Solar water heaters are comprised of three basic components: collector, tank, and circulator. Of the three components, the collector has the greatest impact on the efficacy of your water heater as it is the part of the system that collects the warmth from the sun and transfers it to the water.

When trying to choose the best solar hot water system for your needs, the first thing you want to decide is whether to employ an active or passive system. While an active system requires a little more equipment--some kind of circulating pump and a few other components--it can provide abundant hot water because the pump pushes the water through the system. An active system also uses more energy because it requires electricity to run the pump.