Solar Thermal systems collect the heat from sunlight to produce hot water, heat, or electric power. Solar Thermal differs from Passive Solar in that a mechanical device distributes the heated water or air throughout the building.
Solar Power water heating systems are the most popular form of solar energy. Low-temperature systems are installed on roofs which are preferably south facing and the system is then connected to the hot water system. Medium temperature systems heat either air or liquid as a heating conductor and are used to provide space, water, and process heating. These usually consist of flat-plate collectors: large, flat boxes that are dark inside, with one or more glass covers.