Can I build a solar heater for a pool myself?

Residential Solar Power

We have a swimming pool that we don't use as often as we would like due to the weather. While it isn't exactly cold here it also isn't Southern California weather.

If I could build a pool heater myself that didn't cost me anything to run then it would really help us make better use of the pool and that would make the kids happy.

So is it possible to build your own solar powered pool heater?