Solar Heating can be used as space or water heating which uses the heat energy from the sun’s radiation. There are two different types: passive solar heating (or Passive Solar Design), where the building itself, or parts of it, such as a sun room, are used as a collector, and active solar heating.
In active solar heating, the heat absorbed by the Solar Collector can be used for heating potable water and for space or Floor Heating. When it’s not immediately needed, the energy, in the form of hot water, must be stored in a tank.
The heat stored there can then be used at a later time. The ‘power plant’ of a Solar Heating System is the collector. In the hot water storage tank (Heat Storage Device) are two heat exchangers. Through one of the heat exchangers hot heat-transfer fluid, which raises the temperature of the potable water, flows from the collector. The second Heat Exchanger is connected to the conventional boiler so during winter months the potable water can still be adequately heated. Solar heating systems used as Backup Heating systems require a special type of water tank which separates potable water from the heating water (i.e. tank-in-tank-system). An electronic Controller, or Regulator, regulates the circulation between the collector and water tank as well as between the water tank and the radiators or warm water faucets.
In a private household, however, solar heating systems offer backup heating during spring or fall. During these times, conventional heating systems can be used up to 50% less and therefore contribute to the reduction of CO2 emissions.
The effective and economical use of Solar Energy for Heating purposes is currently being demonstrated in Solar Settlements. Such large systems for local heating (for example in Neckarsulm, Friedrichshafen, and Hamburg (all in Germany)) can be used quite well in conjunction with a Block-Type Thermal Power Station (BTTP) as the main sources for a community’s energy supply.