Solar Renewable Energy
Posted on January 5, 2010
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The sun is like an enormous fusion reactor that has been burning over 4 billion years providing earth with enough energy in one minute to supply our energy needs for one year. In one day, it provides more energy than our current population would consume in 27 years. In three days it provides the amount of energy stored in all fossil energy sources.
Solar energy may have had great potential, but it was left on the backburner whenever fossil fuels were more affordable and available. Only in the last few decades when growing energy demands, increasing environmental problems and declining fossil fuel resources made us look to alternative energy options have we focused our attention on truly exploiting this tremendous resource. For instance, the US Department of Energy funded the installation and testing of over 3,000 PV systems during the 1973-1974 oil embargo. By the late 1970s, energy companies and government agencies had invested in the PV industry, and a tremendous acceleration in module development took place. Solar energy improvements were again sought during the Gulf War in the 1990s.
We still use solar power in the same two forms today, thermal and photovoltaic. The first concentrates sunlight, converts it into heat, and applies it to a steam generator or engine to be converted into electricity in order to warm buildings, heat water, generate electricity, dry crops or destroy dangerous waste. Electricity is generated when the heated fluid drives turbines or other machinery. The second form of solar power produces electricity directly without moving parts. Today’s photovoltaic system is composed of cells made of silicon, the second most abundant element in the earth’s crust. Power is produced when sunlight strikes the semiconductor material and creates an electric current. The smallest unit of the system is a cell. Cells wired together form a module, and modules wired together form a panel. A group of panels is called an array, and several arrays form an array field.
There are several advantages of photovoltaic solar power that make it one of the most promising renewable energy sources in the world. It is non-polluting, has no moving parts that could break down, requires little maintenance and no supervision, and has a life of 20-30 years with low running costs. It is especially unique because no large-scale installation is required. Remote areas can easily produce their own supply of electricity by constructing as small or as large of a system as needed. Solar power generators are simply distributed to homes, schools, or businesses, where their assembly requires no extra development or land area and their function is safe and quiet. As communities grow, more solar energy capacity can be added, thereby allowing power generation to keep in step with growing needs without having to overbuild generation capacity as is often the case with conventional large scale power systems. Compare those characteristics to those of coal, oil, gas, or nuclear power, and the choice is easy. Solar energy technologies offer a clean, renewable and domestic energy source. Photovoltaic power even has advantages over wind power, hydropower, and solar thermal power. The latter three require turbines with moving parts that are noisy and require maintenance.
Solar energy is most sought today in developing countries, the fastest growing segment of the photovoltaics market. People go without electricity as the sun beats down on the land, making solar power the obvious energy choice. Governments are finding its modular, decentralized character ideal for filling the electric needs of the thousands of remote villages in their countries. It is much more practical than the extension of expensive power lines into remote areas, where people do not have the money to pay for conventional electricity.
India is becoming one of the world’s main producers of PV modules, with plans to power 100,000 villages and install solar-powered telephones in its 500,000 villages. By 2000, Mexico plans to have electrified 60,000 villages with solar power. Zaire ‘s Hospital Bulape serves 50,000 outpatients per year and is run completely on solar power, from air conditioning to x-ray equipment. And in Moroccan bazaars, carpets, tin ware, and solar panels lie side by side for sale. Probably the most outstanding example of a country’s commitment to solar power is in Israel . In 1992, over half of all households (700,000) heated their water with solar energy systems. And there are 50,000 new installations every year.
Household energy supply is but one use of solar power. There are actually four broad categories that can be identified for solar energy use: industrial, rural habitation, grid-connected, and consumer/indoor. Industrial uses represent the largest applications of solar power in the past 30 years. Telecommunications, oil companies, and highway safety equipment all rely on solar power for dependable, constant power far from any power lines. Roadside call boxes and lighted highway signs rely on the sun’s energy in order to provide reliable services without buried cable connections or diesel generators. Navigational systems such as marine buoys and other unmanned installations in harsh remote areas are also ideal applications for solar power because the load demands are well known and the requirements for reliable power are the highest. Rural habitation includes cabins, homes, villages, clinics, schools, farms, as well as individually powered lights and small appliances. Grid-connected systems pair solar power with an existing grid network in order to supply a commercial site with enough energy to meet a high demand, or to supplement a family’s household supply. Consumer/indoor uses of PV cells include watches and calculators; PV modules power computers and radios.
There are only two primary disadvantages to using solar power: amount of sunlight and cost of equipment. The amount of sunlight a location receives varies greatly depending on geographical location, time of day, season and clouds. The southwestern United States is one of the world’s best areas for sunlight . Globally, other areas receiving very high solar intensities include developing nations in Asia, Africa and Latin America.
The best way of lowering the cost of solar energy is to improve the cell’s efficiency, according to Larry Kazmerski, Director of the DOE’s National Center for Photovoltaics – “As the scientists and researchers at the NCPV push the envelope of solar-cell efficiency, we can begin to visualize the day when energy from the sun will be generating a significant portion of the country’s electric power demand.” “Any improvements and subsequent cost cuts will also be vital to space applications.”
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