Solar Water Heating

Storage Tank and Ancillary Equipment

A solar water heating system generally requires a well-insulated storage tank to hold the heated water. The storage tank is often equipped with an auxiliary electric heater (or gas heater) to boost the temperature of the heated water when the thermal output of the solar collectors is not sufficient to meet the heating requirements. This may happen when solar energy is not available or insufficient, for example, at night, on a cloudy day, or in the cooler months of the year.

Other ancillary equipment includes controller and circulating pump, safety devices like temperature/pressure (T/P) relief valve and tempering (water mixing) valve. The controller monitors the collector and storage temperatures with temperature sensors, and operate a circulating pump at the appropriate temperature differential. A T/P relief valve releases water (through a discharge pipe to drain) if either the temperature or the pressure inside the storage tank gets too high. A tempering valve is used to control the temperature of the hot water being delivered to the user so as to prevent burns. The valve mixes the hot water with tap water to ensure that the water delivered to the user is kept below a safe temperature.