What Is A Solar Water Heater?

Mechanical pumps and differential controllers are used in active solar hot water systems to control and guide the flow of the heat-transfer fluid or water from the solar collector to the tank. When the water in the tank cools below the collector’s temperature, the controllers detect the temperature differential between it and the water in the tank and activate the pump. Some pumps use line power (mains electricity), while others use power produced by solar photovoltaic panels. While some solar-powered systems simply circulate the fluid when the Sun is out and store the heated water in well-insulated tanks for space heating at night, others rely on mains energy as a backup for nights and cloudy days. Since the flow of water in active solar hot water systems is not solely dependent on gravity, the water storage tanks can be placed inside the roof area or anywhere else that will reduce heat loss to the cold air. Because of this, these tanks can be integrated with hot water cylinders in household space heating systems, and the solar hot water system can be utilised to pre-heat water in the cylinder in the winter for space heating.

The most effective passive systems, which rely on gravity rather than power, are found in warm climes without nighttime or winters freezing. Some passive systems employ a thermosiphon setup that relies on convective and gravitational heat transfers. Gravity pulls cold water from a height down to the solar collector, where it runs through the collector and heats up before rising by convection to return to the storage tank. The integrated collector storage system is another kind of passive system. In this system, the collector serves as the tank’s top and heats the water there.