What Is Active Solar Energy
Active Solar Domestic Water Heating
Providing hot water for washing, showering and other uses in a home is usually produced by an electric, oil or gas water heater. Water is heated in a tank by flame, or in the case of electric water heaters, an electrical element is immersed in the water. A typical active thermal solar hot water system consists of collectors mounted on a home's south-facing roof. The collectors are black to absorb the most heat from the sun's rays, similar to a greenhouse effect. Pipes inside the collectors are filled with a heat transfer medium, usually a mixture of water and antifreeze. Hot air in the collector box is transferred to the fluid in the pipes. A pump circulates the fluid down through the water tank to heat the tank's water. The fluid does not come in contact with the water used by the homeowners.
Space Heating
In many large buildings and some industrial situations, fresh air is drawn in from outdoors for ventilation. To reduce heating costs, the air can be preheated before being distributed throughout the building. In this type of installation, air is heated by the sun hitting a darkly colored, perforated aluminum sheet and drawn in by a fan. The building's conventional heating system has to do less work to make up the temperature difference between the incoming air and room temperature air.
Swimming Pool Heating
Changing the temperature of water requires a lot of energy, and therefore can be expensive to heat. In regions where the summer season is short, pool owners can extend the time they enjoy their pool by heating the water. This is a perfect application for active solar heating. Solar collectors can be mounted on the roof of a nearby building, often on a tool shed or small structure that houses the pool's filter. Using the pool's pump, water is diverted to circulate through the collector, where it is warmed and returned back to the pool.
