How Solar Thermal Pool Heating Works and Why It Is Worth It

Frustrating to own a pool that sits dormant six months of the year because it is too cold to use it? The price of gas rises. Electric resistance heaters, while inexpensive to install, are expensive to operate. If the heater is turned off, valuable weekend use time in the spring and fall is wasted. Solar thermal pool heating uses the free sunshine that falls on your roof and transfers that solar heat to the pool with little to no ongoing fuel cost.

How Does Solar Thermal Pool Heating Actually Work?

It's simpler than you probably think. There is no separate boiler, no tank of storage, and no antifreeze-filled heat exchanger. The pool water goes through the collectors itself.

Here is the loop itself:

• Existing pool pump is pumping the filtered water up to a ground rack or the roof

• The water is channeled through a matrix of narrow tubes within the flat polymer panels.

• The dark surfaces of the panels are heated by the sun; this heat is directly transferred into the water, which is traveling through the panel.

• The heated water is recycled back into the pool and is a few degrees warmer with every revolution.

• The controller operates the system automatically at only the times when the panel temperature exceeds the pool temperature; thus, it does not cool your water during the nighttime.

Pool panels were developed for pool applications. That means they work well at low temps and high flow rates as opposed to traditional home solar thermal systems, which require a tank, pumps and complicated controls. Pool panels are unglazed and lightweight and are formulated to stand up to pool chemicals for 15-20 years.

What Makes It Different From Gas Or A Standalone Heat Pump?

The primary advantage to gas pool heaters is speed, but the main disadvantage is they burn a dollar a minute from the time you flip the switch. A heat pump will efficiently transfer the heat in the air into the pool; however, they consume a tremendous amount of electricity when air temps are cold.

Solar pool heaters use solar energy for free during the day, produce no flame, no compressor hum, and only the electricity that your pool pump is already consuming. You can generally expect a 3 to 6 degree increase in a pool with properly sized panels on a sunny 75 degree day.

However, this doesn't mean other heaters are outdated. For year-round pool heating, a solar heater is the best choice. You can use it as your main heat source and add backup support when needed.

Why Pool Owners Choose Solar First

The reasons are practical, not technical.

1. Low operating cost. Once installed, the heat is free. Typically most families cut the gas or electric pool heating bill between 70 and 90 percent.

2. Extended swimming season. Normally the swim season only lasts 3 months (in the summer). Most families can now swim 8 or 9 months out of the year, with a pool from April to October. In warmer areas the sun keeps the water warm in the winter without firing up the gas pool heater every day.

3. Quiet, low maintenance. No burners to maintain, no refrigerant loops to service. The annual maintenance of your panels usually only consists of simply rinsing them and checking your valves.

4. Long-lasting. A good quality polymer panel is UV protected and freeze-proof, so you will likely get twice the years of service from your solar panel as you will from a gas heater.

Heater Type	Typical Running Cost	Average Lifespan	Best Role in a Pool System
Solar Pool Panels	Very low, pump only	15 to 20 years	Primary daytime heat
Heat Pump	Moderate, uses electricity	10 to 12 years	Backup during cool or cloudy weather
Gas Heater	High, uses propane or natural gas	5 to 8 years	Fast heating for spas or occasional use

The Smartest Setup Uses Three Parts Together

Your client framework gets it just right! Panels should not play catch-up.

Begin with solar pool heater panels sized between 70-100 percent of the pool's surface area. These will do most of your heating for free!

Install a heat-retaining cover, such as the GeoBubble solar pool cover. The cover performs two functions: it helps with heat loss during the day from evaporation (which is where most pools lose heat overnight), and it actually allows for more heat retention from the sun throughout the day. Users who actually use a cover routinely report about a 30% improvement in heat retention.

Then have a well-functioning pool heat pump (an inverter Arctic unit is a good bet) for secondary heat. You will run it in the morning following a cold night, during a period of a week-long rain spell, or when you need to give the temperature a quick boost before a party. You will run it much less since the solar takes the lion's share.

This system maintains its simplicity and does not involve a convoluted tank storage system, instead centering on actual pool comfort as opposed to some design concept.

Key Takeaway

If the homeowner wants a pool that can be used longer each year but doesn’t need it tied to their home’s solar heating system, they should work with a company that specializes in solar thermal pool heating equipment. Companies like SolarTubs have changed their business model. They recommend solar thermal pool panels to customers first. Then, they suggest using a pool cover or a heat pump as extra support.

This kind of system, once it is sized accurately, will allow for swimming as much as two or four additional months each year with a minimal amount of cost. Therefore, many pool owners who initially buy a SolarTubs system find that this solution is the answer they keep coming back to year after year for pool heating.