Solar Heating for Hydrotherapy Pool

[unclefester]

Hi - writing in not so sunny England - I run a canine hydrotherapy pool with a 1500 gallon capacity - the increasing cost of electricity is making me rethink pool heating and I'm considering solar heating as the way forward - I have a south facing roof for mounting the panels so that side of things makes sense but I'm wondering whether a DIY system with a couple of old painted radiators boxed and insulated would be good enough or whether I would be better off with evacuated tubes (operating temperature would be 30 degrees C)

Thanks

[Naptown]

First things first.
If you do not have a solar blanket to put on that pool when not in use get one. This alone will cut the energy use substantially by reducing the evaporative losses on the pool which are about 70% normally and even higher as the temperature goes up.

[unclefester]

Thermal blanket is already used overnight and on quiet days, though I am also thinking of trying to find something closer to a hot tub lid to improve that side of things

[MikeSolar]

I think you should look at using a heat pump. 30C is perfect for your project and it will cut your cost by at least 60%. Solar can be added as well for a further reduction and should be considered the base heating system with the HP as backup. Where are you? I know a few good heat pump people on your side of the pond.