May 20, 2023

3 Ways to Build a DIY Solar Pool Heater

Want to heat your pool using solar power? You don't need to buy a commercial system when you can build your own.

Nothing beats a refreshing dip in a warm pool on a cool day. Although a pool heater won't make your swimming pool feel like a Jacuzzi, it can make it more comfortable to swim in and a more pleasant location to spend cool summer evenings.

A solar heater is also affordable, convenient, and easy to operate. Building one yourself further lowers the cost involved and makes it much cheaper.

A pool heater drains the pool, transports the water to a storage tank, and then refills the pool with hot water. Even if it's chilly outside, your pool will always be a pleasant temperature thanks to the alternating flow of cold and warm water. A solar pool heater is also an eco-friendly way to heat your pool, as it runs on the renewable energy of sunlight.

Most solar pool heaters work with a solar collector, a filter, a pump, and a flow control valve. Water from the pool is circulated through the filter and heated in the collector before being returned to the pool. Generally, solar-powered water heaters are less powerful than electric and gas heaters, but they are cheap and easy to build.

Solar power could be doing much more in your home than heating your swimming pool. We've outlined some of the best solar-powered gadgets you could be using in your home.

There are three main approaches to building a working solar pool heater, based on the type of solar collector: flat plate collector, evacuated tube collector, and batch collector.

This method is easily the most popular way of building a solar pool heater. The underlying idea is simple: a dark, flat surface, usually a copper or aluminum sheet, is heated using sunlight and this energy is transferred to the pool to increase its temperature. This working principle provides several advantages such as affordability, ease of installation, and low maintenance.

Flat plate collectors are usually installed facing the equator. Insulation is added to the bottom and sides of the sheet to minimize heat losses. Here is an example project that uses this approach to building a solar pool heater:

User Bnaiver built a heater for his above-ground pool to maintain a comfortable temperature in the spring and fall. The tools and equipment required for this project are cheap and can be found at Home Depot for less than $100. It uses a 4x4 piece of plywood, a 200-foot long and half-inch diameter vinyl irrigation hose, UV-resistant zip-ties to fasten the hose to the plywood, a valve assembly made up of a series of valves and "Y" adapters, and an outdoor, mechanical timer.

The valve assembly serves the purpose of routing water into the heater and then back into the pool. It also makes it possible for the heater's supply and outflow to be cut out when it is no longer needed.

Measuring using an infrared thermometer, Bnaiver was able to get a reading of 99℉ from the pool. By following the Instructables guide, you should be able to build your own well-working solar pool heater in less than a day's work.

If you're interested in building something more large-scale than a solar water heater, we have listed the components you need to build an off-grid solar power system.

An evacuated tube collector is a solar heating system with a series of glass tubes containing a copper rod or pipe. The air within these tubes is removed to create a vacuum. Also, aluminum nitrate or titanium nitride oxide is applied to the inside of the inner glass tube to maximize sunlight absorption.

Evacuated tube collectors are usually more efficient than flat-plate solar collectors. The vacuum space between the inner and outer glass tubes provides insulation and allows the tubes to retain heat energy with minimal losses. This allows them to perform consistently well.

Evacuated tube collectors, however, tend to be more expensive. An evacuated tube collector can cost as much as 20-40% more than a flat plate collector. They do require less maintenance and can serve you for years after installation. While there is usually some variation in the specifics of how evacuated tube solar water heaters are built, the core concepts remain the same.

This YouTube tutorial by Pete Stothers walks you through how to build your very own evacuated tube solar pool heater. It uses a vacuum tube array (with 12 tubes) and a 12 ~ 24VDC circulating pump. As mentioned earlier, evacuated tube collectors are quite expensive, and you can expect to spend as much as $400 on this project. Here is the second part of the tutorial.

This project can be automated with Home Assistant to monitor the temperature from time to time and regulate the pump flow rate. As Pete mentioned, this DIY project may be much better suited for pools with a smaller surface area such as a hot tub or a backyard spool.

This is the least popular type of solar collector. It is also less efficient and takes up much more space, compared to other collectors. However, the mode of operation is simple enough, and it requires much less maintenance.

Batch collectors are a kind of integral collector storage (ICS) system, which means that the tank and the solar collector are combined into a single unit. This removes the need for pumps and controls in the system.

A glass-plated, insulated box allows sunlight to heat a dark-tinted water tank, which absorbs the heat. The water is heated more efficiently thanks to a metal coil around the tank's exterior, sucking in heat and dispersing it throughout the tank's interior.

Most batch collectors house their water storage tank inside a glass or plastic-enclosed insulating box. For use as a batch collector, all you need is an old, regular water heater tank. Because of its insulated walls, the water storage tank loses less heat to the outside air, and its glass roof lets in solar energy to warm the water.

You can build your own batch collector by following this Instructables guide by Ganesh Ruskin. He uses as many recycled materials as possible in building his batch collector. According to Ganesh himself, this Instructable is a bit rough around the edges, but the main steps are well-detailed, and you should be able to get the gist of what is being described.

Some of the tools and equipment you will need are an old water heater tank, two sheets of plywood, a glass patio door, two lengths of copper and steel pipes, drywall screws, steel plugs, Teflon pipe tape, and primer.

Using a solar pool heater is an environmentally responsible way to keep your pool warm. DIY solar pool heaters are possible to build, even though there are numerous commercially marketed solar pool heaters to choose from online. They take a short time to construct and cost significantly less than commercial options.

Tomisin is a staff writer at MUO with a penchant for breaking down complex topics into easily digestible bits. He first started writing reviews of phones and gadgets in 2016 and loves reading spec sheets and tinkering with new technology.Currently, he writes about DIY tech for MakeUseOf and looks forward to expanding his horizons.