The principle of the Flat Panel Solar Hot Water Collector system is actually very simple. They generally comprise of the following components:
Cool water from the tank enters the copper pipe within the flat panel collector. The copper pipe within the flat panel collector is bonded to a UV absorber plate, which enhances the ability to absorb and convert the sun's energy into hot water.
As demonstrated in the image below, this absorber plate/copper pipe is installed inside an aluminium frame with fibre-glass insulation backing and hardened glass top. The glass is most often tempered glass, ranging from 3mm to 4mm thick. The thicker the glass the better the resistance to extreme weather lements; such as hail.
The sun heats up the absorber plate and transfer’s the heat to the copper pipe which in turn heats the water.
Flat Panel Collectors generally work well in hotter climates as ambient temperature will affect how hot the copper pipe will get.
In reverse condition, if it can go to near zero degree’s at night time, the water can freeze, expand and split the piping. In susch area's, anti-freeze protection is required, which starts the circulation pump when the temperature falls below certain levels. Circulation of the water prevents its ability to freeze.
In a hot, sunny climates these collectors can work nearly as well as evacuated tube collectors, though over time they loose their efficiency with calcification in the piping and lime scale build up in the inside of the glass panel, which in-turn restricts the amount on sunlight that passes through the glass and onto the absorber plate.