Heating of the water:Thermo Siphon mechanism is the principle which is used in the working of the solar water heater. This mechanism ensures all the water in the solar water heater gets heated up automatically. Thermo siphon refers to a method of passive heat exchange based on natural convection, which circulates liquid without the necessity of a mechanical pump. Once the water in the collectors starts heating, it becomes lighter in weight and thus starts moving upwards. The collectors are connected both at bottom and the top positions of the tank. Thus, when this water starts moving upwards, the cold water from the tank takes its position in the collector. This creates a cycle and automatically heats all the cold water in the tank.
Preserving the heated water: With the help of insulation material like PUF and vacuum, the solar water heater is insulated from any possible heat loss from the hot water being stored in it. This helps it maintain the heat in the stored water for up to 72 hours with any additional heating of the water.
Evacuated Tube Collector [ETC] Solar Water Heaters: Evacuated Tube Solar Water Heater contains glass tubes as collectors of sunlight to heat water. The glass tubes are connected to the solar water heater tank through which water is passed inside them. Each glass tube has two layers, between which vacuum is maintained. The inner tube is coated with a paste of copper and aluminum nitrate, a material which heats up as soon as sunlight touches it, thus heating water inside the glass tube and stopping heat loss due to vacuum. It is a technology developed by NASA to heat water and keep it hot in outer space where the temperature falls way below -50 degrees Celsius. This product is the latest technology in the solar water heater segment but has its pros and cons.
Flat Plate Collector [FPC] Solar Water Heaters: This is the traditional form of solar water heater wherein copper tubes are used to heat water. The collector of sunlight for this type of solar water heater contains copper tubes through which water is circulated. As the copper tubes heat up, the water inside them also heats up. Though this technology is outdated, there are still a few pros which cannot be matched by the latest technology products. Therefore this product is still present in the market.