Flat Plate Collector Solar Water Heater

There are several different ways to heat water for use in the home. Solar water heating systems that use flat plate solar collectors to capture the suns energy can be classed as either direct or indirect systems by the way in which they transfer the heat around the system. In order to heat your water successfully and use it during both the day and the night, you will need to have both a solar collector to capture the heat and transfer it to the water and also a hot water tank to store this hot water for use as needed.

A direct solar water heating system, also known as an active open-loop system, uses a pump to circulate the water around the system. The cooler water is pumped directly from the home to a central water storage or immersion tank and passes through the solar collector for heating. The hot water leaves the flat plate collector and returns back to the tank flowing in a continuous loop. From there, the water is pumped back into the house as hot usable water.

An indirect hot water systems, which are also known as closed-loop systems, differs from the previous thermosyphon system in that it uses a heat exchanger which is separate from the solar flat plate collector to heat the water in the storage tank.
Indirect hot water systems are active systems and require pumps to circulate the heat transfer liquid around the closed-loop system from the collector to the heat exchanger in the tank. The system contains an antifreeze solution, typically a 50% Glycol/water mixture, in the primary closed-loop instead of just water which is heated and is kept separate from the main domestic hot water supply.