Solar energy is sunshine
Source: National Renewable Energy Laboratory, U.S. Department of Energy
Source: National Renewable Energy Laboratory, U.S. Department of Energy
Source: United Nations Environment Programme (UNEP), NASA Surface meteorology and Solar Energy (SSE), 2008.
The amount of solar energy that the earth receives each day is many times greater than the total amount of energy consumed around the world. However, on the surface of the earth, solar energy is a variable and intermittent energy source. The amount of sunlight and the intensity of sunlight varies by location. Weather and climate conditions affect the availability of sunlight on a daily and seasonal basis. The type and size of a solar energy collection and conversion system determines how much of available solar energy can be converted into useful energy.
Solar thermal collectors
Low-temperature solar thermal collectors absorb the sun's heat energy to heat water or to heat air for heating in homes, offices, and other buildings.
Concentrating collectors
Concentrating solar energy technologies use mirrors to reflect and concentrate sunlight onto receivers that collect solar energy and convert it to heat. This thermal energy can then be used to produce heat or electricity with a steam turbine or a heat engine driving a generator.
Photovoltaic systems
Photovoltaic (PV) cells convert sunlight directly into electricity. PV systems can range from systems that provide tiny amounts of electricity for watches and calculators to systems that provide the amount of electricity used by hundreds of homes.
Hundreds of thousands of houses and buildings around the world have PV systems on their roofs. Many multi-megawatt PV power plants have also been built. Covering 4% of the world's desert areas with photovoltaics could supply the equivalent of all of the world's electricity. The Gobi Desert alone could supply almost all of the world's total electricity demand.