The types of solar hot water systems vary but they all consist of collectors and a storage tank and they all use the sun’s thermal heat to warm water. There are 3 types of circulation systems and collectors, which are used when designing the best system for each circumstance.
In designing solar thermal systems, roof direction, shading, temperature and water usage are the main factors in determining the best system for your needs. Direct systems cannot be used in climates where the temperatures can reach freezing temperatures
There are two main types of systems: Active systems which have circulating pumps and controls and passive systems which don’t.
Active Solar Hot Water Heaters
There are two type of active hot waters systems
- Direct, which circulates water through the collectors. The water is then directed back into the home for use. This system works best in areas that do not experience extreme freezing temperatures.
- Indirect Circulating Systems circulates a non-freezing heat transfer liquid through the pipes and heat exchanger, which then heats the water used in the home. This system is best suited for areas with freezing temperatures.
Passive Solar Water Heating Systems
There are two types of passive solar water heating systems. While these systems are typically less expensive than direct solar water heating systems, they are not as efficient. Although these systems may last longer and be more reliable.
1.Integral collector is a storage passive system which is best in areas that experience milder temperatures. They also work best in households that have high evening and daytime usage.
2.In thermosyphon systems warm water rises while cool water sinks. The collector is stored below the storage tanks so that the warm water flows into the storage tanks. While the cooler water then sinks into the collector to be heated. These are reliable systems, but tend to be more expensive. They also do not work with every roof design because of the heavy storage tank.
Solar Collector Types
There are three types of solar collectors used with solar water heating:
Flat Plate Collectors: These are glazed flat plate collectors housed in insulated waterproof boxes that contain a dark absorber plate under a glass or plastic cover. Unglazed collectors are used for heating pools.
Evacuated Tube Solar Collectors: Glass tubes act like a thermos in principle. A glass or metal tube containing the water or fluid is surrounded by a larger glass tube. Very little heat is lost from the fluid because the space between the tubes is a vacuum. These are the most efficient collectors.
ICS or Batch Systems: ICS stands for Integrated Collector Storage Systems. These collector’s heat water in dark tanks or tubes within an insulated box, storing water until drawn. These collectors can store water for a long period of time making it very hot. The water is used with a tempering valve which mixes it with cold water before it passes onto the faucet. This type of collector cannot be used with a closed loop system, making it unusable in freezing climates.
To determine the best system for your needs it is always recommended to consult your solar professional. He/She will be able to design the system that will work best with the angle and direction of your roof, sun exposure, climate and hot water usage.