Solar water heaters are divided into two kinds of systems: active or passive. Active solar systems readily upon moving mechanical parts in order to transport heat, while passive units simply use the sun to accomplish this action. Solar Water Heaters are economical, technically feasible, and commercially available and are used in many countries. Solar Water Heaters make use of flat – plate collectors, storage tank, control mechanism, pump and pipes etc. Solar water heaters are MUCH more efficient than that, taking the heat from the sun and using it to directly heat the water. Basically, it's like putting a big tub of water on your roof.
Systems that meet the standard contain the SRCC OG-300 label. Systems include a back-up water heating system to ensure that hot water is always available. The back-up heating system can use electric, natural gas, or propane and is controlled by a thermostat.
RECs are payable if you are installing a system in a new dwelling or installing a solar water heater to replace an electric water heater in an existing lodging. You can also get a partial RECs rebate for replacing an old electric system. Recirculation systems are a specific type of open-loop system that provides free protection. They use the system pump to circulate warm water from storage tanks through collectors and exposed piping when temperatures approach freezing.
Heat energy is transferred from the collector to the water storage tank. In some water heaters, hot fluid is pumped from the collector to the storage tank. Heaters 10 years old or older probably have an efficiency of no higher than 50 percent. Heating water with the sun also means long-term benefits, such as being cushioned from future fuel shortages and price increases, and environmental benefits.