Solar energy (Solar Energy), generally refers to the Sun's radiant energy, in modern times usually used for power generation or energy for water heaters. Since the formation of the Earth, living mainly in the heat and light of the Sun live, and since ancient times, humans know how to Sun-dried items and as a way to preserve food, such as salt and drying salt fish, and so on. In the case of decreasing fossil fuel, solar energy has become an important part of human energy use, and continue to develop. By using the passive use of solar energy (solar thermal) and photoelectric conversion in two ways, solar hot water project is a new kind of renewable energy. Solar power in a broad sense, including the Earth's wind energy, chemical energy, water, etc.
Solar energy is by an internal hydrogen atoms of hydrogen-helium fusion can release a tremendous amount of nuclear energy, radiant energy from the Sun. Material in building solar hot water project system for timber-built solar hot water project system in the human energy needed and most of them either directly or indirectly from the Sun. Plants release oxygen and absorb carbon dioxide through photosynthesis and convert solar energy into chemical energy stored in plant down. Coal, oil, natural gas and other fossil fuels is composed of ancient plants and animals buried in the ground after a long evolution of primary energy for the formation of the geological time scale. Earth itself, there is more energy usually associated with the thermal energy in the Earth's energy and energy related to nuclear reactions.