/ ˈsoʊlər ˈenərdʒi /
Energy from the sun that is converted into thermal or electrical energy; SYN. solar power.
Energy derived from the Sun’s radiation. The amount of energy falling on just 1 sq km/0.3861 sq mi is about 4,000 megawatts, enough to heat and light a small town. In one second the Sun gives off 13 million times more energy than all the electricity used in the US in one year. Solar heaters have industrial or domestic uses. They usually consist of a black (heat-absorbing) panel containing pipes through which air or water, heated by the Sun, is circulated, either by thermal convection or by a pump.
Solar energy may also be harnessed indirectly using solar cells (photovoltaic cells) made of panels of semiconductor material (usually silicon), which generate electricity when illuminated by sunlight. Although it is difficult to generate a high output from solar energy compared to sources such as nuclear or fossil fuels, it is a major nonpolluting and renewable energy source used as far north as Scandinavia as well as in the SW US and in Mediterranean countries.
A solar furnace, such as that built in 1970 at Odeillo in the French Pyrénées, has thousands of mirrors to focus the Sun's rays; it produces uncontaminated intensive heat (up to 3,000şC/5,4000şF) for industrial and scientific or experimental purposes. The world's first solar power station connected to a national grid opened in 1991 at Adrano in Sicily. Scores of giant mirrors move to follow the Sun throughout the day, focusing the rays into a boiler. Steam from the boiler drives a conventional turbine. The plant generates up to 1 megawatt. A similar system, called Solar 1, has been built in the Mohave desert near Daggett, California, US. It consists of 1,818 computer-controlled mirrors arranged in circles around a central boiler tower 91 m/300 ft high. Advanced schemes have been proposed that would use giant solar reflectors in space to harness solar energy and beam it down to Earth in the form of microwaves. Despite their low running costs, their high installation cost and low power output have meant that so
lar cells have found few applications outside space probes and artificial satellites. Solar heating is, however, widely used for domestic purposes in many parts of the world, and is an important renewable source of energy. .