Earlier, I published an article about what is a solar water heater. In continuation with that, here is an article to explain the working of the solar water heater.
As soon as sunshine hits the collector, the water inside gets heated immediately. If the flowing pump is regulated by a PV panel, the pump starts revolving as the PV panel is started by the same sunshine. This direct current (DC) motor pump then shifts water from the tank through the collector and finally back to the tank.
The intensity of sun keeps changing throughout the day. As the intensity of sun changes, the circulating pump also changes its speed accordingly. As a result, by the end of the day, the water in the tank has been rotated several times through the collector and has been heated to usable hot water temperatures.
When the water in the collector reaches the temperature of 15-20 degree Fahrenheit, the circulating pump is regulated with the help of an electronic differential controller, a sensor at the outlet of the collector and a sensor at the bottom of the tank sets in motion the circulating pump.
The water then circulates from the collector and the tank through the pump. This process persists as long as the water temperature at the collector reaches 5° F higher than that in the bottom of the tank. However, if the temperature difference reduces further, the controller automatically shuts off the pump.
Moreover, common appliance timers also control system operation. Through this appliance, timer is placed to function during that specific time of the day when solar radiation is available to heat the potable water. It is essential that the timers used in these systems have battery back-up as a feature in the situation of power failures.
A backup electrical element becomes important in case of inadequate sunshine or high hot water demand. The check valve prevents loss or shortage of heat when the circulating pump is switched off. The circulating pump consumes only a little amount of electricity.