How Many Solar Panels To Heat A Swimming Pool?

You’ll generally need between six and 10 solar panels to heat your pool. However, this will be influenced by the surface area of your pool. The surface area of the panels should be 50% to 100% of the surface area size of your swimming pool.

Let’s look at a formula that pool owners can apply when calculating the number of solar panels needed for water heating, and factors that affect the number of panels.

How To Calculate The Number Of Solar Panels Needed To Heat A Pool

As a general rule of thumb, the surface area of the solar panels needs to be a minimum of 50% of the pool surface size. However, it should also not exceed 100% of the pool’s square meterage. In other words, one square metre of the pool equates to one square metre of solar panels. A safe average is to calculate 75% of the pool’s surface area.

Formula

• (Surface area of the pool x percentage of coverage) / size of one solar panel = number of solar panels

Here is a basic, step-by-step example to illustrate.

1. Calculate the pool surface area. Example: If the swimming pool is  5 by 10 sq m, it has a surface area of 50 sq m. Therefore, 5 x 10 = 50 sq m
2. Multiply that number by the percentage you want to cover (50%, 75%, or 100%). This will give you the total surface area of the solar panels required. Example: 50 sq m x 75% = 37.5 sq m.
3. Divide that number by the size of the solar panels. 60-cell panels are typically 1.9 sq m. 72-cell panels are 2 sq m. Example: 1 panel = 2 sq 
4. Now apply the formula. Example: (50 x 0.75) / 2 = approximately 19 solar panels

This calculation will give you a rough estimate of how many solar panels are needed to heat your pool. However, for the most accurate measurement, you need to get a quote from a solar panel specialist.

Factors That Affect How Many Solar Panels Are Needed To Heat Your Pool

Generally speaking, the one-to-one surface ratio between the pool’s surface area and the panels surface area works well. However, there are factors that can further influence how many solar panels you need.

Pool size

There is a huge variety in pool sizes, but the most common sizes for residential swimming pools are approximately:

• Small pool: 3.5×7 sq m with a surface area of 26.7 sq m.
• Medium pool: 5×10 sq m with a surface area of 50 sq m.
• Large pool: 6×12 sq m with a surface area of 72 sq m.

The pool size (width, length, and depth) all play a part in determining how many panels are required. Smaller pools, such as plunge pools and dipping pools, would require fewer panels to heat the water. Larger pools require more.

Climate and weather conditions

Areas with warmer climates will require fewer panels to heat pool water, whereas areas in cold climates will require more panels. Additionally, areas that are often overcast and cold would require more panels than sunny, warm areas. You need to consider how many sunlight hours you receive when making your calculations.

Pool location

Heat retention is directly affected by a pool’s location. Thus, it also affects the solar panels required.

Indoor pools will generally retain heat a lot longer than outdoor pools. The temperature is also easier to maintain as it is not affected by colder outdoor air.

Below-ground pools also maintain heat better as opposed to those above-ground. 

Desired pool temperature

The number of solar panels needed is directly influenced by the desired temperature you want the pool water to be. You need more energy to create more heat.

Insulation

To ensure you get the best heating performance out of your pool heating system, it is recommended that you use pool covers to retain the heat and reduce heat loss. The better the insulation, the fewer solar panels would be needed.

The type of solar pool heating system

Different types of solar pool heating systems have different efficiencies. This directly influences the amount of solar energy captured and converted into heat for your pool. Most systems work with solar collectors, which collect the sun’s energy to heat the pool water. The water is circulated through the solar panels and returned to the swimming pool.

The most common types of solar collectors are either glazed or unglazed collectors. They can have evacuated tubes or flat plates to collect and retain heat. Evacuated tube collectors offer superior heat collection but are typically more expensive than flat plate collectors.

• Unglazed collectors tend to be less efficient in cold climates due to their loss of heat. They are often made from durable plastic or heavy-duty rubber. You will need a larger number of solar panels to compensate for the heat loss and lower efficiency.
• Glazed collectors tend to be the more cost-effective of the two. They are covered with plastic or glass, which traps the heat. This works well in colder climates, such as the UK. Due to their higher efficiency, you will probably need fewer solar panels compared to the unglazed collectors.

Solar swimming pool heaters are a worthy investment, and they should be part of any pool heating system, especially in cooler climates. The right solar pool heaters can supplement solar energy, which is quite useful on cloudy days. This also reduces the strain on the solar panels.

Factors That Affect Solar Panel Efficiency

Solar panels work by collecting energy from the sun’s rays and converting the energy into electricity to power your solar pool heating. There are several factors that affect the efficiency and performance of these panels. 

Shade

If the solar panels are in a shady spot, they may not work efficiently. If they are not running optimally, their heating performance will be lacking. Even partial shading can affect solar panel output. 

Dirt

Dirty solar panels cannot work as efficiently as clean ones. Dirt, dust, or bird droppings hinder the panels’ sun exposure, meaning they cannot collect as much energy as they should. While they generally require little maintenance, you need to regualrly clean your panels. It may also be a good idea to pigeon-proof your solar panels.

Panel degradation

Over time, as the solar panels age, they will lose their ability to collect and convert solar power into energy. To maximise their heating performance, ensure you regularly inspect, clean, and maintain your panels.

Get A Free Solar Heating Quote For Your Pool

If you are still unsure about how many solar panels you need to heat your pool, contact our professionals. At Eco Happy, we provide expert advice and a free solar panel quote based on your pool’s heating needs.

FAQs

Can solar panels heat a swimming pool water all year round?

Yes, solar panels can heat the water of your pool year-round. 

How long does it take for solar panels to heat a pool?

It can take a few hours to raise the temperature a few degrees. The time it takes to reach the desired temperature is determined by several factors, including the size of the pool and the efficiency of the solar pool heating system.

Does the shape of my pool affect how many panels I need to heat the water?

Yes, the shape of the pool does affect the quantity of panels needed. For example, rectangular swimming pools have a larger surface area than kidney-shaped or round pools.

What factors affect how many solar panels to heat a swimming pool indoors?

The factors that affect indoor solar heating include the size of the pool, the desired temperature, the heat pump, and insulation for heat retention. To calculate the number of solar panels for indoor swimming pools, you would still work with the surface area rule and formula.

Final Thoughts

If you are looking to heat your swimming pool water effectively and cost-efficiently, then solar panels are the way to go. To calculate the number of solar panels needed, use your pool’s surface area equal to the surface area of the solar panels. While 50% of the surface area will warm the water, 75% to 100% of the surface area is a good number to work with.