We know that the sun is the ultimate source of energy. Sun has produced energy for billion of years and is likely to continue doing the same for a similar length of time. It provides energy in the form of heat and light. It provides food energy to all forms of life and is also responsible for wind energy and the energy of fossil fuels.
Solar energy can be harnessed in two ways. Solar energy can be harnessed as thermal energy also known as heat energy. Solar energy can be harnessed in the form of light energy.
In both cases, solar energy can be put to various uses. Solar energy accounts for most of the renewable energy available on the earth. However, only a small fraction of solar energy is being put to use.
About 30% of the solar radiations received by the earth are reflected back into the atmosphere causing a rise in the temperature. The air heated by the solar energy rises in the form of water vapors. At high altitudes where temperature is low, the water vapor condenses and falls as rain on the earth to complete the water cycle. The solar energy is converted to chemical energy which produces food in plants by the process of photosynthesis. The solar energy when converted to chemical energy also produces biomass from which fossil fuels are derived.
The unlimited solar energy from the sun is freely available on the earth. It can be tapped in a cost effective manner to give the maximum output.