Hi SadClown,
Are you referring to the solar collectors, small black tubes where the water flows through them and collects the heat/energy?
Best addition we ever added to the pool. It was always too cool to enjoy. Kids would always complain.
They are commonly installed on angled rooves (or flats rooves).
I have these panels heating up my pool.
During our summer right now we have air temps 22c-30c and night time temps of 11-20c
We found having a cover on the pool was essential to keep in the heat gained during the day.
My pool at the moment sits at 33-34c in the morning 8am and gets up to 36c by late afternoon!! Too hot for some but it's like a big spa.
We have enough panels to equal the surface area of the pool. Situated on a pergola.
But I plan to move them up to the roof 2 stories up about 6.5 metres. Not too worried about the pump height as they say as the water falls back down the outlet it sucks the water down and reduces the height needed. We'll see.
But yes they work very well running 8 hours a day during sunny days.
I installed them all myself but was easy due to the location. I imagine a high angled roof will be more difficult and require help. Really they are simple to install, just extra plumbing needed and the panels themselves are quite cheap.