Every hour the sun throws more energy at Earth than would be needed to meet the world's energy needs for an entire year. Solar power is the technology used to harness the sun's energy and make it usable. Currently, the technology produces less than a tenth of 1% of the world's demand for energy.
sun based energy, radiation from the Sun equipped for creating heat, causing synthetic responses, or producing power. The aggregate sum of sun based energy occurrence on Earth is boundlessly in overabundance of the world's current and expected energy necessities. In the event that appropriately saddled, this profoundly diffused source can possibly fulfill all future energy needs. In the 21st century sun powered energy is supposed to turn out to be progressively alluring as an environmentally friendly power source due to its unlimited stock and its nonpolluting character, as a distinct difference to the limited petroleum products coal, oil, and flammable gas.
Many people are familiar with so-called photovoltaic cells, or solar panels, found on spacecraft, rooftops, and handheld calculators. Cells are made of semiconductor materials like those found in computer chips. When sunlight enters cells, it causes electrons to break away from their atoms. When electrons flow through the cell they generate electricity.
On a much larger scale, thermal power plants use various techniques to concentrate solar energy as a heat source. The heat is then used to heat water to drive a steam turbine which generates electricity in much the same way as nuclear power plants, supplying electricity for thousands of people.
One of these techniques uses a long series of U-shaped mirrors that focus sunlight onto a tube of oil flowing through the center. The hot oil then boils the water to generate electricity. Another of the techniques uses mobile mirrors to focus the sun's rays towards a collector tower where a receiver is located. Molten salt flowing through the receiver is heated to run a generator.
There are other solar technologies that are passive. For example, large windows on the sunny side of a building allow sunlight to penetrate heat-absorbing materials on the floor and walls. These surfaces release heat at night to keep the building warm. Similarly, absorber plates on the roof can heat the liquid in the pipes that supply hot water to a house.
Solar energy is praised as an inexhaustible fuel source free of pollution and noise. The technology is also versatile. For example, solar cells generate power for remote places like Earth-orbiting satellites and cabins in the Rocky Mountains just as easily as they power downtown buildings and futuristic cars.
However, solar energy does not work at night without a storage device such as a battery and if there are clouds this technology is not very reliable during the day. Solar technology is also very expensive and requires a lot of land to collect solar energy at rates useful to many people.
Despite the drawbacks, solar energy use has increased by 20% a year for the past 15 years thanks to rapidly declining prices and efficiency gains. Japan , Germany and the United States are the main markets for solar cells. With tax incentives, solar electricity can often pay for itself in five to ten years.
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