A Comprehensive Guide to Swimming Pool Solar Water Heaters

Swimming pools can be a great source of enjoyment and relaxation, especially during the warm summer months.

However, heating a pool can be expensive, and traditional methods such as gas or electric heating can be both costly and harmful to the environment.

One alternative solution that has gained popularity in recent years is swimming pool solar water heaters. By harnessing the power of the sun, these systems provide an eco-friendly and cost-effective way to heat your pool.

In this article, we will explore the basics of swimming pool solar water heaters, their components, advantages, and provide tips on buying and building them.

Additionally, we will discuss ways to save on solar pool water heating costs, so you can enjoy your pool without breaking the bank.

Pool solar water heaters: Things to look for

• Basics
• Advantages
• Components
• Sizing
• Costs
• How to save
• Examples
• FAQ

Solar pool heating: Basics

The solar pool heating system is an excellent option for extending the swimming season, as it utilizes free solar energy to increase the pool water temperature. The system can take advantage of both direct and diffuse solar radiation, making it suitable for use in a variety of locations, not just in southern regions.

It's important to note that an unheated pool will only have a temperature slightly higher than the outdoor temperature, particularly in warmer southern regions.

To ensure that the swimming pool solar water heater provides the desired temperature, it must be appropriately sized. If not, a backup boiler will need to be used.

The most popular type of pool solar heating system uses black polypropylene (PP) plastic solar panel that are either rigid or contain individual pipes. These panels are typically roof-mounted and only contain water when it is circulating through them. This is known as the Drainback system, similar to those used in domestic solar water heating. This design is helpful in the wintertime, as it reduces the likelihood of water freezing inside the solar panel and pipes.

The system uses a water pump and filter to circulate and filter the water, removing any impurities.

Advantages

Solar heating is a natural, environmentally-friendly, and cost-effective way to heat a pool. It has no ongoing running costs and requires very little maintenance.

Solar heating systems can increase the temperature of pool water by up to 50°F, depending on various factors such as the location of the installation, pool size and panel area, orientation, color, roof construction, climate, and more.

One of the main advantages of solar water heaters for pools is that they require a lower temperature than those used for domestic hot water production, and they do not require a separate storage tank. This helps homeowners to extend their swimming season while using renewable, free energy without any flames, gas, or venting, making them an eco-friendly choice.

Here are other reasons why to buy and install a swimming pool solar water heater system:

• Low initial cost
• Low annual operating costs
• Easy to install
• Solar pool heating systems are efficient and durable
• Maintenance-free systems
• Faster payback
• Long lifespan

Parts

The main components of the swimming pool solar water heater system are:

• Solar collectors
• Pump
• Filter
• Controllers (i.e., to compare incoming and outgoing water temperature).
• Fittings
• Valves

Solar collectors

The pool solar collector is a crucial component of any heating system, as it is where the sun heats the panels and water inside the tubes. Without a properly functioning solar collector, the heating system would not be able to effectively harness the power of the sun to heat the pool water.

Unglazed type

If the solar panel is made of plastic and rubber without a glass coating, it is called an unglazed solar panel, also known as the soft type. This type of solar collector looks like a rubber mat with tubes that carry water. Due to its flexibility, it can be installed virtually anywhere, including uneven surfaces. Unglazed solar panels are recommended for use in areas with warmer climates. However, in regions with colder weather, they can also be used, but only as the Drainback system, where water is removed when it is cold.

Soft solar collectors are usually roof-mounted or placed close to the ground, and they are designed to heat large amounts of water to relatively low temperatures, which range from 80 to 90 F. This is possible due to the use of polypropylene, a cheap material that makes pool solar water heaters affordable. The downside to the unglazed setup is that the limited operating temperature means that it cannot produce any heat during the winter months.

The standard sizes for pool collectors are 4 feet wide and 8, 10, and 12 feet in length. The top and bottom tubes are called header tubes, which are typically 1.5" or 2" in size, connected with risers that are 1/4" in diameter. The solar panel is connected to PVC pipes through the headers using rubber couplings and hose metal clamps.

The glazed type, also known as the hard type, comes with an iron-tempered glass coating, an aluminum plate, and copper tubing running through it. The typical setup includes a series of several flat black panels, and more units can be added if a larger area is required. Glazed solar collectors are more efficient than unglazed systems, and they can be used throughout the year.

Circulation pumps

Circulation pumps play a crucial role in a solar pool water heating system as they are responsible for circulating water from the pool, passing it through the filter and then pushing it up to the solar collectors. Once the water is heated by the sun, it is then circulated back to the pool, thus raising the overall temperature. Without these pumps, the system wouldn't be able to operate effectively.

Filtration system

The pool water is transferred by the pump to the solar panels, where it is heated by solar radiation, and then returned to the pool. However, before the water reaches the solar collector, it must first pass through the filter to remove debris and ensure clean water. On its way back to the pool, it may also pass through the backup heater and chlorinator, if they are installed.

It is important to note that in the Drainback system, which was previously mentioned, the water from the solar collectors will drain back down into the pool when the pump is turned off. This is an essential feature of the system to prevent freezing or overheating of the collector during periods of inactivity.

Automation

Some systems can be automated. They can use sensors and valves to direct water through the collectors or bypass if heating is not needed.

Popular solar pool heater kits

Building or installing a solar water heater for your swimming pool can be easy if you have experience in plumbing and electrical wiring. By purchasing a solar water heater kit, the installation process is similar to putting together a puzzle. Simply use glue and hose clamps to assemble the system.

Sizing tips

How will you determine the size of a solar panel?

According to experts, the total area of the panel should cover at least 50% of the pool's surface area. For example, if the pool area is 800 sq.ft., the collector should be at least 400 sq. ft. This rough calculation assumes the southern, warmer regions (such as Florida and Texas), if the panel is properly oriented, and if there are no shaded parts in the pool. Otherwise, you have to increase the exposed area of the solar panel.

Use the following formulas to calculate the area of the pool:

Rectangular shape: LxW (L-length, W-width). If the pool is 5'x10', the pool area is 50 sq.ft.

Round shape: 3.14xRxR (R=D/2, where D is pool diameter, R-stands for radius). If the pool is 24 ft., the area is 3.14x12x12=452 sq.ft.

Other factors that should be considered when selecting the panel size:

• Desired pool water temperature
• Direct sun exposure
• Wind exposure
• Different weather conditions
• Using a solar blanket
• Using sensor, valves, and controllers

By using electronics, the system becomes automatic, which increases performance and efficiency. For example, during colder weather, water is not heated, and energy losses are prevented.

Install the solar collectors to face south and tilted at an angle equal to the latitude of the pool's location minus 15 degrees (for summer). The best conditions include a south direction and receiving an average of 6 hours of direct sun per day. Remember that more panels should be added for regions with fewer sunny days to provide the same results.

Costs

To buy a DIY solar water heater kit, size of 300-400 sq. ft., expect to pay from $1500 to $2500 depending on the complexity of your system and the pool size.

But if you want a professional to install it for you, it will cost you double. Warranty from the manufacturer is typically between 10 and 15 years, depending on the quality of the UV screening materials (inhibitors). The predicted payback period is usually between 2 and 7 years.

Tips for saving

Most of the heat loss from a swimming pool, which is over 70%, is caused by water evaporation from the surface. Warm water evaporates more rapidly than cool water. To reduce heat loss due to evaporation, it is recommended to buy a good quality pool cover.

Heat loss is directly proportional to wind velocities, pool temperature, humidity, and air temperature. The most important factor to consider when installing a swimming pool is to have it in a sunny spot, as over 75% of the solar energy is absorbed by the pool water.

It's crucial to properly size your swimming pool solar water heater to minimize heat loss and maximize heat gain. Take into account the location of the swimming pool, shading, wind exposure, and if the panel is oriented towards the south.

Homemade project examples

Andy made this DIY solar pool heater from 100 ft. coils of half-inch plastic pipe for the pool size 30 feet x 12 feet x 4 feet average depth and 11,000 gallons. Solar panels are installed on the roof, and due to the roof layout, they are facing east. This panel was built 5 years ago, and the cost to build was around $300 for tubing and PVC, but the framing materials came from scrap...

Another simple homemade pool solar water heater made by Fraser is located somewhere in Spain. He built the heater for 70 Euros for the pool size of 60 m3 and 1 m3 insulated hot tub while keeping the temperature of 35 C year-round... more

Check out this guide on how to build a solar pool water heater from Instructables.

Summary

Solar pool heaters are an excellent option for reducing energy costs while enjoying a warm swimming pool.

Good-quality solar pool heaters are made of high-quality and durable materials, which make them versatile and easy to install on different objects such as roofs, sheds, ground, and racks.

They also have an extended warranty and require low maintenance, resulting in low operational costs.

Many reviews suggest that solar pool heaters are dependable, simple to install, and economical, even though the upfront price might be higher than other heating systems.

If you decide to install a solar pool heater, it is recommended to hire a licensed professional for the installation. However, for a handyman, a DIY installation kit is also available and can be installed with ease.

With these benefits, a solar pool heater is an excellent investment that can provide a return on investment in just a few years.

FAQ

How long does it take for a solar pool heater to pay for itself?

The payback period for a solar pool heater typically ranges from 2 to 7 years, depending on the cost of installation, size of the system, and energy savings achieved.

How long does a solar pool heater last?

A good-quality solar pool heater can last up to 15 years, depending on the materials used and maintenance provided. Most manufacturers offer warranties of 10-15 years.

How effective are solar pool heaters?

Solar pool heaters can be very effective, especially in sunny regions with minimal shading. They can raise the pool temperature by 10-15 degrees Fahrenheit, providing a comfortable swimming experience throughout the season.