Ben’s DIY Solar Hot Water System

For sometime, I have thought how nice it would be to have a solar hot water system on my house.

Then I checked on the cost. Ouch. Even through solar hot water systems tend to have a relatively short payback time, and usually have good tax incentives, it’s still a chunk of change up front.

I figured I could do just as good with my library card, a class or two, and some salvaged materials.

First off, I bought a used solar panel for $100. It’s a 10′x4′, with extruded aluminum rails. A similar model new would cost about $1000. Even just trying to BUILD something like this myself, it would cost over $100 in parts!

Next, I started experimenting with a pump, some copper pipe, and a old water heater. After making my back yard wet way to many times, I decided I would build a tank with two copper coils inside, one for the solar panel, and one for the domestic water. The tank would be filled with water that would transfer the heat from the one pipe to the other, but prevent contamination should one pipe leak.

Here’s one of my experiments, testing heating a tub of water with the solar panel.

Obviously, a plastic tub is not going to be the permanent tank for inside my house. I did find a free steel water tank that seemed to be in pretty good condition. I thought that would make an ideal tank, as it would be about the right volume of water, and would fit the footprint of space I have available in my utility room. Unfortunately, there is no easy way to get INSIDE that tank, short of cutting the top off, so I headed to a friends house to use his fancy cutting tool, a “plasma cutter”.

Next, I will have to start bending copper tube into a coil to fit inside the tank.