Solar energy originates from the Sun. It is created by nuclear fusion reactions that occur in the Sun's core. It can be used to generate electricity, provide hot water, and to heat, cool, and light buildings. It is the most important and vital factor of life, because any substantial change in its radiation power would alter or end life on Earth.
The Earth naturally collects solar energy in oceans, plant life, and in the atmosphere. Humans can use this to influence technology. A direct way of obtaining solar energy is by two different kinds of artificial collectors. These are called flat plate collectors and concentrating collectors. The former are thin boxes with a see-through cover, which are placed of the top of roofs and facing the sun. These are used for water and space heating. Concentrating collectors are more expensive and complicated; therefore, they are more beneficial for uses such as air conditioning and central power generation. The temperatures they can acquire are higher than that of flat plate collectors. .
Solar energy falls on buildings and is used to heat them without special devices. This passive way of heating a building is maintained by the construction of the buildings (large windows and absorbing materials on the outside). This can reduce an energy bill up to 50 percent. For cooling purposes, an absorption air conditioner or refrigerator uses a solar collector that stimulates the cooling process. This is due to the fact that evaporation requires heat energy. .
For solar energy to be converted into electricity, photovoltaics are made from silicon or other semiconductor resources. The solar energy jars electrons loose from their atoms, letting the electrons flow through the material to produce electricity. These PV cells are typically grouped into modules of approximately 40 cells. This can be used to generate electricity in a building or a power plant, and to operate solar batteries.