I Pool Solar Heating - Help orienting the roof-top solar collector please

AI Thread Summary
In Alamo, California, a homeowner is seeking advice on the optimal roof face for installing pool solar panels, with three options available. Installers have differing opinions: faces #1 and #2 are favored for their afternoon sunlight, while face #3 is suggested for total sunlight throughout the day. Key considerations include the angle of sunlight and its impact on heating efficiency, with some arguing that total light is more important for pool heating than direct angles. The discussion also touches on the temperature of pool water and panel efficiency, questioning whether varying temperatures from different roof faces could lead to inefficiencies. Overall, guidance is sought on thermodynamics and the best approach for maximizing heat transfer to the pool.
seanduffy
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Hello there, Physics forum. I live in Alamo, California and I'm planning to install pool solar. All of the installers have completely different POVs on which face of the roof I should put them, and hoping to get some physics-based advice. Here's the home with the 3 face options (front already has actual solar, so can't use).

Sat view .png


Two installers really like using both faces #1/2 (individually the system might not be large enough), and two others like face #3.

Considerations:
  • Face #1 gets the most direct afternoon sunlight with the best angle of attack
  • Face #2 is about equivalent to face #1 for total sun, but afternoon angle of attached worse
  • Face #3 probably gets the most TOTAL SUNLIGHT for the day, but afternoon sun is less direct. Morning sun is stronger.
I'm getting very different answers on if with pool solar, the angle of the sun relative to the panel matters or doesn't matter like it does with electrical solar. One installer says, all you're doing is heating the collectors so better to optimize for total light. Another says shoot for the most perpendicular afternoon angle of sun to panels.

Any guidance or thoughts on how to approach this problem? Things I need to come up with a point of view on:
  • What are the optimal thermodynamics here and time of day considerations?
    • The pool water itself will be colder in the AM, as will the ambient temp and panel temp? What set up at the end of the day transfers the most heat to the pool water -- e.g. a.) running slightly colder AM water through panels that may heat up a little more quickly on face #3 given the AM light? b.) running slightly warmer afternoon water through warmer afternoon panels (might argue for face #1).
  • Does the angle of attack matter for pool solar (i know it does for electrical) relative to how how the panels get?
  • For the installers that are eyeing using both faces #1/2 does that create a problems / inefficiencies that the panels would be different temperatures throughout the day?
Thanks so much if you're open to spending a minute to help me think through this!

Sean
 
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