Introducing the solar pool heater, a low-cost way to heat your pool


Installing a solar-powered swimming pool heater is a great way to not only warm up your pool, making it comfortable to swim in well past swimming season; it helps pool owners save money on heating costs, as well. 

The systems are relatively affordable to install, cost less to operate, and often last longer than traditional gas or electric pool heating systems. They’re also versatile and work with different pool sizes and types - solar pool heaters can be used for both above ground pools and in-ground pools.

In this blog, we’ll explain how pool solar heaters work, how much they cost, and whether or not investing in one is right for you.

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solar panels on the rooftop of a poolhouse

How do solar pool heaters work? 

First, pool water is pumped out from the pool through a filter, then to a solar thermal collector where solar energy heats the water before returning it to the pool. The system also requires a check valve, flow control valve, and a sensor in order to keep the pool temperature in check.

infographic showing all of the components of a solar pool heater

Solar pool heaters utilize a solar thermal collector, check valve, flow control valve, and a sensor in order to produce hot water. 

Most systems can automatically detect the temperature of the water and transfer it to the solar collector where it will heat the water before returning it to the pool. When the water reaches the desired temperature, the flow control valve then diverts the flow from the solar collector directly back to the pool.

In the colder parts of the US and in areas where the pool is used year-round, the solar collector is usually oversized - allowing it to keep heating the pool, even when there are significant drops in temperature.

A solar water heater can also be used in tandem with gas or electric heaters if needed.

What is a solar thermal collector? 

Solar thermal collectors harness the thermal energy from sun exposure. Cool water is pumped through the collectors at the bottom. As the sun heats up the water, it rises to the top where it can then be used to warm the water of pools, as well as buildings and homes.

Glazed vs unglazed solar thermal collectors 

There are two primary types of solar thermal collectors - glazed and unglazed. 

Glazed solar collectors 

Also known as flat-plate solar collectors, glazed solar collectors are encased in glass and are often more complicated in design, as they are built from metals (including copper tubing and aluminum plate) under an iron-tempered glass covering. 

infographic depicting glazed solar collector, also known as flat-plate solar collector

These systems can heat water more efficiently and require less space, which allows them to provide higher levels of heat. While glazed solar collectors are suitable for year-round use, they do cost more than unglazed solar collectors.

Unglazed solar collectors 

These collectors are often made of black plastic or heavy-duty rubber and are ultraviolet (UV) treated to help extend their service life.

infographic depicting unglazed solar collector

Unglazed solar collectors, while typically cheaper, are less effective and limited to warmer climates and pools whose temperatures don’t reach below freezing.

Which size solar collector is right for your home? 

Depending on how many months out of the year you plan to use your pool and how warm you prefer your water to be, the Department of Energy (DOE) recommends the solar collector be between 50% and 100% of the square footage size of the pool’s surface.

For example, if a pool is 15-by-20 feet, it has 300 square feet of surface area. Therefore, the solar collector should be between 150 and 300 square feet in size.

Homeowners looking to keep their pool open throughout the year should consider a solar collector that is the full size of the pool or larger.

For example, a 15-by-30-foot outdoor swimming pool in Florida typically requires a collector that equals 100% of the pool's square footage to accommodate year-round use. This equals 450 square feet of collectors.

In northern California, most people use outdoor pools 6–8 months per year, so they typically size their systems at 60%–70% of the pool's surface area.

How much does it cost to install and operate a solar pool heater? 

All in all, a fully-installed solar pool heater costs between $3,000 and $4,000. However, they pay for themselves in energy savings in as little as 1.5 years in the form of avoided energy costs.

You can also opt to power the pool pump with your solar system, making your blue pool even greener; whereas conventional pool pumps can cost anywhere from $1,000 to upwards of $3,000.

Find out how much you can save on your electric bill by heating your pool with rooftop solar panels

Why you should consider making the switch to a solar pool heater 

Solar pool heating systems are likely to last longer than electric or gas pool heaters, due to the fact that they’re more passive than the other options. Learn more about the difference between passive and active solar heating systems here

The solar pool heater uses only solar power to pump the warm water through the system, effectively using far less energy for water heating, as compared to an electric or gas-powered system.

Electric and gas-powered systems require energy to power the pool pump, filter, and the heating elements of the system. Because it uses solar energy to power all of these components, solar pool heaters cost far less than traditional heating systems. 

A solar powered pool heater effectively pays for itself over the course of 1.5 to 7 years, according to the DOE.

Making the most of your solar pool heater installation 

Taking simple measures, such as utilizing a pool cover to help retain heat, effectively reduces the costs associated with operating a solar powered pool heater even further. Solar pool covers are designed to absorb more thermal energy from the sun and transfer it to the pool surface.

Other possible ways to provide a little extra warmth in the pool include the use of Solar Sun Rings. They float on the surface of a pool and provide small amounts of heating.

Since a solar pool heater requires both electrical and plumbing work, it is recommended that you contact a professional contractor to install the heating systems - especially if you are looking to place the installation on your roof.

Both pool and solar contractors can install a solar powered pool heater, however solar installers will be aware of any local solar rebates and incentives that are available in your area.

How much can you save with solar?
 - Author of Solar Reviews

Chris Meehan

Veteran Solar Technology Journalist

Chris Meehan is a freelance writer for SolarReviews

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