There are two basic components to a solar water heater: the collection devise and circulation system.
While collection devises are essentially the same in solar water heaters, there are three different collectors that have pros and cons of each. These are placed in a sunny location, typically the roof.
- Batch Collector. This is a large dark tank inside an insulated box that stores the water. This system is best used in climates that freezing is not a concern.
- Flat Plate Collector. The second type of collector typically consists of copper tubes fitted to flat plates in an insulated box with a glass cover.
- Evacuated Tube Collector. This works on the same concept as your old lunch thermos. These are the most efficient of the collectors and can effectively work in colder climates and overcast.
Solar water heater circulation systems are either active or passive and direct or indirect. A passive circulation system does not require a pump and relies on the house water pressure and convection to circulate water to the storage tank. Passive systems are not compatible in colder climates as they are prone to freezing. A direct system uses a pump to send the water from the collector to the storage tank. Direct systems are the most popular for solar water heaters in the United States.
In a direct system, the heated water is sent to a tankless water heater or directly to use. As with passive circulation, direct systems do not fare well in colder climates. A solar water heater that employs an indirect system uses a non-freezing liquid to transfer the sun’s heat to water in a storage tank. The sun warms the fluid in the collectors and the fluid passes through a storage tank, heating the water.
There never has been a better time to be green and a solar water heater is an easy way to start.
