DIY Solar Water Heater: 10 Designs and How to Build Them

Solar water heaters use naturally occurring sunlight to heat the water that flows through them. This is a more environmentally friendly and direct method compared to using electricity and gas. They can be more efficient because there is no energy loss by converting one energy form to another, for example when electrical water heaters are powered by solar panels. Best news is – you can build one yourself! DIY solar water heaters are incredibly easy to make.

What makes them even more exciting is that it is relatively easy to build them yourself. In this article, we will discuss a number of possible solar water heaters that anyone with some basic handyman skills can make. Of each of these, we will briefly discuss their main characteristics and how to build them.

DIY Solar Water Heater – Top 10 Designs

1. Single-tank batch heater

DIY single-tank batch heater

The first design we’ll discuss is one of the easiest to build and one of the cheapest since it tries to use as much garbage as possible. Firstly, the inside of an old water tank is taken out of its casing and the insulation removed. Then, a trapezoid box is made from sheets of plywood, so that the largest side is open and faces the sun, and insulated. Thirdly, the water tank is fit inside the box, resting on 2 pieces of plywood, cut for this. After making the plumbing connection, the remaining open side of the box is covered with a glass panel.

2. Vertical three-tank batch heater

Similar in concept to the previous design, this DIY solar heater has the advantages of having a larger collector area and a larger storage volume. The only difference in the building plan is that here, a number of tanks, often 3, are connected in series. By adding extra insulation to the last tanks, the water that will be used first is kept warmest.

3. Beer-bottle Solar Powered Water Heater

This cheap DIY solar water heater uses beer bottles to make the pipes through which the water flows. Alternatively, one may use aluminum cans or plastic bottles. After stacking several columns and connecting them in a watertight way, they are painted black to increase the amount of absorbed solar radiation. Finally, the pipes are put in an insulated box with a transparent front side to minimize heat loss to the environment.

4. Closed-loop DIY solar water heater

DIY solar water heater drawing of a closed-loop solar water heater. We are also shown how the whole process works.

For this low-maintenance water heater, the entire inner pipe system is a closed loop to avoid bursting pipes when it’s freezing. To make watertight connections between the copper pipes each end is sanded, washed, and soldered together. The coil is painted black and put inside a rectangular-shaped black wooden box with a glass top panel, with the slightly longer ends of the coil sticking out. Finally, water tightness can be tested by connecting the tubes to a pressurized water faucet.

5. Building-integrated solar water heater

This DIY solar water heater achieves the same goal as the previous design: to eliminate the risk of bursting pipes by freezing water. However, it does this through a different method. By incorporating the collector box inside a well-insulated attic, freezing water is unlikely. The water pipes, that are connected to each other and painted black, will be exposed to the sunlight through a skylight underneath which the water heater hangs.

6. Greenhouse solar water heater

solar water heater that generates a greenhouse effect

This variant is closely related to the previous example in that the entire collector is kept at a higher ambient temperature. However, here this is done by placing it entirely in a greenhouse. Once again, pipes are connected in a watertight way, painted black, and put inside box with glass top panel. Lastly, connect your new solar heater to water inlets and outlets.

7. Thermosyphon DIY solar water heater

The inner pipe system of this heater is organized in such a way that water flows from down to up in every section. The black-painted pipes are put inside a wooden box with glass top panel. But having the water inlet of the collector at the bottom and the outlet at the top, the thermosyphon effect will make hot water rise and suck cold water in. This negates the need for an extra water pump.

8. Solar shower

improvised shower area with buckets as reservoirs and wooden walls surrounding the shower. There's also a bench inside the area.

We’ve included this type of heater because of its simplicity yet surprising effectiveness. A simple black bag is hung in direct sunlight, supported by a wooden frame, and connected to a closely located (inside or outside) shower with a garden hose. The major drawback is that warm water is only available after the bag has been heated for some time, because of the lack of insulation. You can also use buckets or small water tanks.

9. Energy efficient solar water heater

This slightly more challenging and more expensive DIY solar water heater was designed to maximize energy efficiency. Rather than building the collector housing from wood as in the previous examples, this one is made from aluminum. A selective paint, which has a higher absorbance of infrared radiation compared to ordinary black paint, is applied. The pipes, that have metal fins to absorb and transfer more heat directly to the pipes, are connected to each other and to water inlets and outlets.

10. DIY Solar water heater with maximum surface area

This DIY solar water heater intends to maximize the surface area of which the water is exposed to solar radiation. 2 thin metal sheets, covering the entire collector box they will be put in, are glued together. This leaves a small gap through which water flows. Nonetheless, the increased efficiency comes with a downside. The water comes in direct contact with the plastic of the sheets and the glue that holds them together. Consequently, it renders the water unsuitable for drinking purposes.

Final Thoughts

As we’ve shown, there is a wide variety of design possibilities to build your own solar water collector. Off course, you don’t have to stick exactly to 1 of these designs. Feel free to combine different features as you see fit. Why not build a thermosyphon solar heater in which the water flows in between 2 thin sheets rather than a complex of pipes? Or paint cheap beer cans with selective paint to increase efficiency? Good luck with your build, and please share how your project turned out in the comments below!

IMAGE SOURCE: 12, 3, 4

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