The Active Solar Heating System for Hot Water

A standard active solar heating system is called "active" because it employs a pump to move water or heating fluid through the solar heating panels. Because it employs a pump, this system can afford to have the main hot water storage tank below the panels and it is usually situated on the ground, in the same location as regular hot water systems.

The photovoltaic panel both acts as a switch to operate the pump and also provides power to the pump. The pump will only operate when there is sufficient sunlight to heat water effectively, ensuring no unnecessary heat loss in cloudy conditions or at night time. In many cases, the heat collecting panels, PV panel and pump can be added to existing hot water equipment, reducing the overall cost.

The components of an active solar heating system for hot water is pictured below:

In areas that are prone to frost, it is common for the solar heating tubes to contain antifreeze so that the system is not damaged in the cold. The antifreeze obviously needs to be kept separate from the household water, and is contained in a sealed pipe loop that runs through the water tank and exchanges its heat with the water in the tank.

These systems also employ a heating element or gas burner as a backup in case of cloudy weather. The heater will be activated by the thermostat when the temperature inside the water tank drops below the pre-set level. The backup heater is most commonly gas or electricity. The backup is necessary since the solar heating panels themselves are not sufficient to supply 100% of a home's hot water needs. It is unrealistic to expect any solar heating system to be able to do this.