How Do Solar Hot Water Systems Work?

Now let’s see how a typical hot water system works. First we’ll go into solar panel based hot water systems.

(You can jump to Solar Heat Pump Systems if you are only interested in those)

Otherwise keep reading…

Solar Panel Hot Water Systems

Here’s a very simplified diagram that explains the 3 main components of any solar panel based solar hot water system: The panel, the storage tank and the boost.

Let’s go through the diagram:

1. Cold Water at mains pressure enters the solar panel. The panel is designed to absorb the sun’s heat and transfer it to the water as efficiently as possible.

2. The sun heats up the water, how much by depends on the strength of the sun at that moment in time.

3. The hot water moves to a hot water storage tank. As the hot water comes in it pushes colder water to the bottom of the tank (because hot water rises, so cold water must drop) where its only option is to go back into the solar panel to get hotter. As this cycle repeats the water in the tank will get hotter and hotter until it reaches the system’s design temperature.

4. If the sun isn’t strong enough to get the water in the tank to the desired temperature (usually 55 to 60 degrees Celsius) then an electric or gas booster will kick in to add the extra heat required.

That’s it!

If that very high-level overview is as technical as you want to get and you are happy to let your installer decide the detailed configuration that best suits your home, then that’s cool and you may want to skip the next section and go straight to What Size System Do I Need?.

If you want to understand all the different configuration options you have and why you or your installer may choose one over the other, then carry on to the next section where we will start with your options when it comes to the actual panels:

Read next: The solar hot water panel (flat plate or evacuated tubes?)