How Does A Solar Pool Heater Work?

How Does A Solar Pool Heater Work?

If you want to extend your swimming season, you might like the idea of investing in a solar pool heater.

These work wonderfully to heat up your swimming pool by several degrees so that you can enjoy using it for longer periods of time during the year.

What is a solar pool heater, exactly?

A solar pool heater is a system that’s made up of solar panels and pipes. It connects to your swimming pool pump so that it can increase the temperature of your pool’s water.

There are some important things to know about solar pool heaters and how they work.

So, let’s explore solar pool heaters in greater detail and answer some questions you might have about them if you’re interested in investing in them.

How Does A Solar Pool Heater Work?

A solar pool heater makes use of the following components:

  • A solar collector. This is the part that enables the absorption of heat to warm the water, and it’s basically a name that refers to the solar panels in the solar pool heater system.
  • Filter. This removes dirt and debris from the pool water before it enters the collector.
  • Pump. This is your pool pump that will ensure water can circulate through the collector and filter.
  • Flow control valve. This valve can either be manual or automatic, and it pushes water through the system’s solar collector.

How a solar heater works is that it uses the swimming pool pump to divert pool water into the solar collector. Here, the water gets heated up.

When the suitable temperature is achieved, the pool water is pumped back into the swimming pool.

The system makes use of an automatic control valve so that the water temperature and temperature of the solar collectors can be monitored.

The great thing about solar pool heaters is that they’re completely automatic.

You don’t have to do anything once you’ve installed them, other than setting the automation system or time clock on your pool pump to run during the day and setting the solar pool heating system’s automatic temperature indicator to the temp you want it to produce.

Then, sensors in the system will monitor the temperature of the solar collectors and the pool’s temperature.

When the solar collector temp reaches the point of being a few degrees hotter than the water in your pool, it will divert that water through the collectors so that they can be warmed up in order to warm up your swimming pool water to make swimming in it much more pleasant.

What Are The Types Of Solar Pool Heaters? Hot Water Heating System

There are four main types of solar pool heater systems that you should know about so that you can find the one that will suit your needs the best. Let’s take a look at each of them in a bit more detail.

Evacuated Tube Collectors (ETCs)

These systems are most suitable for large, indoor pools. How they work is that they have vacuum tubes that absorb the sun’s rays.

This heat is then sent to a circulating antifreeze solution, before being transferred into the pool through a heat exchanger.

These ETC systems are efficient and can work well in areas that have below freezing temperatures.

However, these systems can cost thousands of dollars when used to heat up large swimming pools and they do have complicated installations.

They’re also heavy, so if they’re going to be put on the roof, homeowners might need to have a building permit for them.

Polymer Systems

These systems make use of polymer substances, such as rubber, PVC, and polypropylene.

You can find these systems in coil or mat designs, and they’re used for above-ground pools that are smaller in size.

Polymer pool heating systems tend to cost less than other heaters, they’re easier to install so they’re perfect for the DIY homeowner, and many of them can be mounted to the ground in close proximity to the pool.

That said, it’s important to bear in mind that they might not be adequate for larger pools that have higher heating requirements and many of them won’t be able to withstand very low temperatures.

You’ll find that some need to be disconnected and drained during the wintertime otherwise they risk becoming damaged.

Flat Plate Collectors

Solar Heating System

As its name suggests, a flat plate collector makes use of a “plate,” which is basically a sheet of aluminum or copper, that’s painted black to better absorb the sun.

This system makes use of tubes that carry liquid through the plate so that the sun’s rays can be absorbed better.

There are two types of flat plate collectors: glazed and unglazed.

  • Glazed flat plate collectors are installed inside a box that’s covered by a sheet of glass. These are usually used to keep indoor swimming pools warm.
  • Unglazed flat plate collectors are said to be better suited for heating outdoor pools during the warmer months.

People tend to choose flat plate collectors because they’re budget-friendly, but the unglazed varieties can’t withstand very cold temperatures which means that they will need to be disconnected during the winter.

Integral Collector Storage (ICS)

Integral Collector Storage heating systems sound complicated, but they’re not really!

They actually work in a similar way to flat plate systems. They make use of hot water storage tanks and collector tubes, both of which are housed in an insulated box.

ICS pool heaters are beneficial because they can actually be made in the home, as Alternative Energy Tutorials explains.

This type of heater is great because it’s easy to install and reliable. However, like some other heater types it does require drainage during the cold seasons.

In addition, ICS heating systems can be heavy, so they will need to be supported by strong roof structures to prevent damage.

Are Solar Pool Heaters Safe?

Family in Swimming Pool

One of the biggest concerns you might have when using a solar heater for your pool is if it’s safe.

The good news is that solar pool heaters are much safer when compared to other heaters that can be used to heat up your pool, such as gas heaters.

For example, they don’t produce toxic and harmful emissions that are a worrying concern with gas heaters.

Solar pool heaters are also more convenient to use than heat pumps as the latter require the use of electricity.

Heat pumps make use of elements such as compressors and motors, so maintaining these systems can end up being costly over time.

With solar heaters, you don’t have to worry about maintenance and you don’t have to incur electricity costs.

Since a solar pool heating system makes use of the natural sun’s rays, it makes use of a renewable energy source that’s completely safe!

That said, you need to be careful when installing your solar pool heater to ensure that you don’t compromise its safety.

For example, if you’re installing your system on the roof, you need to be sure that the roof will be able to support the weight and you need to check if you need a building permit beforehand.

How Long Does A Solar Pool Heater Take To Work?

Swimming Pool Steam

One of the important things to bear in mind when it comes to solar pool heaters is that they won’t work immediately to warm up your pool.

Some heaters will take between three to five days to provide you with warmer water.

You can sometimes shorten this amount of time by covering your pool as this will help to maintain its heat. However, consider the climate of your region.

Of course, if you live in a colder climate where the air temperature is low, this will affect the time it will take for your solar pool heater to work.

Another thing you could do to help to slightly speed up how quickly your pool warms up is to ensure you pay attention to the type of roof construction you have in your home if you want to mount the solar heating system onto it.

For example, metal roofs conduct heat better than slate or tile roofs. On the other hand, dark roofs will absorb more heat than light roofs.

When it comes to water temperature, a misconception that some people have about these heaters is that they can make your water extremely warm.

However, it’s worth bearing in mind that solar-heated pools can achieve temperatures that are between eight to 12 degrees warmer than unheated pools within the same region.

They also tend to lose their heat when it’s cold and at night, which is why the use of a pool cover can help the pool to retain its heat.

Can You Use Your Solar Pool Heater All Year Round?

Roof Solar Pool Heaters

Purchasing a solar pool heating system will make you want to use it all year round so that you can swim no matter what the season, but is this something that you can actually do?

For starters, it’s important to understand that many types of solar pool heaters need to be disconnected and drained during the cold season.

This will prevent them from getting damaged as they cannot withstand icy temperatures.

If, however, you live in a warm region where your solar heating system will be able to receive a lot of sun regularly throughout the year, this makes all-round solar heater use much more viable for you.

And of course, if your solar heater system doesn’t need to be disconnected during the winter because you don’t experience very cold winter seasons or it’s recommended for use throughout the year without needing to be drained (always check with the manufacturer!), then you can enjoy it whenever you like. 

On the other hand, if you live in an area that gets very cold during the winter, it’s a good idea to winterize your solar pool heater, which basically involves draining it so that water can’t collect in the pipes and cause them to burst. Here’s how to do it.

  • Turn off the circulating system.
  • Let the solar collectors and piping drain properly.
  • You should isolate your collectors with a ball valve in their feed line as well as a check valve in their return line.
  • Make sure you’ve switched your solar control to the bypass position.

Related Questions

How much does a solar pool heater cost?

There are many types of solar pool heating systems available and they don’t have to cost a lot of money. You can find ones for less than $200.

You can learn more about the best solar pool heaters by reading “Best Solar Pool Heater: Cheap And Easy Way To Heat Up Your Pool.

What are some benefits of investing in a pool cover?

Pool covers maintain water temperature, prevent water evaporation, and prevent debris from entering the pool, while also blocking some UV rays that make contact with the water and degrade the chlorine in it. This means you can use less chlorine in your pool.


If you want to make the most of your swimming pool, even when temperatures aren’t that great, the use of a solar pool heater can be the perfect solution to help you extend your swimming days in the year.

How wonderful to be able to make the most of your pool instead of being forced out of it because the water’s just too cold!

Although solar pool heaters have many benefits, as we’ve seen in this article, there are some important things to know about them.

Once you know what to expect from them and how they work, you’ll be in a better position to make them work for you.

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