A solar swimming pool heater can add up to four months more swimming time, dependent upon where you live, allowing you to get a lot more out of your pool. Better still, they cost next to nothing to run and according to most manufacturers will pay your back the installation cost within five years. You will need to make a choice about the the type of water collection and heating system you use. This will typically depend on the location constraints of where you intend to place it. It is worth doing some thorough research on your situation as technology advances can make a big difference to the effectiveness of the heating device and efficiency of the system.
On the other hand, if the pool temperature is lower (to your specified temperature), the heated water be sent to the pool.
Dependent upon your location, spring and summer temperatures are between 5 to 7 degrees celsius higher than autumn. It is September and the autumn months through which you are typically hoping to extend your swimming time.