The type you'll need depends on your climate and how you intend to use the collector.

In most solar heating systems, pool water is pumped through the filter and then through the solar panels, where it is heated before it is returned to the pool. In hot climates, the panels can also be used to cool the pool during peak summer months by circulating the water through the collectors at night using them as radiators. There are three main types of solar collectors, plastic mat, glazed panels and coiled tube.

This type of panel is the most expensive, and consists of a strong frame, usually aluminium, that contains an insulating back panel, an adsorbsion panel again often aluminium that has a heat transfer pipe soldeed to it that the water runs through, and a glass panel over the top to stop air movement from cooling the collector panel.

Unglazed collectors don't include a glass covering. They are generally made of heavy-duty rubber or plastic treated with an ultraviolet (UV) light inhibitor to extend the life of the mats. Because of their inexpensive parts and simple design, unglazed collectors are usually less expensive than glazed collectors.

Some systems include sensors and an automatic or manual valve to divert water through the collector when the collector temperature is sufficiently greater than the pool temperature. When the collector temperature is similar to the pool temperature, filtered water simply bypasses the collector and is returned to the pool

These unglazed systems can even work for indoor pools in cold climates if the system is designed to drain back to the pool when not in use. Even if you have to shut the system down during cold weather, unglazed collectors may be more cost effective than installing a more expensive glazed collector system.