The Solatherm control unit regulates DC electricity generated by a photovoltaic array and applies it to a resistive heating element,  located in a storage hot water vessel,  to generate hot water. The microprocessor constantly monitors the water temperature in the storage vessel and energizes the heating element when sufficient power is available from the array and the water stored in the vessel is below the set temperature. (Factory set temperature 600 or 700 Celsius) When the temperature is reached the unit will turn the element off until the water temperature falls.

Once the water is up to temperature, Solatherm units with re-direct are able to direct surplus power for another purpose such as to an inverter for the house load or to a battery storage system. The controller monitors the temperature of the stored water to ensure maximum hot water is maintained.

Solatherm Control Units are independent from the grid and require no mains power connection to operate, hence, the unit will only operate and display user information when there is sufficient energy from the sun.

During periods of low solar input where there is insufficient power available to heat the stored water to 600C the independent 240V AC boost element will top up the temperature of the water in the storage vessel. The boost capacity has been set to meet the minimum volume requirements for off peak boosting in all states.

NB: Generally the independent AC boost element is connected to an off peak (controlled load) power supply. If only peak is available it is recommended to install a din rail timer and set a heating period during the early evening and/or early morning depending on the household demand. If the water in the storage vessel is higher than the 600C thermostat setting the unit will not draw any power as there is no need. If the water is below 600C during the set periods the boost element will top up the temperature to ensure hot water is available. The boost element heats approximately 125L of water. Connection via a timer will maximise solar gain during the day, minimise energy consumption and allow for ease of use. High usage households may require extended boost periods or continuous mains connection to meet high demand.