Pool Heater or Solar Covers?
You probably understand how much heat a solar pool heating system can add to a pool (with or without a pool cover), and how much heat a pool cover can add to a pool (with or without a solar pool heating system).
You also have possibly figured out the synergistic effect between a solar heater and a pool cover and how much heat a solar pool heater used with a pool cover can add to a whole pool.
In this article, we want further to explore this synergistic implication from a slightly different viewpoint.
We ask the question: how much solar collector coverage alone do we require to get the same water temperature as a swimming pool that uses a solar pool heater (with 50% coverage) and a bubble pool cover at the same time.
All calculations were done using our new heat loading simulator (validated against the heat loading standards AS 3634-1989 and ISO TR 12596 1995 here). When we talk about solar pool heater coverage here, we are speaking of a standard traditional 8 tube, i.e., well-spaced PVCu tube/mat/strip system. We use an ON time for the transparent bubble cover of 87.5% of the time, which is more realistic than 100%, which infers the pool is never used.
Solar Pool Cover + Solar Heater vs. Solar Pool Heater ONLY
A solar pool heating system requires anywhere from 70% to 100% coverage to change a transparent bubble style solar pool cover. Now, let's add a mere 50% solar heater coverage to the swimming pool using the pool cover and work out what new solar heater coverage you want to get the same water temperature from solar heating ONLY. Since we're adding a mere 50% solar heating, you'd be forgiven in thinking that as a first guess, the needed solar coverage for the solar ONLY pool would be the above, i.e., 70% to 100% + another 50% correct? well wrong, by far...
... since the actual answer is we need all the coverage from the first table + another 100% solar coverage, i.e., we'd require twice the amount. So Darwin, for instance, adding a mere 50% solar pool heating system coverage with a pool cover, is equal to a whopping 200% solar pool heating coverage alone. The heating input value of 50% coverage solar - when covered using a pool cover translates into 100% coverage solar when uncovered. Why? Since a pool cover substantially decreases the heat loss equation for a pool and traps the gains from a solar pool heating system.
This illustration shows why even a 50% coverage solar pool heating system is worth it, but only when used WITH a solar pool cover.
Again, with such plain outcomes, we can't stress this enough; if you have a solar pool heating system and you're not using a solar pool cover, at least in the shoulder months, you're certainly missing out on some amazing pool temperature gains.
It's vital to stress we are not advocating 50% solar pool heater coverage; this is just an example to demonstrate the power of combining solar heating + pool cover - solar pool heaters should be sized correctly to provide reasonable results during swimming season months. Nevertheless, it shows if you're not going to be using a solar blanket during shoulder months, be prepared to stump up much more for a much larger solar coverage collector array which will still not provide you anywhere near as good a result as if you were to combine solar + cover.
Do you want to know how well a solar pool heating system will work for a precise set of conditions? Head over to our professionals and have a play with it 🙂
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