The advancement in solar thermal heating has resulted in cost effective solar heaters that are almost 94% efficient. This has caused new applications such as solar hot tub heating and much more cost effective hot water heating systems for both pools and homes. Soar Thermal Heating systems compared to Solar Photo Voltiac, are nearly 500% more efficient. As an example the most efficient PV system on the market is only about 16% and cost per Kw is nearly double that of solar thermal.
When looking at solar water heating for pools or spas you should consider the following 3 topics before you make your solar investment:
1. Open Loop or Closed Loop solar system
2. Control valve to shut off solar system at night
3. Location Location Location of solar collectors
Here is a link that might be useful: solar heat information
