As we all know using electricity to generate heat is not very efficient. The good news is that we can heat water and air using the sun as well. We'll just be focusing on solar hot water heaters in this article, but it is possible to partially heat your home with a solar heater as well.

Solar water heaters are setup almost the same as solar panels. Instead of solar cells there are a bunch of small tubes (ABS is a good material) running through a panel. These small tubes are then wrapped up so there is an insulator as well. Think of the panel as a greenhouse. The plastic/glass of the greenhouse is the outside of the panel with these small tubes running inside the greenhouse.

This setup allows the water passing through to collect quite a bit more heat.

There are two different types of solar hot water heaters. These two types are know as active and passive. An active system has a pump which pumps the water through the system while a passive system lets thermosyphoning move the water through the system.

Although passive systems are easier to build and install they aren't as efficient as active systems so we're going to be focusing on active systems. Active systems don't add much to the overall cost as all you need are some temperature sensors and a pump to move the water.

In addition to active and passive systems there are also closed and open loop systems as well. An open system pumps water out the the panel which heats it up and it is then returned to the tank. A closed system is just that. Water is pumped out to the collector and returns back to the tank. The heat is transferred to the water in the tank through a heat exchanger (think radiator).

An open system could be used if you live somewhere where the temperature never gets below 10 degrees celsius (50 degrees fahrenheit). Closed systems are better for colder climates as they are usually filled with anti-freeze and a corrosion inhibitor (something you don't really want in your water).

How big should your solar hot water heater be? Well, a family of 4 can easily generate enough hot water using a collect that's 12' x 12'.

If you have any questions feel free to leave a comment or you can contact me using the contact link at the top of the page.