According to CSA testing, over the course of an entire swimming season in southern Ontario, a typical 4' x 10' rubber/plastic solar
panel can produce about 1.3 Gigajoules of heat energy to heat your pool.
Effectiveness of rubber/plastic solar panels for pools...
That's about 11k btu (British Thermal Units) per day (over a theoretical 120 day pool season). A typical 250k btu per hour natural
gas pool heater puts that amount of heat into your pool in about 3 minutes.
The bottom line? - To produce the same amount of heat energy as a conventional 250k btu pool heater you would need to install
128 four by ten solar panels!