So what's the optimal tilt install angle (pitch) for a North facing pool heating collector for the longest pool season?
It's more complex than you think and the results are somewhat surprising. Generally, speaking the optimal tilt for a PV system - if you want maximum sun collection - is as a rule of thumb equal to the latitude, hence for Melbourne with latitude 37.5º, the best first guess at an optimal tilt would be 37.5º (for a more accurate estimate see Jacobson et.al. Solar Energy 169 (2018) 55–66).But does this rule of thumb hold for a pool heating system? Well no, actually it falls over quite spectacularly. What we did was work out the optimal tilt from our previous post on optimal install angles - tilt and azimuth (compass direction) see here, for all 8 Australian state capitals. We then plotted the optimal pool collector tilt vs latitude of the location and compared this to solar PV systems.
Optimal North Facing Solar Pool Collector Tilt (Pitch) Angle vs PV Panels
What the chart clearly shows is that the rule of thumb has an opposite relationship to a PV system, namely for low latitude areas like Darwin (latitude 12.4º) for example, you want a large tilt like 40º. While for high latitude areas like Hobart (latitude 42.8º) you want a low tilt 20-25º. Why?
It's all about the timing of the swimming season and when you need the heating. So for Darwin the pool heating season is May through August, i.e., when the sun is low in the sky so you want a sharp tilt to catch this energy, while in Hobart the heating season is in the peak of summer, i.e., when the sun is high in the sky, so you want a flat pitch install.
So if you're in Darwin and you have a choice to put up PV panels and a solar pool heating system, put the PV on a flat roof and the solar pool heating system on a sharply pitched roof - the opposite if you're in Hobart.
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