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DIY Solar Water Heater (A Step-by-Step Guide)


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Building a DIY solar water heater system is a great way to capture the sun's energy and save money on your hot water heating bill. Professionally installed solar heating systems can cost in the neighborhood of $9,000, but if you enjoy a DIY project you can build your own.

The hot water you collect can be used to fill a pool, hot tub, or even with your traditional heating system. This article will show you how to build a DIY solar water heater and provide you with other useful information you should know.

Soldered copper tubes

How to Build a DIY Solar Water Heater

Do a quick search on the Internet for DIY solar water heaters and you'll find plenty of different types you could build. We chose this style because it didn't require working with expensive copper tubing and soldering joints.

But in case you're looking for something different, we'll provide you with several different options so you can choose the type of project you want to tackle.

Buying Materials for DIY Solar Water Heater

Getting Started

Depending on your level of experience, you may have some of the equipment and supplies already in your garage. 

But if not, you can find the material and equipment list you'll need for this project HERE.

Trimming 2x4's on a Table Saw

Cut the Wood

  • Cut the plywood to 4' x 6' (the lumber store may do this for you)
  • Mark and cut the 2 x 4's (frame) to fit the plywood. (You should have two 6-foot pieces)
  • Cut the treated 4 x 4's (legs) to desired height
  • Using a table saw, re-saw the frame 2 x 4's to 3/4-inches - by doing this you'll be able to build two frames, one for the top (tubing) and one for the bottom (legs)
  • To make gluing easier, you can run each of the frame pieces through the table saw again. This will straighten one side
Gluing the wood for the DIY Solar Water Heater

Build the Top Frame

  • Lay the plywood on a flat surface
  • Apply a wood glue (such as Titebond III) along one edge of the frame wood
  • Connect the frame piece with glue to the plywood and use a speed square to ensure its aligned properly. Use clamps to hold in place
  • Drill countersink holes through the plywood into your frame wood, and screw the pieces together. This video will explain how
  • Repeat with each piece of your frame. Butt joint the joints together. This video will give you several different butt joint options
  • Run a bead of caulking where the inside of the frame connects to the plywood
Building the bottom frame

Build the Bottom Frame

  • Drill pocket holes into the bottom frame boards. This video explains how
  • Flip the plywood frame over so you can begin attaching the bottom frame
  • Use your impact driver to ensure all the screw heads are fully embedded from the top frame (bottom of the plywood)
  • Glue and screw the bottom frame pieces into place
  • Run a bead of caulking along the frame and plywood seam
  • Plug the pocket holes with pocket hole plugs, and trim the excess so they are flush. Use a sander or flush saw 
Paint the Solar Water Heater Frame

Paint the Frame

  • Paint the bottom frame edges where it could come in contact with another surface
  • Paint the outside edges of the bottom frame. It's not necessary to paint the entire bottom of the frame
  • Flip the frame over and paint all three sides of the top frame
  • Paint the plywood
  • Add a second coat 
Attaching the Zip Ties

Prep the Frame for Tubing

  • Find the center of your frame using a measuring tape. Draw a line through the center of the frame length wise and width wise so they meet in the dead center of the plywood
  • Using a small piece of wood, build a template that will allow you to drill the holes into the plywood in a uniform manner
  • For each zip tie, you'll need two holes to hold the tubing in place. One for input and another for output
  • On the center of each side, drill 12 holes so you can insert 6 zip ties
  • Thread the zip ties through the holes
Coiling the Tubing

Installing the Tubing

  • Starting with the zip tie closest to the outside of the frame, begin coiling the tubing. Use caution not to kink or tangle the tubing. This is best done with two people
  • Once you have coiled enough tubing to fill the 6 zip ties, drill more zip tie holes and continue coiling the tubing
  • At some point you will no longer be able to bend the tubing without kinking it. At this point you can switch to an oval shape
  • When you have all the tubing coiled in the frame, feed the end through the out-feed hole
  • Use a pair of scissors to trim the zip ties
Drilling holes for the legs

Attaching the Legs

  • Find the center of the 4 x4 board, use a 1/2" spacer to identify the spot where you'll drill a 3/8" hole. Drill the hole completely through the 4 x 4 
  • Connect each leg to the frame with a 3/8" lag bolt
  • You can add a 2 X 4 on each side to prevent the legs from wobbling if necessary
  • Attach a small 2 x 4 in the center of the tubing and paint it black
  • Paint the four legs black
Drilling holes into the cover

Add the Acrylic Top

  • Leaving the protective film on the acrylic sheet, place it on top of the frame
  • Use a plastic drill bit to drill holes through the acrylic sheet 
  • Then, use a regular drill bit to re-drill the holes into the wood
  • Remove the acrylic sheet and vacuum out the inside of the tubing area
  • Remove one side of the protective film from the acrylic sheet and place it back on top of the frame
  • Secure it in place using 1-1/4" deck screws
  • Remove the protective film from the top of the acrylic sheet
  • Attach hose connectors to the in-feed and out-feed of the solar panel heater

Watch the Video

tools needed for copper cutting and soldering

Alternative DIY Solar Water Heater Builds

As we mentioned, there are plenty of options when it comes to building a solar water heating system.

The build method you choose will largely depend on your skill level and requirements. Here are a couple we feel are worth considering:

Copper Panels

If you don't mind soldering and working with copper tubes, then this might be a great alternative method for you.

Watch the Video

Recycled Water Heater

Another option is to ditch the solar panels altogether and heat the water in an old electric water heater tank. Here's what to do:

Watch the Video

Install a DIY Solar Water Heater

After building your solar panel you need to decide how you want to use the hot water it'll generate. You'll be able to easily heat water for a pool, hot tub, outdoor shower or any other scenario where you'll need hot water.

You can even attach it to a tank (such as an old electric water heater) to collect and store your hot water. The tank can be connected to your existing water heater to help lower your overall water heating costs.

We highly recommend contacting a professional if you plan to connect your solar water heater to your home's water heating system. It's important that this is done correctly to not only prevent damage, but also ensure it is safe.

This video shows you how to connect a tank (without solar panels) to a water heater.

Watch the Video

How to Convert an Old Electric Water Heater

If you have an old electric water heater, you can remove the outer shell and insulation, as well as the pipe fittings. While you have the tank stripped down, it's a good idea to flush the inside of the tank to ensure all the sediment has been removed.

Next, paint the tank flat black. This will increase the heat absorption.

Replace the pipe fittings, temperature/pressure relief valve, and the drain. Then seal the joints and connections with silicone, and connect the heater to your solar panel.

Your homemade solar water heater will heat the water as it flows through the panel, and then collect and store the water. The sun will keep the water warm while it's stored in the tank until you need hot water.

Finding The Perfect Location For DIY Solar Water Heater

Positioning Your DIY Solar Water Heater

You'll want to position your solar panel and/or storage tank in a location where it gets the most sunlight.

As a general rule, if you live in the Northern Hemisphere, positioning your system on the Southside of your home will be the most effective. Likewise, if you live in the Southern Hemisphere, your system should be on the Northside.

You'll also want to take into consideration structures (such as fences) and bushes and trees that may cast shade over your solar water heater and will seriously reduce the amount of hot water you'll be able to collect.

Holding a Screw and Screw Driver

Material and Equipment List 

Material List

  • One 4 x 8 Sheet of 1/2" exterior plywood 
  • Four kiln-dried 2 x 4 x 8 (for the frame)
  • Four treated 4 x 4 x 8 (for the legs)
  • Wood glue (we recommend Titebond III)
  • Caulking
  • Pocket hole plugs
  • Exterior Latex Rustoleum - Flat Black
  • 500-foot role of irrigation tubing
  • Zip ties
  • Lag Bolts (4)
  • Acrylic Sheet (1/16" thick)
  • 1-1/4" deck screws
  • Hose connectors

Equipment List

  • Table Saw
  • Skill or miter saw
  • Speed square
  • Clamps
  • Drill
  • Countersink bit
  • Pocket tool jig kit (guiding tool and bit)
  • Impact driver
  • Sander (optional)
  • Tape Measure
  • Scissors
  • Plastic drill bit

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