Hot Sun Industries Inc., San Diego, California
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. 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 and payback period is no longer than 3 years. 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 messanger. 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 colelctor 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. That would be 8) 4x12 collectors if the pool is a standard 16x32. 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 "Enerpool" 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.
We have many references in this area and we work with several companies that can do the installation for you if you're not one to climb ladders but we don't have "dealers". You want to buy this from me as a turn-key kit with full instructions specific to your situation. You want to be the general contractor. You hire the laborer or we'll get someone for you and you make sure they do what they are supposed to. Its simple when you have full access to an expert that has experience with every weird anomoly you might encounter in your case. Our experience has been that we can't do this business through dealers without losing the expertise level down the distribution pyramid. Buy direct from the source and the installers will just have to show you what they are making per hour instead of hiding it in materials profit. Two interesting notes about Arizona. There is a 25% tax rebate that these systems qualify for. Also Homeowners associations do not have a legal right to stop you from using solar energy even if it means the neighborhood committee doesn't like the black thing on your roof.
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