In actual fact not all solar systems need to be serviced. When we refer to the servicing of a system we are talking about the indirect solar systems. (Click here for more info on direct vs indirect)
Indirect solar geysers are special in that they use a specific liquid called “Glycol”. This is actually short for Monopropylene Glycol and is a fancy term for anti-freeze. Its function is the same as that of your antifreeze in your car. Its purpose is to stop the water in the panels from freezing in winter.
Over a period of a calendar year and especially during the hot summer months, the constant expansion and contraction within the panels causes the glycol levels in the panels to drop. This is released through an expansion valve.
Naturally, when the level of fluid in the panels decrease, the ability for the heat to transfer from the collector to the tank is reduced dramatically. This in turn reduces the efficiency of the system
Reduced fluid levels also put strain on the collectors in winter and may cause the panels to crack.
Lastly, if you are a seasonal holiday maker, when you leave the house over december – no one is using the hot water that your solar system is producing. This causes the temperature to reach boiling point in some cases. When this happens, your geysers safety valve will release excess pressure from the boiling water and allow the system to cool down. The same happens with the glycol in the panels, however there is no way to replenish the levels without some manual intervention.