Swimming pool solar heating is a usable choice option to keeping your pool warm throughout the year. It relies upon the method of heating water through a sequence of solar panels which are exposed to daylight, and absorb the heat. It isn't primarily not based on photoelectric cells which generate electrical energy from daylight, instead it's a more direct conversion of heat in sunlight to heat in water.
The water is fed through the solar cells by the swimming pool pump. The solar panels can be installed on the roof of your place, or they can essentially be installed at ground zero in a bracket. The roof level panels are out of the way and not taking up any space in your garden, but the water may need a booster pump to help it battle against gravity on the way up. Either way you'll need to angle your solar energy panels so that they face the sun properly for your latitude. In the northwards hemisphere, this implies that your panels meet face to the south. In the southern hemisphere it's the other way round.
Doing this means that you get the maximum efficient assimilation of heat in the coldest months of the year, when you want the energy most of all.
But what happens on really hot days? Does this water continue to heat up until the pool is distressingly hot or dangerously hot? No, the solar system has a thermostatic controller which makes sure the temperature of the pool does not go too high. It might definitely stop freezing, but to get nicely warm water in the wintertime months you may need to help your solar energy panels with a more conventional heater such as a gas powered heater. However, the solar powered system would definitely pay for itself because it is so much cheaper to run than the gas heater, which will only need to be used now and then.
Whichever route you used to heat your pool, you must definitely get a pool cover and use it to keep heat in when the pool is not in use. The bulk of the heat that is lost from the swimming pool system is lost from the outside of the pool itself. Using a cover to preserve the heat can halve your heating bills!
Solar is a nice option to have free heat from the sun for your swimming pool. The only downside is that solar is not sufficient to heat spas. Many people these days have pools and spas, while solar will bring heat and most times plenty enough for the pool, the spa is not going to get actually hot from the solar. Anyway, you don't always need a hot spa and that's fine, still, if you have a pool and a spa you will likely want to have a traditional swimming pool heater so the spa can get to the temperature you're going to want. Adding solar in this case becomes an added expense. Over time, it will pay for itself and you'll have to decide if it's worth adding it from the start.
Inground swimming pools often have solar heating. Especially when it's a pool only. With a pool only, solar is a great option. Still, you can't control heat from the sun like you can a traditional heater. You'll have to take what you can get but if you live in a place with enough sun then you'll have plenty of heat for your swimming pool.
Local swimming pool dealers can usually help with planning for solar. If you're interested in getting a new swimming pool you can have solar from the start but it's also commonly added to existing pools.