We have proved the commercial profit of sun power in the tropics and have more particularly proved that after our stores of oil and coal are exhausted the human race can receive unlimited power from the rays of the sun.
— Frank Shuman, New York Times, July 2, 1916
The Sun has been converting Hydrogen into Helium since 4.6 billion years through a process called nuclear fission. It will continue this process for another 5 million years until all of the Hydrogen is consumed. That’s not it! After consuming all the Hydrogen, it will burn Helium for another 130 million year before becoming a white dwarf. That is why the Sun is practically inexhaustible source of energy.
Solar energy has been used since prehistoric times, but in a most primitive manner. Before 1970, some research and development was carried out in a few countries to exploit solar energy more efficiently, but most of this work remained mainly academic. After the dramatic rise in oil prices in the 1970s, several countries began to formulate extensive research and development programs to exploit solar energy.
Solar energy is pretty clean and benign source of energy. Advancement in technology has made it possible to harness this energy and convert it into electricity. The Earth receives 174,000 terawatts (TW) of incoming solar radiation (insolation) at the upper atmosphere. Most people around the world live in areas with insolation levels of 150 to 300 watt per square meter or 3.5 to 7.0 kWh/m2per day.
Solar Energy Applications