Types of Solar Water Heating Systems
Pre-Heat Solar Tank System:
This type of solar water heating uses two tanks. The 1st tank is called a solar pre heat tank and is a basic solar hot water storage tank. The solar pre-heat tank is used to supplement warm water to an existing hot water tank. This type of solar water heating is the most common retrofit as it uses the existing hot water tank and needs very little retrofit to the plumbing. The existing main supply line is routed to the pre-heat tank and then drawn back into the supply line after it is heated.
The most efficient solar hot water heaters use the basic theory of stratification. In stratification the solar hot water heater is heated using thermosiphon (or a very slow pump). This slow mixing of the water means the top layers are always the hottest. As the top water is drawn into the main tank, the hottest water is always used 1st. Since the average house hold used hot water in batches (not all at once), the solar water heating system can easily supply a daily demand.
Solar with tank-less water heaters:
The principle is identical, the water is pre-heated through the solar storage tank before it enters the tank-less heater. As an example, main line water that is coming into the home at 40 degrees can be heated in a pre heat tank to say 120, if the tank-less heater is set to 140 degrees, it only has to supply 20 degrees of heat energy versus 100 degrees with out the pre-heat tank. That is significant heat savings!
Solar Combo Tank System:
These special designed solar hot water heaters are a combination of a solar pre-heat tank with an electric back up heater in one single unit. This tank uses an internal heat exchange in the bottom of the tank. The solar loop is piped through this loop and heats the water. The top of the tank contains an electric heater element to quickly top up the water temperature or aid in days of no sun.
While there are many solar pre-heat tanks with heat exchangers, there are very few that are built for the North American Market and have the proper UL certification. Solar Combo tanks are ideal for new home installations or if your existing water tank needs replacing.
NEW Compact solar water heaters:
A compact solar water heater is used for those that just want solar heating for domestic hot water. These are alternatives to the more advanced closed loop solar water heaters and have no moving parts or pump. These system are ideal in southern climates that seldom get freezing conditions and are good to 20 F (-5 C). These usually sit on the ground or are roof mounted. The 80 gallon storage tank is integrated with the solar vacuum tubes and provides hot water for a family of 4-5 persons. For more information visit compact solar water heaters.
Complete Solar Hot Water Heating Package with built in Heat Exchanger and Back up Heating Element.