented thefirst solar panel battery.   SOLAR CELLS AND SOLAR PANELS - SOLAR NAVIGATOR WORL...http://www.solarnavigator.net/solar_cells.htm3 of 196/28/2013 12:19 PM    Solar panel array on Solar Navigator development model   Solar Panels in Space Extract: Nasa Jet Propulsion Laboratory ReporCrystalline silicon and gallium arsenideare typical choices of materials for solar panels for deep-space missions. Galliumarsenide crystals are grown especially for photovoltaic use, but silicon crystals areavailable in less-expensive standard ingots, which are produced mainly forconsumption in the microelectronics industry.   When exposed to direct sunlight at 1 AU, a 6-centimeter diameter silicon cell canproduce a current of about 0.5 ampere at 0.5 volt. Gallium arsenide is more efficient.Crystalline ingots are sliced into wafer-thin disks, polished to remove slicing damage,dopants are introduced into the wafers, and metallic conductors are deposited ontoeach surface: a thin grid on the sun-facing side and usually a flat sheet on the other.Spacecraft solar panels are constructed of these cells cut into appropriate shapes,protected from radiation and handling damage on the front surface by bonding on acover glass, and cemented onto a substrate (either a rigid panel or a flexible blanket),and electrical connections are made in series-parallel to determine total outputvoltage. The cement and the substrate must be thermally conductive, because in flightthe cells tend to heat up from absorbing infrared energy that is not converted toelectricity. Since cell heating reduces the operating efficiency it is desirable tominimize the heating. The substrate is supported on a deployable structuralframework. The resulting assemblies are called solar panels or solar arrays.   A solar panel is a collection of solar cells. Although each solar cell provides a relativelysmall amount of power, many solar cells spread over a large area can provide enoughpower to be useful. To get the most power, solar panels have to be pointed directly atthe Sun. Spacecraft are built so that the solar panels can be pivoted as the spacecraftmoves. Thus, they can always stay in the direct path of the light rays no matter howthe spacecraft is pointed. Spacecraft are usually designed with solar panels that canalways be pointed at the Sun, even as the rest of the body of the spacecraft movesaround, much as a tank turret can be aimed independently of where the tank is going.A tracking mechanism is often incorporated into the solar arrays to keep the arraypointed towards the sun.   Solar panels need to have a lot of surface area that can be pointed towards the Sun asthe spacecraft moves. More exposed surface area means more electricity can be SOLAR CELLS AND SOLAR PANELS - SOLAR NAVIGATOR WORL...http://www.solarnavigator.net/solar_cells.htm4 of 196/28/2013 12:19 PM
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