A solar water heater / solar geyser work by transferring thermal energy of the sun directly to water through vacuum tubes, Vacuum tubes are made up of dual layer of borosilicate glass with complete vacuum in between to insulate the inner layer from heat loss. The inner layer of the tube is coated with special three layers of copper, stainless steel and aluminum each which efficiently absorb the suns energy and immediately transfer it to water that is being held inside the inner tube.
The tubes are directly attached to the main water tank of the water heater / geyser which is mounted on the top end of the tubes and supported by a frame. As the cold water inside the tubes gets hot it becomes lighter than the cold-water present inside the tank and thus convection takes place inside the system constantly rotating the water inside the system and increasing the overall temperature of water in the solar water heater.
The tank is insulated by a 60 mm insulation that helps the system retain hot water helping constant delivery of hot water day in and night out.
Therefore, as explained above a solar water heater / geyser work with the use of minimal mechanics enhancing the life of the system by many years.