Solar energy

Solar energy is based on the sun's energy and light to provide heat, light, electricity, and cooling, for houses, shops and small industries. 

The relative stability of Earth’s temperature suggests a near balance between planetary input and output of energy. The input is almost entirely solar radiation, which amounts to 173,000 TW.

                                                 
There are various technical methods that have been developed to take advantage of solar energy. Those are as follows 

  

Photovoltaic Systems

Producing electricity directly from sunlight. Solar cells convert sunlight directly into electricity.When sunlight is absorbed by these cell materials, the solar energy penetrate electrons loose from their atoms. This process of converting light (photons) to electricity (voltage) is called the photovoltaic (PV) effect.

                  

Most solar cells are designed for concentrated sunlight. These cells are built into concentrating collectors that use a lens to focus the sunlight onto the cells. As the lenses must be pointed at the sun, the use of concentrating collectors is limited to the sunniest parts of the country. Some concentrating collectors are designed by using tracking devices. The performance of a solar cell is measured in terms of its efficiency.

 Solar Hot Water

Heating water with solar energy.

 Solar Electricity

By using the sun's heat to produce electricity. Now a days most of the power plants use coal, gas, oil. These fuels uses as a heat source to boiler. But is really expensive. Moreover Fossil fuels are not unlimited.
So now  a days scientists are developing solar power systems, which is used as a heat source. There are three main types solar power systems.
parabolic-trough
dish/engine
power tower.