Solar pool heating

Solar pool heating directs clean water pumped by the filtration system to collector panels exposed to the sun. The water flows through the internal black polyethylene channels, absorbs thermal radiation, and returns warm to the pool through the return inlets. A proven example for above-ground pools is the Gre AR2069 solar heating for above-ground pools, designed with 3.6 m² of collector area and installed directly on the ground or on south-facing tilted supports.

To heat 15,000 liters without incurring recurring operating costs, the right technical solution is to connect a solar thermal collector and an insulating protective cover.

• A solar absorption collector kit compatible with 32 mm or 38 mm pipes.
• A three-way valve with a bypass connection to regulate the flow rate according to daytime solar radiation.
• A filter pump with a minimum power of 0.25 to 0.33 HP to overcome the panel's pressure drop.
• A floating cover for nighttime use that reduces evaporation and retains the heat gained.

This setup raises the temperature by 3 to 5 degrees on sunny days while keeping electricity use strictly limited to the standard filtration schedule.

A properly sized solar system raises the water temperature by 3 to 6 °C compared with an uncovered pool. The exact performance depends directly on daily sunlight, geographic orientation, use of covers overnight, and the assigned water flow rate. Without a protective cover, overnight evaporation can dissipate up to 70% of the energy captured during the day. For residential installations where a consistent temperature increase is desired regardless of the day’s weather conditions, consider alternatives such as the Zodiac RE/LE 3 electric heater - Ref. W40LE03, though this does require electricity from the grid.

The hydraulic head loss caused by height and friction in the solar collectors makes it necessary to check the pump’s flow curve. If the panel is at the same level as the pool, a standard 0.25 HP pump will usually move the water without any technical issues. For elevations above 2 meters or shed roofs, the circuit requires a pump of at least 0.5 HP to 0.75 HP, or an auxiliary booster pump activated by a differential thermostat. Installing a bypass kit is essential to restrict excessive flow, since water that flows too quickly prevents efficient heat transfer inside the collector.

Completely draining the circuit is the only critical preventive maintenance task required to prevent mechanical damage from freezing.

• Disconnect the 32 mm or 38 mm flexible hoses from the primary filtration circuit.
• Open the bottom drain plugs to completely empty the water retained in the internal channels.
• Store the rolled or flat panel in a dry space protected from direct frost.
• Protect the main pool with a suitable cover to prevent water degradation during winter downtime.

Collectors made from black polyethylene stabilized against UV rays can withstand continuous sunlight, but water trapped inside expands when it freezes and can crack the watertight seals.

Solar systems for above-ground and in-ground pools made from polypropylene or high-density polyethylene offer complete resistance to salt and commonly used chemicals. Unlike metal heat exchangers that require special titanium alloys, plastic collectors do not suffer from oxidation, galvanic pitting, or corrosive buildup caused by salt chlorinators. This polymer formulation tolerates high salinity levels and commercial disinfectants without compromising its structural lifespan in 2026. The only mandatory precaution is to install the solar panel before the salt electrolysis cell or chemical dispenser, ensuring that hot water does not concentrate chlorine gas directly against the thermal collector's inner walls.

Installing solar collectors is worthwhile in areas with large nighttime temperature swings, provided you follow the rule of covering the water at sunset. The solar panel provides heat during peak sunlight hours, resulting in considerable temperature increases in the afternoon. However, if the pool remains uncovered at night, the water's surface acts as an inverted radiator, releasing all the accumulated heat into the surrounding cold air. The essential combination for these areas is a daytime solar collector module paired with a nighttime thermal bubble cover, achieving a positive net heat balance that extends the swimming season by several weeks each year.