What Can You Expect From a Solar Pool Heater in the Phoenix, Arizona area?
The curves above represent a full sized solar heater. We've plotted the daily maximum pool temperatures. We size systems higher if you won't use a cover but notice that 100% of pool area almost equals the performance of 75% of pool area and a cover. Also notice that the realistic maximum season for the solar heated pool is mid March through mid November. Use these charts comparatively. If you're seeing peak pool temperatures of 80F in October with no cover, then scale the charts up 5 degrees to account for that. This is based on average typical airport weather data. Your backyard could have a different climate. The thing to pay attention to is the difference between solar and non-solar temperatures.
All these curves are based on a typical meteorological year which is hour by hour values of air temp, solar radiation, wind levels and humidity based on 10 years of real weather data but the "tmy" isn't average weather data. It is typical weather generated using a complex algorithm. We know solar pool heating's economic numbers are good. What we're interested in is the daily peak pool temperature over what extended season. These plots show you don't need a gas heater. Understand that heating a pool outside the season shown here would be extremely expensive. If you want to heat a pool in this area November through March then you will pay severely for the gas as an enormous amount of fuel would be required, this at times when weather is not conducive to pool use. Sorry, don't shoot the messenger. There are no magic solutions here. There are no "better collectors". These things are black and cold. In the air temperatures we see in Phoenix this type of collector performs at over 90% efficiency. Collectors don't lose heat to the air when the air is as warm as the collector. (collector temp equals pool temp)
75% solar means 75% of the pool's top surface area in collector area. We assumed the cover would always be on the pool 20 hours a day and for 4 hours the cover would come off (for the 2 plots with covers) and moderate pool activity would occur. We created these charts using Enerpool solar simulation software. We do not have confidence in any other computer program like this. Click here to learn about this software and its history. You can even download the software yourself and put it to use if you're an engineer type.
Dustin Crandall, owner of AZ Water Solutions has invested in two web monitoring systems allowing us to see real time solar performance.
This one is actually a hot tub at a condo complex that is heated year round with propane and assisted with a large Powerstrip solar pool heater. We learned that heating a hot tub at 100 degrees is half as effective as heating a pool at 84 degrees.
This one is a pool. You can click back and forth day by day and look at every temperature. These sites verify that the sizing predictions we opffer are realistic and prove we aren't just making this up. Solar works.