What Devices Are Used to Convert Solar Energy to Heat?

Solar energy, or the sun's energy, can provide power to hot water heaters and wall heaters through a conversion system that contains numerous devices. Unlike fossil fuel energy, solar power is clean, abundant and sustainable. Currently, solar power supplies only 1 percent of America's energy needs, in part because it is expensive: Water heaters used in the conversion system, for example, can cost from $1,000 to $3,500, and wall heaters, from $800 to more than $4,000. In addition, auxiliary systems are needed. A well-designed, active solar system includes such devices and equipment as collectors, storage tanks, pumps and thermostats.

Active and Passive Systems

• Glass windows or walls facing south are part of a passive solar system.

  The two types of solar power systems are active and passive. An active solar power system uses a mechanical system and its devices to convert sunlight into heat. A passive system, however, gets sunlight and heat through the building's position in relation to the sun. Windows and glass walls, for example, are positioned to the south and away from the shady trees.

Collectors

• Collectors are usually positioned at a 30-degree angle relative to the ground.

  A solar collector generally sits on top of the roof in a sunny location. It is usually a flat, boxlike unit covered with dark, absorbent glass, which contains plates that absorb sunlight and convert it into heat. A heat transfer fluid then circulates the heat from the collector through the building's solar system. The collectors should face south and have full sun from 9 a.m. to 3 p.m.

Storage Tanks

• The solar system includes two storage tanks. A smaller one stores the heat transfer liquid, which flows to the solar collector and eventually heats the water stored in a second, larger tank. Once heated, the water can flow through pipes to the home's faucets and shower heads and into the heating system. The large storage tank should hold 20 to 30 gallons of hot water for each person living in a solar house.

Piping, Pumps and Auxiliary Systems

• The solar heating system includes numerous other mechanical devises: thermostats, pumps, blowers and ducts. A thermostat, for example, is positioned in the collector; when it registers a certain temperature, a pump begins to pump the heat transfer fluid through pipes to the collector. Although a well-designed system can provide most of a home's heating and hot water needs, it usually cannot provide all of it. Thus, an auxiliary system, such as a furnace or a wood-burning stove, may be required for cloudy days or for colder climates.