Using Solar Power to Heat a Pool Explained for Beginners

Using Solar Power To Heat A Pool Explained

Many homeowners are switching to renewable energy out of concern for the environment and their wallets. Solar energy is a particularly popular type nowadays. If you have been thinking about using solar power to heat your pool, you might have wondered how the process works and what kinds of equipment are involved.

Solar panels installed in areas of direct sunlight absorb sunlight and convert the heat from the light into the power that fuels your pre-existing pool heater.

You do not have to be an expert in particle physics to understand the basics of how solar power can heat your pool and keep the water nice and warm whenever you feel like taking a dip. The sun’s energy is a convenient resource that can be used in many different ways, but this article will focus on solar-powered pool heating systems.

How Solar Powered Systems Heat a Pool

The main difference between a solar-powered pool heating system and a gas-powered pool heating system is the source of power. In general, the systems work in very similar ways. The power source contributes to a pump that runs the water through the area that generates warmth. The warm water is then pumped out in exchange for the cooler water.

Some pool heating systems can also function as cooling systems if you live in a hot climate and do not want your pool to feel like a bathtub. By running the water at night through the area that solar panels heat during the day, the water loses some of the heat it collected during the day, so you can feel refreshed when you jump in the next morning.

As we will explain below, a solar-powered pool heating system typically includes the following components:

  • The solar panels
  • The pump
  • The flow control valve (automatic or manual)
  • The filter


The solar panels are the parts that actually absorb the sunlight and then generate electricity from that sunlight. We delve into the exact nature of generating electricity from solar power in the section below. The solar panels warm up an area that the water can circulate through and take some of that warmth. These are how the water becomes warm in the first place.

The pump keeps the water always moving throughout the pool. The pump is responsible for getting the water to flow through the solar-heated section, where the water becomes warm and then back out into the main body of the pool. As the warm water flows out, the cool water flows in so that it can also be heated.

The filter is there to collect any kinds of small debris that have fallen into your pool during the day or night. The filter will need to be frequently cleaned if you live in an area where trees might shed their leaves or seeds into the pool or if you often find small animals have drowned in the pool. The pump runs the water through the filter on its way to heat up.

The flow control valve can either be automatic or manual, depending on the system you choose to install. Generally, automated systems include sensors that keep track of your pool’s current temperature. The pump will kick in and start to circulate the water if it falls below a specific temperature or sense when the pool has reached your desired temperature and stop heating.


What your solar panels are made out of depends on your geographic location and when you plan to use the pool. For people who live in milder climates and only want to use their pool during periods when the temperature outside is above freezing, you can use unglazed solar pool collectors. Glazed collectors are more expensive but more robust.

Unglazed solar pool collectors can be made of plastic or heavy-duty rubber. Regardless of which material is used, the pool collector is often given a coat of ultraviolet light inhibitor so that the panels have increased durability and will not degrade over time. However, during a cold spike, you will need to turn the collector off and drain the water back into the pool.

Glazed solar pool collectors include a glass covering, hence the name, on top of copper tubes that are mounted on a plate made of aluminum. These systems make use of transfer fluids and heat exchangers and so are better at collecting solar power even during shorter days. These components make the system more expensive but more effective in the cold.

Some people utilize their glazed solar collectors for other purposes as well. In below-freezing temperatures, even if they do not want to go swimming, they can use the collectors to heat the water in their houses all year without needing to worry about frozen pipes or degrading metal.

Unglazed Solar Pool CollectorsGlazed Solar Pool Collectors
Milder climatesColder climates
Only swimming for part of the yearBetter for swimming all year
Must shut off during cold snapsNever need to turn off
Less expensiveMore expensive

How Warm Does A Solar-Heated Pool Get?

Typically, unglazed solar panels can heat your pool between eight to twelve degrees Fahrenheit higher than your pool would generally get without any heating. For most people, that is more than enough. When the air is warm, and you are ready for a swim, many people prefer a pool with a temperature in the low 80s.

On a hot summer’s day, your pool might naturally be in the low to mid-70s normally, so the addition of solar heating is enough to bring the pool’s temperature up to a comfortable point. Young children and the elderly often prefer a slightly warmer pool, which you might be able to achieve depending on the weather.

For people who live in colder regions of the world and want to be able to swim during the winter, however, you need not despair. Even if you have had a snowy winter, on days when the sun is shining brightly, as long as you keep your panels clear, you can heat the pool to temperatures in the mid to high 70s Fahrenheit with glazed pool collectors.

By using a pool cover at night, you can hold on to the heat that you produced during the day and enable the pool to reach a higher temperature the next day. This temperature will not rise incrementally forever, although it may be helpful, especially during the winter. On a day with cloudy skies, you might be thankful for yesterday’s heat.

How Long Does Solar Heating a Pool Take?

The length of time you need to wait for your pool to heat up depends on where you live, the current weather your area is experiencing, and the last time you heated the pool. Often, the first time you heat the pool for the year will take the longest because the weather is still warming up, and many places experience rain in the springtime.

In a hot climate with no chance of rain, heating the pool with an unglazed solar collector may take a few days when spring rolls around. In a cooler climate, it might take an entire week to warm up. You can then leave the heating on for the remainder of the swimming season or turn it off at night, depending on your preferences.

For glazed solar pool collectors, the time to heat is much shorter. They are much more effective at raising the temperature in colder weather and heating the entire pool quickly. With glazed solar pool collectors, you can heat a medium-sized swimming pool in just a few hours if the sun is shining brightly.

If you use a pool cover to retain the heat from previous days, you will likely also decrease the amount of time it takes to heat the pool for a new day of swimming. Instead of taking an entire day to warm the pool with an unglazed solar pool collector, a pool cover may enable you to do so within a matter of hours so you can swim that very day.

How Much Does a Solar-Powered Pool Heater Cost?

Solar panels themselves can be a costly investment, but the benefits that they provide are numerous. So numerous that the federal government offers up to a 30% tax incentive for households that utilize solar power for the utilities. State and local governments also offer various amounts of tax incentives as well.

Typically, customers find that solar-powered pool heating is much less expensive than other pool heaters like gas. The primary cost comes from initially buying and installing the solar panels that generate the electricity to power your pool heater. Once those panels are in, the annual fees for keeping your pool warm are much lower than gas pool heaters.

If you are only in the market for a solar-powered pool heater and are not interested in using solar power for any other purposes, like powering your house or heating your water indoors, the average consumer will likely spend between $3,000-$4,000. This price will include both buying the components and installing them.

If you ask the manufacturer to include freeze protection, that may increase the cost. Always keep in mind that you should compare the costs of multiple companies to find the best price. However, the cost will depend on a few aspects of your pool that you should examine before contacting suppliers and asking for their expenses, including:

  • How much sunlight your property gets during the year
  • How large your solar pool collector needs to be to encompass the entire pool
  • Whether you need any permits or approvals from a Homeowner’s Association
  • The optimal place to collect sunlight on your property

How Much Sunlight Your Property Gets During the Year

This topic is addressed more fully further down in a later section. Still, if you are considering installing a solar pool collector, you will find that it works best in a location that sees a fair amount of sunlight throughout the year. This specifically refers to your property, so if, for example, you have extensive trees providing shade, this collector may not work as well.

Solar power works by harnessing the energy from direct sunlight. Unfortunately, that has little to do with ambient air temperature. So, even if you live in an area that gets very hot during some seasons or months unless the sun is directly shining on the solar panels, you will not be able to generate enough energy to heat your pool.

Conversely, in an area that does not ever grow to be very warm at any time of the year, your property may still receive enough direct sunlight to allow a solar pool collector to function at its optimal state. Properties with areas that have nothing blocking or shading them work best, and if the property faces south, you are even better situated to use the sun’s rays.

Size of Your Desired Solar Pool Collector

Your contractor will make the appropriate measurements and recommendations when it comes to the exact size of your solar pool collector, but it is good to keep in mind how large your pool is. As you consider the cost of purchasing and installing a solar pool collector, the amount of water that will need to be heated is the main factor.

However, other factors that the contractor will consider in their estimation may include:

  • How many months of the year you plan to use the pool
  • The typical temperatures in your area
  • What temperature you prefer your pool to reach when heated
  • How much unshaded area is present on your property
  • What type of solar pool collector you are buying (i.e., unglazed vs. glazed)
  • Whether you plan to use a pool cover

Usually, the solar pool collector needs to be somewhere between half the size of your pool to the same length as your pool in order to accommodate all of the water. However, if your region is known for very low temperatures during times when you will want to swim, the pool collector may need to be larger to disperse the heat better and absorb the minimal sunlight.

Do not make the mistake of thinking that a warmer climate automatically means that you can have a smaller solar pool collector though. A warmer climate often means that people want to heat their pool and swim every month of the year, which necessitates a larger pool collector. Cooler temperatures often only feature swimming for 6-8 months.

The use of a pool cover is an effective way to reduce your need for a large pool collector because the cover holds the heat in with the water and decreases the chance for the colder air to penetrate the water. You may have a smaller pool collector if you are diligent about using your pool cover whenever you are not swimming.

Permits and Approvals

Whether you need individual permits and approvals depends heavily on where you live and your community’s rules. You will need to look into local regulations and codes to determine whether you need to apply for extra approvals to abide by the local laws.

Additionally, depending on your region, you may need to check and ensure that the company performing the installation has the proper licenses and registrations. If you choose an installation company that does not, you might risk voiding the manufacturer’s warranty on some of the components or the entire solar pool collector system.

Where to Gather Sunlight

Your solar collector can be just about anywhere, as long as it is relatively near the pool itself. Many people choose to put solar panels on their roof since it is an elevated surface that has direct access to the sunlight. Typically, a roof is high enough to avoid the perils of trees blocking the sun, and the panels are out of the way and not taking up space on your property.

There are optimal angles and tilts for a solar collector discussed in sections below, but typically using a flat roof does not impact the amount of energy that you can absorb by any significant margin. A roof is often a convenient place for people with smaller backyards or without the space on their property to accommodate the panels.

However, the roof is not always the ideal place. Your solar panels will need maintenance occasionally, as well as routine cleaning, to continue to function at maximum capacity. It can be a real pain to climb up onto the roof to clean the panels or sweep away any stray leaves or plant matter that might have accumulated up there.

How Solar Power Works for Your Pool

Solar panels are not complicated. On the most basic level, they are absorbing the light from the sun and turning that light into energy. The reason that many people put them on their roofs is that although the panels are long and wide, they do not weigh very much and have no chance of harming your roof tiles.

With more panels comes more energy because the surface area, where the sun hits the panel, is where the power is generated. When the light hits the surface of a solar panel, the process of penetrating the tiny electromagnetic field that covers the solar panels releases energy. That energy is then trapped by the panels and later used to power things.

One of those things is your pool heater. The energy trapped from the sunlight is sent down to a heating area where the cold water from your pool is pumped in. By rushing through the warm spot, the water is then warmed and released back out into the pool. Simultaneously, new water is pushed in to let in the warm and taking out the cold.

The automatic version of the solar pool collector measures your water temperature so that if you need to bring the water in for multiple passes to heat it up to your ideal temperature, the pump will automatically turn on to do so. A manual solar pool collector needs you to turn it on and off when you know you will be swimming.

How Effective Is Solar Power?

There are complicated equations that companies use to calculate the thermal performance rating for any given solar pool collector. However, if you are not someone who wants to bother with megajoules and thermal units, you can also determine solar power’s effectiveness through simpler methods, like considering your geographic location.

Additionally, the more you plan to use your pool, the more cost-effective the solar power will be. If you only go swimming a few times a year, it might not be worth the cost of buying and installing the solar panels. However, if you frequently swim through many months of the year, solar power can end up saving you a lot of money through the years.

Typically, the people who benefit the most financially are those who live in warm climates where they want to swim throughout the entire year. However, for swimmers who live in colder climates, using a high-efficiency solar pool collector can mean extending the swimming season by up to four months.

High-efficiency solar pool collectors cost more than normal solar pool collectors, but what they cost you can be made up by the savings you get in utility bills if you plan to heat your pool regularly or if you live in an area with a lot of direct sunlight. Many people recoup the cost of purchase and installation within a year or two of buying them.

Seasonality and Day Length

As you might guess, it is much more cost-efficient to use a solar pool collector during the summer because the days are longer and the sunlight is more concentrated. For people who live in warmer climates but who only want to use their pool during the summertime, they get the most bang for their buck when it comes to heating their pool.

For solar collectors that are made for pools that will only be used during the summer, they should be tilted at an angle equal to your latitude minus ten or fifteen degrees. When a solar collector is used throughout the entire year, it should be tilted at an angle equal to your latitude in order to maximize the amount of sun it receives.

During the winter, not only is the sun more likely to be obscured by clouds, heavy rain, and possibly snow, but the number of daylight hours is reduced. Even on clear days, the sun simply is not out for as long, and your solar pool collector must work harder to generate enough heat to warm up your entire pool.

Additionally, excessive rain and snow may cover up your solar panels and possibly allow them to freeze overnight when the temperature drops even further. If you live in an area where it snows, you will need to clean your solar panels more regularly to prevent them from being buried underneath a mound of snow for days on end and cracking.

Geographic Location

Some regions of the world have longer days, which provides more opportunity for the solar panels to absorb the sunlight. If you live in an area that is very far north, it may not be as warm, and you may not notice that the weather is warm, but you are still receiving the sun’s light, which is what your solar pool collector needs.

For people living in the northern hemisphere, the best orientation for a solar collector is to face the south. However, being a few degrees to the west or east of true south may not matter as much depending on how the solar collector is tilted. By facing south, the solar collector can absorb as much sunlight as possible to keep your pool nice and toasty.


If you get your solar panels serviced regularly and keep them clean, your solar pool collector can continue to function for between ten to twenty years before you will need to replace parts. The part that requires the most attention is the filter because you will need to empty it frequently so that your water does not clog other parts of the system with leaves and stray plants.

If you have chosen to install a glazed collector, you may need to clean it and keep it properly lubricated in geographical regions with a shortage of natural rainfall. Arid climates can be challenging for the tubing and glass covers to handle, but consulting with the manufacturer or maintenance team will be helpful.

Depending on your state, you may need to find a maintenance company that has the proper licenses and certifications to work on your solar pool collector. If you hire someone without a license, it might be illegal, or you may end up voiding the manufacturer’s warranty on the components or the entire system.

In Summary

For people out there who have been considering using a solar pool collector to heat their pool, you can find all of the information they need in this article. Whether it is because you want to do your part for the environment or you want to save money on your utility bills, solar power is an excellent resource for heating your pool.

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The articles here on are created by Greg, a Tesla vehicle and Tesla solar expert with nearly half a decade of hands-on experience. The information on this site is fact-checked and tested in-person to ensure the best possible level of accuracy.

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