Extending the Swim Season with Solar

Does solar pool heating work in Canada?

Yes, within limits. A pool is a big thermal mass that cools overnight and loses heat mainly by evaporation, so the goal is to add warmth during sunny days and keep it with a cover. Systems work best from late spring to early autumn. Cold nights, wind and shaded yards cut the gains. Expect a warmer, more comfortable pool and a longer season, not tropical water.

The same sunshine that favours the Prairies for PV, covered in Alberta sunshine hours, helps pool collectors, but cold nights remain the main limit.

What collector types are used?

Pool water is low-temperature, so cheap unglazed collectors, usually black polymer panels or tubes, are standard. They do not need glass or insulation because the pool is only a few degrees warmer than the air. The pool pump circulates water through them and a diverter valve or controller sends it to the roof when there is useful sun. Glazed collectors cost more and make sense for year-round or cold-shoulder-season use, as the collector comparison shows.

Other methods are cheaper: a plain cover cuts evaporation loss, and solar rings or blankets give small gains. Heat pumps and gas heaters can be used alongside solar.

Controls matter more than they seem. An automatic controller compares the roof sensor with the pool temperature and only opens the valve to the collectors when the roof is warm enough to add heat, and it can close it again at night so the panels do not cool the pool. Without one, you end up turning valves by hand, and a system that is hard to run tends to be abandoned. Drain-down or winterizing steps are also needed in freezing weather, so ask who does that each autumn.

How big should the system be?

A common rule of thumb sizes unglazed collectors at around half the pool's surface area, more in windy or shaded sites and less with a tight cover. Example with stated assumptions: for a 4.5 by 9 m pool, that is 40.5 square metres of surface, so roughly 20 square metres of collector. The installer should check roof space and orientation, and the principles in the best direction for solar panels guide apply to collectors as well. A south-facing, unshaded roof is the best spot.

What does it cost and what is the payback?

Costs depend on collector area, pipe run to the roof, controls and whether a ground-mounted rack is used. Systems are typically cheaper than household hot-water systems because the parts are simple. Compare against what you now spend heating the pool, since a gas heater can be expensive to run, and ask the installer for the assumptions behind any savings estimate. Prices vary by region and year, so quotes decide. The solar hot water cost guide helps you read what is included.

How is it different from storing heat for winter?

A pool collects and loses heat on the same time scale: days. It cannot carry heat across seasons. Drake Landing in Okotoks solved the seasonal problem differently, collecting summer heat on 800 garage-roof collectors and storing it in 144 boreholes for winter use. The borehole storage page describes that design.

Expect modest results in the first week of June compared with August. Water temperature depends on air temperature, wind, shade and use of a cover, so two neighbours with identical panels can see different numbers. Keeping a thermometer in the pool and noting the readings before and after installation is the plainest way to judge whether the system is earning its keep.

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