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How to Build a DIY Solar Pool Heater for Less Than $100

Matt Giovanisci, Founder and CEO of Swim University By Matt Giovanisci | April 19, 2022

If you’re looking for a cheap, energy-efficient way to heat your pool, making your own DIY solar pool heater is a great option. Not only can you use the sun’s power to heat your water, but the whole project will likely cost less than $100 (which is way cheaper than purchasing solar panels).

Here’s a step-by-step walkthrough on putting together your own DIY solar pool heater. You can watch the video below or keep reading for the complete tutorial.

How a Solar Pool Heater Works

The design of this easy DIY solar pool heater is pretty simple. Colder water is pulled from your pool by a sump pump. That water then enters a coil of black tubing that’s warmed by the sun. Then that heated water returns to your pool.

For this setup, you’ll need a sunny spot off of the ground to set up your solar heater, and you’ll need a few supplies that should cost you less than $100.

Keep in mind that this isn’t nearly as powerful as purchasing an electric water heater or gas water heater, but it’s extremely affordable to run and build. And this type of solar pool heating works best with above ground pools since it’s not powerful enough to heat an inground pool.

Supply List for Homemade Solar Pool Heater

Here are the supplies you’ll need for your DIY pool heater:

DIY Solar Pool Heater Setup

There are a few optional supplies you might want to help your solar pool heater work even better:

How to Build a DIY Solar Pool Heater

  1. Set up your wooden tray. The goal is to keep your irrigation hose mounted on something above the ground so that you can angle toward the sun. A flat sheet of plywood can work totally fine on its own, but framing it by adding wood to the sides will help make it more sturdy.
  2. Line your wooden tray with black fabric, black felt, or black paint. If you want to increase the amount of heat you capture, you’ll want to line your tray with something black at this point. But this is optional and might not be necessary, especially if you have a smaller pool.
  3. Coil up your irrigation hose on your wooden tray. Start coiling your irrigation hose on your wooden tray. Your hose should lie flat on the wood, almost like a record on a turntable. You want to wrap the hose as tightly as you can so you can fit as many loops as possible. Placing a 2×4 on top of the hose as you coil it can be helpful to help brace the hose. It can also help to have a second person to hold things down. Be sure you have the ends of your hose on different sides of your wooden tray. One of these ends is your inlet where cold water is pumped in. The other is your outlet where hot water leaves. They shouldn’t enter and exit at the same point in your pool water.
  4. Wrap your solar heater in the clear tarp. If you want to wrap your solar heater, now’s the time to do that. But again, this is an optional step. You may want to test your heater first and add the clear tarp afterward.
  5. Add your hose attachments. Attach your irrigation hose connector to the end of your hose that will be going into your pool. This is to connect your sump pump. Also, attach your shut-off valve or ball valve to the opposite end of your hose if you’re using one.
  6. Set up your solar heater and attach your sump pump. Place your wooden tray near your pool, off of the ground, and in the sun. Then attach your sump pump to the irrigation hose connector. Submerge the pump in the water and turn on your sump pump. Be sure your hose outlet is in the pool to return the hot water.

By the way, if you want more easy tips and tricks on taking care of your pool, check out our Pool Care Video Course.

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Troubleshooting Your Homemade Solar Pool Heater

If you’re having trouble getting the water to warm up, here’s some troubleshooting tips:

  1. Keep your sump pump and the returning hot water on opposite sides of the pool. Make sure that your pump that’s pulling in cold water is far away from the hose that’s adding in hot water. This will increase the efficiency of your solar heater. And place your pump as low as possible in the pool, since colder water tends to be at the bottom.
  2. Increase your pump speed. The faster your flow rate, the more heat you’ll transfer to the pool water. You might not notice a bigger pool temperature difference, but you’ll actually increase your heat energy transfer. Aim for a 2 to 5-degree difference between the water coming out of your pool and the heated water going back into your pool. A continued, slow temperature rise means you’ve got an efficient heater.
  3. Mount the coils off the ground and maximize the heat from the sun. You don’t want the cold ground to cool off your tubing, so make sure it’s mounted slightly off the ground. And like we mentioned before, you can also line your tray with plack plastic or cover your coils with a clear tarp for more sun absorption and insulation.

Frequently Asked Questions About Solar Pool Heaters

Looking for more help on how to build a solar pool heater for your swimming pool? Here are some common questions and answers.

Can I use a garden hose instead of an irrigation hose?

We don’t recommend using a black garden hose for this DIY project. Garden hoses are made from many different materials and have different diameters than irrigation poly tubing.

How do I make a more powerful solar pool heating system?

If you don’t want to do it yourself, you can purchase solar panels online. It’s an easy way to create a larger version of this DIY solar water heater without having to hack together your own system (it will, however, cost hundreds of dollars more).

Store-bought solar panels usually come with connector kits, allowing you to build a series of solar collectors. You’ll also need plywood, lumber, PVC pipe, a 3-way valve, clamps, and fittings.

Alternatively, you can build and connect multiple DIY pool water heater systems. But no matter what type of solar collection you use, be sure to use a pool cover, like a solar blanket or solar cover, to keep heat from escaping your pool at night.

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Matt Giovanisci, Founder and CEO of Swim University
Matt Giovanisci is the founder of Swim University® and has been in the pool and spa industry since 1993. Since then, his mission is to make pool and hot tub care easy for everyone. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.
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