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Solar Energy

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Andrea Szyhowski

on 17 May 2010

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Transcript of Solar Energy

Renewable Energy :: Solar Where does my energy source come from? Solar energy comes from the Sun and is collected by Solar Collectors. How does it work? Silicon has four electrons in its outer shell. However, it has the capacity to hold eight. By sharing these four electrons with other silicon atoms and their four shell electrons, the capacity of eight is filled. When they combined with each other in this way, silicon atoms devlop a strong bond. This structure is known as pure, crystalline silicon. Of course, this pure silicon is a poor conductor of electricity, as there are no electrons free to move about. In other words, the silicon is better off with impurities. To create these impurities, silicon is combined with something else. When silicon combines with an element that has five electrons to share, such as phoshorus, a negative charge is created. Silicon can only take our four of the five electrons. This leaves one free electron looking for a spot. These additional electrons are known as free carriers; they carry an electrical current. On the other hand, when silicon is combined with an element that has three electrons a positive charge is created. Boron is a material which suits this purpose. When silicon and boron are combined, holes are created. These silicon combinations and their differing charges are used to make solar panels. As photons come down from the sunlight and strike the silicon, it shakes everything up. The free electron that was hanging onto the silicon/phosphorous combinationi is now forced to the outer ring. From here, it gets sucked up to the outer ring of the silicon/boron combination. This is how electricity is created. Has it been used successfully in the past? In the 1830s, the British astronomer John Herschel Famously used a solar thermal collector box (a device that absorbs sunlight to collect heat) to cook foor during an expedition to Africa. Solar Two during the early to mid-1990s, the facility is successfully demonstrating the ability to collect and store solar energy efficiently. Solar Two's success has opened the door for further development of this technology. What does it cost to get the energy? The cost of solar wind generators can be found for less than $800.00, while the cost of an entire solar energy system can be purchased for less than $12,000.00 Costs of solar energy will invole the purchase of solar energy panels which can generate 50-500 watts a piece, the solar energy generator for transforming solar energy into elecricity usable by the homeowners. Pengilly says his system would have cost him, $14,000 up front, and later, he'd get up to $10,000 of that back - over a few years - through tax incentives. The last four grand he'd recover - very slowly - by cutting his electric bill by about $25 a month Advantages Disadvantages Solar cells are long lasting sources of energy which can be used almost anywhere. Solar cells provide a cost effective solutions to energy problems in places where there is no mains electricity. Solar cells are also totally silent and non-polluting. As they have no moving parts they requier little maintenance and have a long lifetime. The main disadvantage of solar energy is the initial cost. Most types of solar cell require large areas of land to achieve average efficiency. Air pollution and weather can also have a large effect on the efficiency of the cells. The silicon used is also very expensive and the problem of nocturnal down times means solar cells can only ever generate during the daytime. Brought to you by: Andrea Szyhowski
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