Traditionally, if you wanted to heat the water in your pool, you had to use a gas or electric heater. Just like heating your house, the cost of energy can quickly add up. Electricity is expensive. And if you’re heating your pool in the summer, when you’re also running your air conditioner, your electric bill can skyrocket. The natural gas or propane you need to run a gas heater is also a significant expense that you will be paying every time you heat your water. But there is a third option that costs exactly nothing to run. (Not exactly, but we’ll get to that.) If you’re tired of high gas and electric bills, it’s time to learn how you can save money with a solar pool heater.

What Is a Solar Pool Heater

This may not come as a surprise, but the sun is hot. Very hot. 10,000º Fahrenheit hot at the surface. 93 million miles (or about 8 minutes) later, the heat and light of the sun reach us, here on earth. By the time all that energy gets to us, it shines at about 1,300 Watts per square meter. How much of that becomes surface heat varies greatly depending on many, many factors which we cumulatively call climate or weather. But suffice it to say, the sun provides a lot of energy. Solar pool heaters use that energy, instead of combustion or electrical energy, to heat the water in your pool.

A solar pool heater is, in essence, a very simple, almost entirely mechanical piece of equipment. Water is extracted from your pool by your pool pump. From there, the pump sends the water through a filter. If you have any type of pool heater, the next place the water goes is to the heater. That’s where the magic happens.

In the case of an electric or gas pool heater, the water is heated in the heater and then continues on its journey. If you have a solar pool heater, a valve diverts some of the water from the filter into large solar collection panels installed in a sunny spot around your home. (More on that later.) There, the water follows a winding path through the solar collection panels, and as it does so, it is heated by the sun. Finally, the heated water returns to your pool. The major advantage of the solar heater is that, unlike the electric or gas heater, the power that heats the water is 100% free, clean, and renewable. The only energy costs you have are the electricity to run your pump (but you were already doing that), and the few pennies it costs to run your automatic controller.

Installing a Solar Pool Heater

Installing a solar pool heater is pretty simple. If you want to do it yourself, plan to do it over two days or as a weekend project. If you plan to have someone do it for you, expect to pay around $1,000 for an in-ground pool or about $500 for an above-ground pool. Installing a solar pool heater involves placing the solar collector panels in the right spot, attaching them to their final location, and then running the plumbing to take the water to and from the collector panels.

If you have an in-ground pool, it is also highly recommended that you install an automatic controller. The controller switches a valve on an off to control when water flows through the solar collection panels. Simply set a thermostat on the controller, and the rest is automatic. When there is solar energy coming to the collectors, the controller sends water through them. When the water reaches the desired temperature, the valve closes, and the collectors no longer receive water.

In the hot summer months, you can reverse that process to actually cool your swimming pool. Simply set the controller to run at night. The warm water in your pool will be pumped out of your pool up to collector panels where the cooler night air will cool the water.

How Many Panels Do You Need

How many solar collectors (or panels) you will need depends on the size of your pool, how much you want to heat it, and how much sun you can expect to reach the collectors. If you are only heating your pool spring through fall and you are able to place your panels facing due south in full sunlight, you can get away with as little as 50% of the area of your pool. However, more is always better. We suggest at least 75% of your pool area if you will close your pool when it gets chilly, and 100% if you want to keep it open longer. Panels usually come in two sizes, 4’x10’  and 4’x20’.

Here’s an example of a pool that is 15 ft. x 30 ft. that will use 75% coverage:

15 x 30  = 450 is the surface area of your pool

75% x 450 = 338 is the required surface area of your panels

338 ÷ 40 = 8.45 rounding up, it will take nine 4’x10’ panels to heat your pool

Where to Put The Solar Collectors

The most significant factor in how efficiently your solar pool heater works is the placement of the solar heat collectors. To work properly, the collectors should receive at least 6-8 hours a day of unobstructed sunlight. To get the most sun, it is best to orient them facing south. If they can’t face due south, consider adding more panels to get the full benefit of the sun.

As long as you panels face more or less due south and the sun isn’t blocked during most of the day, it doesn’t matter where they are placed. Many people put them on the roof. The roof is convenient because it is out of the way and likely less obstructed than on the ground. However, you could also install them on a rack in your backyard, as long as that spot gets enough sunlight.

If You Already Have a Pool Heater

If you already have a pool heater and will be replacing it with a solar pool heater, consider keeping the old heater and making it part of your heating system. Direct water from the filter first to the solar heater and then to the gas or electric heater. A solar pool heater won’t work when it is overcast. If the sun doesn’t shine for a couple of days, it could take a couple of days to get your water back up to your desired temperature when the sun comes out. It also won’t work as well in the winter or on cold days in the spring or fall. But with the two systems together, you can maintain a steady water temperature all year round while still significantly reducing your energy costs.

When your solar pool heater is working to capacity, you can shut off your old heater. But when there’s not enough sun to get the water as warm as you’d like, you can switch on your old heater. The solar heater will still preheat the water, and your old heater will need a lot less energy to heat the water the remaining few degrees to your ideal temperature. Think of it like a hybrid gas-electric car. With the two systems working together, you can cut down on energy use while still getting the full functionality of a traditional heater.

If you’re considering installing a solar pool heater, we’d be happy to answer your questions. Just contact us.