How does the solar water heater work?
20 Mar 2013

The sun’s rays hit the solar panel and transfer the thermal energy to the panel’s copper surface (the absorber); this heat is then transferred to the fluid (a mixture of distilled water and glycol) running inside the copper tubes which in turn heats the domestic water inside the boiler.

There are 2 different fluid circulating systems:

a. Natural circulation; when heated, the fluid becomes less dense and lighter and ascends towards to top of the collector into the closed circuit chamber in the boiler. Once inside the boiler’s closed circuit, the heat is transferred into the sanitary water you use in your home; during this process (ceding thermal energy into the sanitary water), the fluid becomes colder and denser and therefore descends to the bottom of the closed circuit chamber in the boiler channeling it to the bottom of the collector. At this point the process restarts; there is no need for any pump as long as the boiler is located above the panel/s. This process runs by itself generated by the heat of the sun;

b. Forced circulation: instead of the fluid flowing by itself following the laws of thermodynamics, the fluid is forced through the panels and the closed circuit by a small electric pump. An electronic control system ensures that the fluid circulates keeping the temperature in the panel is higher than that in the boiler. Forced circulation is used when the boiler is installed below the panel/s.