This book entitled Application of Solar Energy is intended to provide a focus in various facets, such as household, commercial and industrial applications of solar energy. Solar energy is radiant light and heat from the Sun harnessed using a range of ever-evolving technologies such as solar heating, photovoltaic, solar thermal energy, solar architecture and artificial photosynthesis. This energy moves from sun and reaches the earth where human collects it through solar collectors and convert it into any desirable form of energy. According to an assumption this renewable source of energy is powerful enough to replace the need of electricity that we get from 650 barrels of oil per year. In conventional power plants nonrenewable energy sources are used to boil water and form stream so that turbines can rotate and water to produce electricity. Use of solar energy is increasing in homes as well. Residential appliances can easily use electricity generated through solar power. Besides this solar energy is running solar heater to supply hot water in homes. On roofs of different buildings we can find glass PV modules or any other kind of solar panel. These panels are used there to supply electricity to different offices or other parts of building in a reliable manner. At many places solar energy is used for ventilation purposes. It helps in running bath fans, floor fans, and ceiling fans in buildings. Solar power not just helps in improving ventilation system at your homes but with that it can also help in circulating water in any building. Solar lights are also known as day lighting, and work with help of solar power. It will increase energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating global warming, and keep fossil fuel prices lower than otherwise. These advantages are global.