Solar hot water heaters are small (or large, depending on design) heaters that use the sun to warm water. This warmed water can then be used for cooking, washing, bathing, or even camping, depending on the device. Though it might seem like the water would be warm at best, using a properly made solar heater can make water piping hot – so much so that it can burn you if you’re not careful.
The design used in this article is for a simple, small 1 gallon hot water heater. Because it is portable, this design is ideal for remote cabins or camping trips where hot water won’t be available. If you need more than 1 gallon, this design can be used on a larger scale, though a pump might be necessary to transport the water from tank to home.
Step 1 – Container
A container of some type is needed. If you’re planning to cook with this water or use it to make beverages, it is best to choose a glass container, as warming up plastics can release toxins into the liquid, some of which may cause cancer. If you’re not going to be consuming the water, plastic is the best option, as it is not breakable, and is lighter (and cheaper) than glass.
For the article I used a 1 gallon plastic jug of spring water from the Dollar Tree.
Step 2 – Spray Paint
You will need some black spray paint that is intended for plastics. If you get a version that is not intended for plastics, it may scratch off or leave a residue on things that touch it. I use black enamel for mine.
Remove the cap from the jug (which should be empty). Pound a stick or broom handle into the ground and place the jug on top of it (so that the handle goes into the opening of the jug. Shake the spray paint, then hold it at arm’s length and move it in wide motions while spraying the jug. The first coat should be thin, and may have a few bare patches. This is fine, as the goal is to avoid having black paint run off.
Wait for the paint to dry, then give it another coat. Give it as many coats as necessary, allowing it to dry between each coat.
Step 3 – Sun
Solar water heaters require the sun (of course). Fill the jug with water, then screw the cap on tightly and place it in direct sunlight. This also applies with commercial water filters that are solar powered.
Depending on where you live, this may not get the jug hot enough. If that is the case, purchase aluminum duct tape and a sheet of cardstock. Tape the aluminum tape to one side and then lay it under the jug (shiny side up) so that it reflects the sunlight back onto the jug. Be careful not to burn yourself.