Solar swimming pool heaters are pretty easy to understand.
There's no AC, DC, or electrons to worry about.
The water from your pool is simply pumped through a filter, then through solar energy collectors where the sun heats the water.
Then that nice heated water goes back into the pool.
Heating your pool with the sun is similar to using a solar hot water system in your house except the water is only heated to 80°F instead of 140°F.
A good solar heater for your pool could run you about $800 for a 10x16 foot pool but that money could extend your swimming season by a month in the spring and a month in the fall.
That's a pretty good return on investment when you think about all that extra swimming time.
There are also solar collectors specially designed for above-ground pools.
Do you have limited yard or roof space available?
Check out a panel-free system like the dome-style solar collector made by AquaQuik (I've read mixed reviews of these dome solar heaters, so make sure there's a warranty).
Also, be sure to check out a solar pool cover to ease the burden on your solar collectors.
How many panel collectors will you need?
The rule of thumb is that your total collector surface area should be about half the surface area of your pool. You can find a 4x20 foot collector panel at a pool supply store for about $220.
Most people put the collector panels on the roof where they get lots of sun and people aren't tripping over them.
The only downside to this is that your swimming pool pump will have to work harder to pump the water to the height of the collectors. Check the "head pressure" specs of your pump to see the height it is designed to pump to.
If you're handy and looking to save some money you can also look into making your own solar swimming pool heater. There are plenty of easy to follow plans available.