Solar Energy

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Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used. Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection,daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels. Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.

Solar Energy Uses We have always used solar energy as far back as humans have existed on this planet. We know today, that there are multiple uses of solar energy. We use the solar energy every day in many different ways. When we hang laundry outside to dry in the sun, we are using the solar heat to do work, drying our clothes. Plants use the solar light to make food. Animals eat plants for food. And as we learned, decaying plants hundreds of millions of years ago produced the coal, oil and natural gas that we use today.

very often there is confusion about the various methods used to harness solar energy. Energy from the sun can be categorized in two ways: (1) in the form of heat (or thermal energy), and (2) in the form of light energy. Solar thermal technologies uses the solar heat energy to heat substances (such as water or air) for applications such as space heating, pool heating and water heating for homes and businesses. There are a variety of products on the market that uses solar thermal energy. Often the products used for this application are called solar thermal collectors and can be mounted on the roof of a building or in some other sunny location. The solar heat can also be used to produce electricity on a large utilityscale by converting the solar energy into mechanical energy. So, fossil fuels are actually solar energy stored millions and millions of years ago. Indirectly, the sun or other are responsible for all our energy. Even nuclear energy comes from a star because the uranium atoms used in nuclear energy were created in the fury of a nova - a star exploding. Let's look at ways in which we can use the solar energy.

Solar water heating (SWH) systems comprise several innovations and many mature renewable energy (or SHW Solar Hot Water) technologies which have been accepted in most countries for many years. SWH has been widely used in Greece, Turkey, Israel, Australia, Japan, Austria and China.

In a "close-coupled" SWH system the storage tank is horizontally mounted immediately above the solar collectors on the roof. No pumping is required as the hot water naturally rises into the tank through thermo siphon flow. In a "pump-circulated" system the storage tank is ground or floor mounted and is below the level of the collectors; a circulating pump moves water or heat transfer fluid between the tank and the collectors. SWH systems are designed to deliver the optimum amount of hot water for most of the year. However, in winter there sometimes may not be sufficient solar heat gain to deliver sufficient hot water. In this case a gas or electric booster is normally used to heat the water. The Advantages of Solar Water Heating Systems With the rising cost of energy and the prospect of shortages in the future, the idea of harnessing the power of the sun as a renewable energy source is gaining in popularity around the world. According to Solar Direct, there are more than 300,000 solar water heating units installed in the U.S., and the number is growing as people realize the many advantages of solar heating. Cost efficient , available energy ,

solar Thermal Electricity

Solar energy can also be used to make electricity. Some solar power plants use a highly curved mirror called a parabolic trough to focus solar light on a pipe running down a central point above the curve of the mirror. The mirror focuses the solar light to strike the pipe, and it gets so hot that it can boil water into steam. That steam can then be used to turn a turbine to make electricity. In California's Mojave desert, there are huge rows of solar mirrors arranged in what's called "solar thermal power plants" that use this idea to make solar electricity from solar energy for more than 350,000 homes. The problem with solar energy is that it works only when the sun is shining. So, on cloudy days and at night, the power plants can't create energy. Some solar plants, are a "hybrid" technology. During the daytime they use the solar energy. At night and on cloudy days they burn natural gas to boil the water so they can continue to make electricity. Another form of solar power plants to make electricity is called a Central Tower Power Plant, e.g. the Solar Two Project. Solar light is reflected off 1,800 mirrors circling the tall tower. The mirrors are called heliostats and move and turn to face the sun all day long to use solar energy. The solar light is reflected back to the top of the tower in the center of the circle where a fluid is turned very hot by the sun's rays. That fluid can be used to boil water to make steam to turn a turbine and a generator.This experimental power plant is called Solar II. It was re-built in California's desert using newer technologies than when it was first built in the early 1980s. Solar II will use the solar light to change heat into mechanical energy in the turbine.The power plant will make enough electricity from solar energy to power about 10,000 homes. Scientists say larger central tower power plants can make electricity for 100,000 to 200,000 homes.

Solar Panels Solar power is probably the cleanest, most viable form of renewable energy available today. Solar panels convert light into electricity using arrays of solar cells (also called photovoltaic cells). This electricity can then be used to power appliances in your home, or if you include a grid tie system you can actually sell unused electricity back to the grid.

Photovoltaic tiles take the place of ordinary roof tiles and can be perfectly blended to fit the look of the outside of your house. Solar Energy has several advantages to the evironment since it is clean, renewable (unlike gas, oil and coal) and sustainable. Governments are beginning to offer grants to assist in paying for photovoltaic roof tiles, which should help making solar power more widely available in the near future.

Solar cells

Solar cells are in fact large area semiconductor diodes. Due to photovoltaic effect energy of light (energy of photons) converts into electrical current. At p-n junction, an electric field is built up which leads to the separation of the charge carriers (electrons and holes). At incidence of photon stream onto semiconductor material the electrons are released, if the energy of photons is sufficient. Contact to a solar cell is realised due to metal contacts. If the circuit is closed, meaning an electrical load is connected, then direct current flows. The energy of photons comes in "packages" which are called quants. The energy of each quantum depends on the wavelength of the visible light or electromagnetic waves. The electrons are released, however, the electric current flows only if the energy of each quantum is greater than WL - WV (boundaries of valence and conductive bands). The relation between frequency and incident photon energy is as follows:

Solar car. A solar car is a solar vehicle used for land transport. Solar cars combine technology typically used in the aerospace, bicycle, alternative energy and automotive industries. The design of a solar vehicle is severely limited by the amount of energy input into the car. Most solar cars have been built for the purpose ofsolar car races. Exceptions include solar-powered cars and utility vehicles. Solar cars are often fitted with gauges as seen in conventional cars. In order to keep the car running smoothly, the driver must keep an eye on these gauges to spot possible problems. Cars without gauges almost always feature wireless telemetry, which allows the driver's team to monitor the car's energy consumption, solar energy capture and other parameters and free the driver to concentrate on driving. Solar cars depend on PV cells to convert sunlight into electricity. In fact, 51% of sunlight actually enters the Earth's atmosphere.[1] Unlike solar thermal energy which converts solar energy to heat for either household purposes, industrial purposes or to be converted to electricity, PV cells directly convert sunlight into electricity.[2] When sunlight (photons) strike PV cells, they excite electrons and allow them to flow, creating an electrical current. PV cells are made of semiconductor materials such as silicon and alloys of indium, gallium and nitrogen. Silicon is the most common material used and has an efficiency rate of 15-20%. Of late, several consulting companies, such as Phoenix Snider Power, have started offering technical and financial services to institutes and teams developing solar cars worldwide

Solar Power-Advantages and Disadvantages March 14, 2008 There are many advantages worth considering when it comes to solar energy and everything that it offers. There are many advantages that solar energy has over oil energy. Not only does solar energy benefit your pocketbook, but it also benefits the environment as well. However, there are two sides to everything, and there is a list of solar power disadvantages to accompany the list of advantages. Advantage: Solar energy is a completely renewable resource. This means that even when we cannot make use of the sun¶s power because of nighttime or cloudy and stormy days, we can always rely on the sun showing up the very next day as a constant and consistent power source. Disadvantage: The Solar Cells and Solar Panels that are needed to harness solar energy tend to be very expensive when you first purchase them. Advantage: Oil, which is what most people currently use to power their homes, is not a renewable resource. This means that as soon as the oil is gone, it is gone forever and we will no longer have power or energy. Disadvantage: Solar power cannot be harnessed during a storm, on a cloudy day or at night. This limits how much power can be saved for future days. Some days you may still need to rely on oil to power your home. Advantage: Solar cells make absolutely no noise at all. They do not make a single peep while extracting useful energy from the sun. On the other hand, the giant machines utilized for pumping oil are extremely noisy and therefore very impractical. Advantage: Solar energy creates absolutely no pollution. This is perhaps the most important advantage that makes solar energy so much more practical than oil. Oil burning releases harmful greenhouses gases, carcinogens and carbon dioxide into our precious air. Advantage: Very little maintenance is required to keep solar cells running. There are no moving parts in a solar cell, which makes it impossible to really hurt them. Solar cells tend to last a good long time with only an annual cleaning to worry about. Advantage: Solar panels and solar lighting may seem quite expensive when you first purchase it, but in the long run you will find yourself saving quite a great deal of money. After all, it does not cost anything to harness the power of the sun. Unfortunately, paying for oil is an expensive prospect and the cost is still rising consistently. Why pay for expensive energy when you can harness it freely? Advantage: Solar powered panels and products are typically extremely easy to install. Wires, cords and power sources are not needed at all, making this an easy prospect to employ. Advantage: Solar power technology is improving consistently over time, as people begin to understand all of the benefits offered by this incredible technology. As our oil reserves decline, it is important for us to turn to alternative sources for energy.

Solar Power Benefits to The Environment Solar power is green and benefits the environment a number of ways, some we have already mentioned like it is renewable and eco friendly. Obviously, the two main advantages over fossil fuels are that it doesn¶t produce green house gases like CO2 and there are no potential disasters that will harm the environment which tends to come from either mining, drilling or digging ± or transporting from one place to another. Solar Power Better Than Other Forms of Energy Solar power is better than fossil fuels because you do not have the problems of transporting coal, oil and gas across vast distances which not only is the transportation system polluting the environment, but you are constantly running the risk of environmental disasters like oil spillages or exploding pipelines. You do not have to have large storage facilities and there are no dangerous or expensive environmental waste disposal problems. Furthermore, it is renewable! It is a highly developed market compared to wind turbines and have lots of products available for residential homes with many more in the design phase. If you want to build your own solar panels, there are kits you can buy which make it easy for the DIY¶er. The kit will specify the output (watt), include a DC to AC inverter and provide tips and advice.

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