Solar panels are devices for capturing the energy in sunlight. The term solar panel can be applied to either solar hot water panels (usually used for providing domestic hot water) or solar photovoltaic panels (providing electricity).
Current DevelopmentRight now, countless corporations and institutions are developing ways to increase the practicality of solar power. While private companies conduct much of the research and development in this area, colleges and universities also work on solar-powered devices, especially solar-powered vehicles. Solar-powered cars have commonly appeared at many car and technology shows, and now solar boats are an interesting application of the technology. Colleges and Universities compete against each other for superiority in this field of technology. They meet in competitions such as the Solar Splash competition in North America, or the Frisian Nuon Solar Challenge in Europe. In 2005 the most important issue with Solar Panels is the cost has been coming down to about $3-4 a watt. Also grid tied systems are the largest growth area.
With incentives from States, power companies and in 2006 and 7 from the Federal government growth will continue to climb. Net-metering lets you get credit for any extra power you send back into the grid. Most is true net-metering with even prices for you to equal what you get charged, a few only give avoided cost at about 1/3 what they charge you. In Germany you get paid 8 times what the power company charges you. That large premium has made a huge demand in solar panels for that area. As manufacturers increase production the cost may drop in a year or more again. The price of silicon used for most panels is now being pressed and the price has increased. This has caused developers to start using other materials and thinner silicon to keep cost down. Renewable energy like solar PV gets less costly as we use and buy more.
Solar hot waterA solar water heater uses the sun's energy to heat a fluid, which is used to transfer the heat to a heat storage vessel. In the home, for example, sanitary hot water would be heated and stored in a hot water cylinder. Panels on the roof have an absorber plate to which fluid circulation tubes are attached. The absorber (usually coated with a dark selective coating) assures the conversion of the sun's radiation into heat, while fluid circulating through the tubes carries the heat away where it can be used or stored. The heated fluid is pumped to a heat exchanger (a coil in the storage vessel or an external heat exchanger) where it gives off its heat and is then circulated back to the panel to be reheated. This provides a simple and effective way of harnessing the sun's energy. Solar photovoltaics
Solar photovoltaic panels contain arrays of solar cells that convert light into electricity. They are called solar after the sun or "Sol" because the sun is the most powerful source of the light available for use. The solar cells are sometimes called photovoltaic cells, photovoltaic meaning literally "light-electricity". Solar cells or PV cells rely on the photovoltaic effect to absorb the energy of the sun and cause current to flow between two oppositely charged layers.
On a bright day, the sun delivers about 1 kW/m2 to the Earth's surface. At middle northern latitudes, taking the daylight cycle and weather conditions into account, on average 100 W/m2 in winter and 250 W/m2 in summer reach the ground. With a conversion efficiency of about 10 %, one can expect to obtain between 10 and 25 watts per square meter of solar cell.
Use of solar PVs
Together with a backup battery, they have become routine in certain low-power applications, such as powering buoys or devices in remote areas or simply where connection to the electricity mains would be impractical.
The relatively high cost of purchase and installation still prohibits their use in large-scale power generation. Solar PV panels currently make up a very small portion of the world's electricity production.
In experimental form they have even been used to power automobiles in races such as the World solar challenge across Australia. Many yachts and land-vehicles use them to charge on-board batteries away from grid power. Large-scale incentive programs, offering financial incentives like the ability to sell excess electricity back to the public grid, have greatly accelerated the pace of solar PV installations in Spain, Germany, Japan, the United States and other countries.
Even with these incentives, the start-up costs associated with solar electric panels currently push their likely 'pay-back' period into decades rather than years in applications where conventional "grid" power is readily available. As fossil fuel energy costs climb, production experience and economies of scale reduce prices, and technological advances increase the efficiency of solar cells, this may not be true in the relatively near future. Many installations at this time are motivated by tax incentives and green sensibilities.
The source of this article is Wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL
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