Solar Hot Water Panels
Solar hot water panels differ from the traditionally pictured PV (photovoltaic) cells used in solar energy systems. Solar hot water panels, or collectors, do not convert the sun into electricity as PV cells do, but instead trap the suns heat and transfer it to liquid running through the panels which then runs into your house and stores hot water in storage tanks, ready and waiting to be used throughout the home. As you consider the type of solar hot water panels to get there are two basic areas to consider:
- Types of collectors (panels)
- Solar hot water panels in the system
There are three types of solar collector plates used for home solar hot water systems.
- Flat-plate collectors
- Integral collector-storage systems
- Evacuated-tube collectors
Flat plate collectors are the simplest type of collector and exist in two basic variations: glazed and unglazed. The typical build of the glazed collector consists of insulated boxes with a dark absorber plate under a few glass or plastic covers. Un-glazed flat plate collectors are generally used for solar pool heating and do not have the covers or insulated box.
Integral collector-storage systems, also called ICS or “batch” systems include the storage as an integrated part of the system.
Evacuated-tube collectors, more ubiquitous in U.S. commercial solar applications, utilize parallel rows of transparent glass tubes which have had the air vacuumed out, or “evacuated.” These hot water panels are quite efficient because they contain a fin which decreases radiative heat loss.
Solar Hot Water Panels in the System
Collectors affect the entirety of the rest of the system, as they are responsible for the actual heating of the water itself, and the various methods of heating the water in the panels require different systems to support them. A basic understanding of a solar hot water system, and how the panels fit that system, will help you choose the best panels for your needs.
All solar hot water systems begin at the collector. Rays from the sun strike the collectors and the heat is transferred to the obviously named heat-transfer fluid, sometimes the exchange is through air-to-liquid to the water itself, though more often it is a specialized fluid in a liquid-to-liquid exchange which carries the heat to the water. All of this fluid is moved through the system by the pump, which varies in strength depending on the type of heat-exchange fluid used as some require higher pressure than others, while some require no pump at all.
Once the sun rays have gone through the collectors to the fluid, which has been pumped through the system by the pump, it must be stored in some manner. That brings us to the storage tank, the place where the hot water is stored, ready for use throughout the home. For a pool-heating system, this will be the pool itself, but in a home there will be more options and considerations, such as capacity and insulation.
Solar hot water panels, or “collectors” are the front-line for your system and will influence the way the rest of the system functions. Make sure you understand what you’re getting and feel free to ask your professional installation contractor any questions you may have.