DIY Solar Water Heater Collectors: Building Tips and Ideas

Taking on the task of building DIY solar water heater collectors brings its own challenges, particularly in designing the collector.

How does one craft an efficient solar panel?

To assist you in this endeavor, we have explored a range of innovative ideas. These include using everyday items like empty PET bottles and cans to advanced solutions such as Fresnel lenses. In this article, we showcase some of these creative approaches for your consideration.

Each concept is accompanied by a reference link, enabling you to explore further and gain more detailed insights for your DIY solar water heater project.

Installing a solar panel

DIY solar water heater collectors - Things to consider

Types of collectors

Solar collectors are predominantly of two types: flat-plate and evacuated tube.

Flat-plate collectors are widely used due to their simplicity and cost-effectiveness. They consist of a flat absorber plate, typically made of copper or aluminum, which transfers solar heat to the water or antifreeze solution running through pipes attached to the plate.

On the other hand, evacuated tube collectors are more efficient but also more expensive. They consist of rows of parallel, transparent tubes, each enclosing a metal absorber tube. This design minimizes heat loss, making evacuated tube collectors particularly effective in colder climates and overcast conditions.

Both types have their unique advantages and are chosen based on specific needs and environmental factors.

Ensure proper sizing and orientation

The sizing of a solar collector is a critical aspect that depends on the household's water usage and the local climate. A general rule is to allocate approximately 20 square feet of collector area for each of the first two family members and 8-14 square feet for each additional member. However, this can vary based on the local sunshine availability and intensity.

The orientation and tilt of the solar collector are crucial for maximizing solar energy absorption. In the Northern Hemisphere, the collector should generally face true south, while in the Southern Hemisphere, it should face true north. The tilt angle is equally important and should be adjusted according to the latitude of the location.

Materials and tools you might need

  • Copper pipes or black hose pipe
  • Plywood (4ft x 8ft)
  • Black paint (heat resistant)
  • Glass sheet (same size as plywood)
  • Insulation material (like fiberglass)
  • Metal brackets
  • Sealant (silicone-based)
  • Water tank
  • Soldering materials or hose connectors
  • Tools: Saw, drill, screwdriver, etc.

Basic instructions

Step 1: Building the heat absorber panel

Start by cutting the plywood to the desired size for your solar panel.

This will form the base on which the copper pipes or hose will be mounted. Paint the plywood with black heat-resistant paint to maximize heat absorption.

Once dry, layout your copper pipes or hose in a serpentine pattern to cover the majority of the panel. Secure the pipes or hose to the plywood with metal brackets, ensuring they are tightly fixed.

Step 2: Insulation and sealing

Around the edges of the plywood, add insulation material to minimize heat loss.

Next, place the glass sheet on top of the plywood, covering the pipes or hose.

The glass acts as a greenhouse, trapping heat inside the panel. Seal all edges with silicone-based sealant to make the unit airtight and water-resistant.

Step 3: Connecting to the water tank

Connect one end of the pipe/hose system to the bottom of your water tank, where the cold water enters. The other end should be connected to the top of the tank, where the heated water will return. Ensure all connections are secure and leak-free, using solder for copper pipes or appropriate hose connectors.

Step 4: Installation and orientation

Mount the solar panel on a roof or a sturdy frame, ensuring it faces the sun for the maximum part of the day. The ideal angle depends on your geographical location but typically ranges from 30 to 60 degrees. Secure the panel with metal brackets to withstand weather conditions.

Step 5: Testing and usage

Fill the water tank and allow the system to heat up for several hours on a sunny day. Check the temperature of the water periodically. Initially, adjustments may be required to ensure optimal performance.

Other creative DIY solar collector designs

Idea #1

In this design, the handyman used copper pipes for their excellent thermal conductivity. As seen in the video, it took some time to measure, cut, and solder all the pipes and elbows together, but I think it was totally worth the effort!

If you're new to soldering, don't worry – it's not as complicated as it might seem and is a fantastic skill to learn for any DIY home project. You'll need a sturdy board to mount the interconnected copper pipes. And, of course, don't forget to top it all off with a glass cover for that sleek, finished look.

What's really cool about this solar water heater is its compactness. It resembles a window filled with pipes. The best part? It quickly heats up water, reaching temperatures above 65°C, even on days when the air temperature is a chilly 9°C to 11°C. Eager to try it out? All the detailed instructions are just a click away – follow the link below to get started!

Idea #2

Back to copper.

If you're willing to invest more time, money, and artisanal effort, consider making connected panels following detailed instructions.

These panels are more powerful and result in greater savings over time. The cost to build each panel ranges between $450 and $500.

According to this handyman, he installed 20 panels that can collect around 300,000 BTU, an amount more than sufficient to comfortably heat a house for an entire day.

Idea #3

DIY solar panel by DavidDIY solar panel by David

David Norman from Florida is also sharing his experience with us about a DIY solar water heater adventure.

In his project, the most important material is PEX tubing and the total cost, together with the wooden box painted in black, is $280. The solar system is connected to the standard electric water heater as an alternative source of energy. The bypass valves are used for diverting. This solar water heater is excellent for the summer savings; it is inexpensive and ideal for small households.

Idea #4

Building a solar water heater is something anyone can try, but the real impact lies in the idea.

Jose Alano, a retired mechanic from Brazil, won the Superecologia prize with his innovative invention – the plastic bottle solar water heater.

The system is based on thermosyphon technology, which allows for water circulation without a mechanical pump, driven solely by temperature differences. If you're interested in experimenting with this design, start in the summer or a warmer climate.

Gather plastic bottles and milk cartons, purchase some PVC pipes and small parts, get black matte paint... and give it a go.

Jose has patented his design and made it available for public use, provided it's not for profit. You can check it out here.

Idea #5

How can you increase the efficiency of a solar collector?

Many innovators recommend shaping it into a parabolic trough. This design features a surface covered with a mirror to concentrate sunlight and heat onto its focal point. In a DIY version, you can create a mirror effect using various materials, depending on your budget and skills.

For instance, Dan Rojas presents a small model made of PVC pipes covered with reflective material. His solar water heating system includes an insulated storage tank with a heat exchanger, as is typical in such setups.

Idea #6

This system, inspired by the previous one, is also parabolic and follows the sun, though it is more complex.

In a series of six videos, the creator Andrew Ancel Gray explains step by step how to build this impressive solar collector. The design features four parabolic troughs that gather energy to heat an 80-gallon tank. Its dual-axis movements ensure optimal positioning, incorporating sophisticated solutions like a heliostat and infrared beam break rotation counters.

While it may seem complicated and costly, each component plays a crucial role, resulting in a high-quality solar heating solution.

Idea #7

Have you heard about the Fresnel lens?

This old invention, originally used to amplify lighthouse light, is now a topic of research in modern solar energy concentration technology. While there are notable limitations to using Fresnel lenses in solar power plants, solar energy enthusiasts have experimented with these lenses in DIY water heating systems with promising results. Take a look at the brief explanation of the principle and explore a water heater project that utilizes a lens and a black-painted storage tank. You'll find that water heats up extremely quickly.


Building a homemade solar panel for water heating is a practical and sustainable project that can provide long-term benefits. While the initial setup requires some effort, the satisfaction of using solar energy for your daily needs is immeasurable. Remember, safety comes first; ensure all installations are secure and seek professional advice if needed.


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