Solar Power

Solar Energy Solar energy is the energy that is coming from the sun. It can be collected by human through photovoltaics and heat engines.  Solar Power, along with wind, hydroelectric, wave, biomass account for most of the renewable energy source available to use.

 Photovoltaics. (8.4.1.2) Photovoltaics is the direct conversion of light into electricity at the atomic level. A photovoltaic cell(PV) is a device that converts sun light into direct current through photoelectric effect.  Individual PV cells are electricity-producing devices that are made of semiconductor materials.    The photoelectric effect is first noted by French physicist Edmund Bequerel in 1839.    The first PV cell was constructed by Charles Fritts in 1880.  The first major usage of PV cell is on the Vanguard I satellite in 1958.  The increase in oil price, and the increase in production brought the price of photovoltaic cell down. 

Continue In general, photovoltaic modules and arrays produce DC electricity.  The most commonly used photovoltaic device is in a single junction or interface. A multijunction device is a stack of single junction cells together serving as the collector. Research are being done on Gallium Arsenide, Amorphous Silicon, and Copper Indium Diselenide. PV cells come in different shapes and sizes.  It can be the size of a stape, or several inches.  Depending on the level of need, the PV cells can be put together to form a field or a single module for residential usage.  The photoelectric effect causes some materials to absorb light photons and convert them into electrons. 

Solar Heating Panel (8.4.12) Concentrating Solar Power or (CSP) is another way of collecting energy from sun. Concentrating Solar Power system is made up of lenses, mirrors, and tracking systems focusing a large amount of sunlight into a smaller beam. The concentrated light heat up a working fluid and is then used as the heat source for power generation or energy storage. The most developed methods for CSP are solar trough, parabolic dish, and solar power tower. Unlike photovoltaics, CSP can be used at a larger scale and is more energy efficient. Unlike PV which converts solar ray directly into electricity, CSP system use heat to generate a motor in order to create energy.

Continue In the solar power tower unit, the working fluid is heated up to 500-1000 °C. Then it is used for power generation or energy storage. Ultimately, a solar power tower offer more energy efficiency and can store more energy than a solar trough system. Each method of concentrating solar power convert different amount of energy. In a solar trough, the working fluid is heated up to 150-350 °C, then it is used as the hearing source to a power generation unit. In the parabolic system, the working fluid is heated up to 250-700 °C. The heat is then used by a stirling engine to generate electricity.

Seasonal and Regional Effect. (8.4.13) Solar Power, unlike hydroelectric, wave it can not be controlled by human. Thus the regional and seasonal effect on solar power is greater than the other renewable resources. First,a solar power should be station at a well lit area. For example the desert area or high ground where the intensity of the sunlight is highest. Second, solar power can be collected all year round, it will gather more sun light during the summer due to more day light. Areas such as the Saharan desert, Nevada, California, Australia etc are good places to build a solar power system because they are the well lit area on earth.   

Photovoltaics (8.4.14) Example of a Photovoltaic module, Another example would be the building 678 PV Rooftop System at Naval Air Station North Island, San Diego, CA.  Where they installed a PV system generating 30.54 MW of power in 2000, with 198 panels each producing 116 watts. 

Concentrating Solar Power (8.4.14) An Example of CSP is the SEGS plant in California, where the plant has the installed capability of 354 MW of power, and the general gross output is 75 MW of power, the station receive an average of 340 days of sun light and the direct normal radiation is 7.44 kwh/m²/day, (310 W/m²).  

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Continue "Map1-global-solar-power." Solar power can be a practical power source when using advanced photovoltaic equipment. Advanced Energy Group. 02 Feb. 2009 <http://www.solar4power.com/map1-global-solar-power.html>. SLV Dweller. 02 Feb. 2009 <http://www.slvdweller.com/uploads/SkyFuel_diagram_jp70.jpg>. "Solar Energy Technologies Program: Concentrating Solar Power." EERE: EERE Server Maintenance. 15 Sept. 2005. U.S department of Energy. 02 Feb. 2009 <http://www1.eere.energy.gov/solar/csp.html>. "Solar Energy Technologies Program: PV Physics." EERE: EERE Server Maintenance. 28 Dec. 2005. U.S department of Energy. 02 Feb. 2009 <http://www1.eere.energy.gov/solar/pv_physics.html>.

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