The sun is the main source of energy for all living beings on the Earth. Plants store solar energy by photosynthesis in the form of chemical energy which in other words is food. This stored energy in plants is used by all of us in the form of food.
Scientists have been able to make solar cookers, solar water heaters and solar cells which work on solar energy. Solar cookers and solar heaters are being used to cook food and for supplying hot water in hospitals, hostels and hotels. Solar cells are being used to generate electricity on a small scale for domestic purposes in some remote villages. Solar batteries are used for space flights. Solar energy is also being used to obtain distilled water for use in hospitals, laboratories and batteries of automobiles.
The supply of solar energy represents an inexhaustible resource which is not affected by human activities. The potential lifetime of the Sun is in hundreds of millions of years, barring cosmic accidents. Sun has the capability of fulfilling all energy requirements of human beings. That energy supply, however, depends on the condition of the atmosphere, which can be affected by human activities.
It is the biggest form of renewable source of energy, much of which remains unused. A very small fraction of the total solar energy radiated from the sun reaches the living organisms. Solar radiation can either be converted into thermal energy or electrical energy.
The two main devices concentrating collectors and flat-plate collectors are utilized to gather solar energy and transform it to thermal energy. Solar energy is converted into thermal energy with the help of solar collectors and receivers.
Large arrays consisting of thousands of these semi-conductor cells can function as central power stations. Other systems, which are still under development, are designed to concentrate solar radiation and not only to generate electric power but also to produce high- temperature process heat for various applications. Another approach involves the user of flat-plate solar collectors to provide space heating for commercial and residential buildings.
Solar energy can be used for heating water during winters.
It can be used for cooking purpose by using solar cookers. It can be used for making solar furnace which has become an important tool in high temperature research.
Solar radiation may be converted directly into electricity by photovoltaic cells or photocells, which provide electricity for vehicles and streetlights.