Solar Pool Heating – Is This Really Viable?

Swimming is a valuable form of exercise and you can make it more pleasant with a pool heater but this can be expensive. Using free solar energy seems to be a good idea but is this really a practical alternative to a gas or electric pool heater?

Whilst there are more expensive options available, for the typical domestic owner of a small to medium size pool (who doesn’t want to spend a fortune) there are two main options.

  • The rubber matting type
  • The new solar pods type.

The biggest problem with any type of solar heating is that there is no thermostat that you can set and just wait, a few hours (or days), for the pool to get to the desired temperature. With solar heating you are at the mercy of the weather. If the sun shines then the pool will be pleasant but if it decides to stay behind the clouds the pool may be too cold. If it is important to you that the pool water stays at a constant temperature then solar heating (at least as your sole method of heating the pool) is not for you. You will need a back up source of heat and that will come at a cost.

The key point to remember is that the water temperature will always eventually match that in its environment. Given enough time a large mass of water, like your swimming pool, will reach the same temperature as its surroundings. In hot climates this can even lead to the opposite problem – the pool gets too warm. However in most places you will be looking at needing to add some heat to make swimming a good experience.

An issue with solar heaters is that when the sun comes out, and the weather gets warm, the pool will be warm up anyway. Experiments have shown that a solar heater will  add to this and a solar heated pool (with a pool cover) will always to slightly warmer than an unheated pool but not by a great deal. It is inevitable that the pool temperature will drop overnight so if you are wanting to use the pool early in the morning solor heating is not going to be a major benefit. However if your pool is only used when the weather is warm then solar heating may just give your pool the boost of heat needed to make swimming a pleasant experience.

In general, provided you accept the limitations of the climate where you live, solar heating is worth investing in. We would sum up the pros and cons as follows


  • The pool temperature will never be constant
  • The water will cool considerably at night and in a cloudy spell of weather
  • No ideal for early morning use of the pool.


  • The heat you do get is free
  • In practice it is likely that you will mainly use your pool in good weather.