A solar heating system is designed in the most optimum form in order to utilize all the energy of sun available in the day. This practice is adapted to keep the cost of solar system at minimum possible value considering that it is an expensive technology. Therefore, a solar heating system adapts a continuous and steady heating process and NOT an instant heating process. It thus does not cater for mass usage in a short time. The concept is that system is heated in a set time period (usually one sunny day) and then utilized. Typically, the system is left idle during the sun shine hours of the day and then utilized for rest of the period. This is done due to allow sufficient resident time to water for getting heated up to desired level.

In order to cater the left over margin for instant heating, the systems are usually made hybrid with a conventional geyser, where the solar part is used as a pre-heater.

The solar collector is based on vacuum tubes. The size and number of tubes depend on the heating requirement. The tubes are directly attached with the storage tank. Water from the storage tank floats inside the vacuum tubes and keeps heated. There is one outlet to allow hot water flow to the point of consumption and one inlet to allow cold water flow from the main water tank of the household.

The principal of operation is same as of gas heater. The piping is also on the similar techniques. In order to utilize max solar potential, special measures are required to keep the piping network insulated.

The system has an inbuilt optional feature of electric hybrid. There is provision of heating through electric coil as a backup, which is activated when the water temperature falls below a pre-programmed value. That is a fall back option to operate when there is no sun or the consumption is higher than normal.

There are several households that already have installed the conventional gas heating systems. The solar system can also become a hybrid with conventional gas heater. In that case, the solar heater will become a pre-heater to the original system thus resulting in lesser burner operation of the conventional heater and saving the cost of gas.

(Typical Temperature Curve of Solar Water Heating)