Is an undersized solar heater worth it?

[NewWorldViking]

I'm rebuilding my pool shed and I have an opportunity to create a roofline conducive to solar heating for an in-ground pool. The roof would face directly south, full sun and I can angle the roof as I see fit. BUT the roof will only be about 25% of the pool surface, well below recommended size. Now, I do not expect (or want) an 85+ degree pool. That's very distasteful to my Nordic blood, lol. This pool stabilizes at about 64-68 even on 100+ degree days (desert environment with cool nights and a lot of evaporation). Yes, I do swim in that but I'm hoping to bring the water temp up to around the mid to upper 70's and reduce the thermal shock on non-Nordic guests (they say it gives them a heart attack, such drama queens).

Is a 25% solar heating array worth doing?

 

[ajw22]

Can you calculate how many BTU's you expect from the 25% solar heating array?

 

[NewWorldViking]

All the calculator's I've found just calculate how many panels I need. But they all beg the question, needed for what? I don't need or want a giant hot tub. I just want to take the edge off by raising the water temp 5-10 degrees. If a 25% solar array will do that, great. If it will struggle to reach a 5 degree difference I don't see much point in the expense or effort.

 

[Pool_Medic]

Any panels you add will increase the heat. I have several pools with 25% solar coverage and they work fine.