The sun is constantly bathing our planet with a free energy supply. Our simplest and oldest use of solar energy is passive solar system, using natural materials to simply gather and hold heat. For example, thick-walled stone that slowly collect heat during the day and gradually release heat at night. Whereas, active solar system, solar energy is converted into heat, but the heat must be transferred from the collection area to the place of use. Both passive and active solar systems, solar energy canbe used under heat energy form