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Solar heating: A guide
A solar heating system can reduce monthly electric costs, provide clean energy, and meet the entire heating needs of a home. Upon initial investigation, there may seem to be an overwhelming number of solar system installation options. Let us remember, however, that these complex heating systems are just a way to collect, store, and disburse the sun’s heat and energy within a home. Two basic systems exist, passive and active solar heating. Solar space heating can consist of either one, or a combination of both, of these systems. Passive solar heating systems use building design features to gather warmth from the sun. Many passive systems consist of large, south-facing windows that allow large amounts of sunlight to enter the home. The sunlight then hits a material that can hold and store the heat, known as thermal mass. Depending on the home, the thermal mass can either be flooring that is directly hit by sunlight (direct-gain systems), or built into walls (indirect-gain systems). Thermal mass can be masonry, tiles, concrete, or even water-filled tubes. Because heat is absorbed and stored during sunlight hours, the thermal mass prevents the home from overheating; at night, the thermal mass releases the stored heat, keeping the home warm even in darkness. For thermal mass to be most effective, a home must be designed so that air circulates freely throughout to carry the heat from the thermal mass to cooler places. This can be accomplished with a central staircase, venting, and open doors. Because passive systems rely so much on design, they are best installed during construction. Passive systems are less costly than active systems, but are very difficult to retrofit into an existing home. Active solar heating systems, which can easily be retrofit into a home, rely on solar collectors, usually placed on the roof of a home, to gather the sun’s energy. Two types of active solar heating systems exist; one system uses a liquid medium (usually an anti-freeze solution) to capture and transfer heat, and the other uses air. The most common type of solar collector is the flat plate design, which is an insulated, weatherproof box with a black absorber plate under a transparent cover. Integral and evacuated tube solar collectors also exist, but use can be limited in cold weather areas. A solar collector works much the same with either liquid or air. While in the collector, the fluid or air heats as the black absorber plate takes in energy from the sun. A pump or fan then either pulls the heated water into the home, and deposits in a storage tank, or blows the heated air from the collector into the home. Air based systems can be mounted on a roof for individual room heat, and usually have an air-to-water heat exchanger to supply heat for the hot water system. Liquid systems fit well into homes with radiant heating systems, like underfloor heating, or boilers and radiators, because the hot water can be pumped directly from the solar collector throughout the existing network If you're tired of reading on a computer's screen and would rather read a book, here's the one we recommend: The Homeowner's Guide to Renewable Energy: Achieving Energy Independence Through Solar, Wind, Biomass And Hydropower Related links: Solar heating systems for your house Passive solar heating basics - Understanding how it works The nuts and bolts of home solar power The best passive solar design? Return from Solar heating to 
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