Of all the environmentally friendly upgrades you can do around the house, pool solar heaters are one of those that makes a lot of sense. One of the main reasons that this makes a sensible choice is pretty obvious - the sun.
Just about all heat and energy on our planet is down to the sun, but solar heating of water is smart because it uses the heat of the sun to directly heat water. The sun is already heating up the ground and the air and so on, all we are doing is harnessing the energy that is already there. It is also really efficient, since there is no conversion necessary like there is in solar cells - the heat goes into the water and makes it hot, end of story.
And it is remarkably straightforward. So much so that there are do it yourself solar heating pool kits on the market that do not need a civil engineering degree to figure out. In fact there is nothing to it - you need some pipes and a pump and er.. that is it.
Well obviously there are some smart improvements that you can make on this idea - solar heating panels have some pretty advanced features to help trap the heat from the sun. This is more than just painting them black (though this can work) - there are additions that stop moisture loss and so on that make the panels even more efficient and allow them to gather heat even on days that do not feel hot.
This is free heat, and installation is not hard nor extremely expensive. One of the best things you can do for your pocket, the planet, and the enjoyment of your pool.