Solar heating is the most cost-effective way to heat the water in your pool to a comfortable temperature year-round. It harnesses the sun's energy to extend your swimming season and costs nothing to operate. Pool heating is the largest use of solar energy in the world... no surprise, since its more economical than a pool heater that uses electricity or gas. What's more, solar heating for your pool is an affordable, one-time investment that pays for itself in 2-4 years.