Solar Thermal Hot Water Systems
The following information will help you understand how solar thermal collectors convert the sun's energy into heat for warming of water. Solar thermal technologies use the sun’s heat energy to heat substances (such as water or air) for applications such as space heating, pool heating and water heating for homes and businesses. Solar thermal collectors can be mounted on the roof or wall of a building that has exposure to the sun.
Solar energy can heat water for at least four different applications:
- potable (drinking) and service use (washing) use in homes
- potable and service use in commercial, and institutional and industrial facilities
- radiant floor heating
- swimming pools (indoor or outdoor).
Almost all applications use collectors, which are aimed at the sun to collect as much radiant heat as possible. From top to bottom, the three basic types of collectors listed below, offer increasing collection efficiency and increasing cost of installation.
- seasonal collectors (these units have a simple design and often circulate water through plastic pipes, which offer little protection from freezing)
- flat plate collectors (these units circulate an anti-freeze fluid through insulated pipes, and release the collected heat through the use of a heat exchanger)
- evacuated tube collectors (these are highly insulated glass cylinders which maximize the absorption of heat and minimize the loss of heat from the system).
The number of collectors required for a site depends on a number of factors, such as:
- the size of your load (ie: how much water do you need to heat)
- the efficiency of the unit
- the amount of solar radiation at the site
- the amount of storage available
Collectors should be aimed as south as possible, and installations require unobstructed access to the sun's path in all four seasons.
