Quoting from Solar Guppy's answer on a previous post:
Quote:
"Just about all charge controllers are limited to a maximum of 150 volts, and cold temperatures is when this condition is most likely
3 panels in series ( using 24V ) is the limit. You then have a total wattage limit of about 3kW for a charge controller. I looked up the specs on the Sharp 224 watt panel and its a real oddball, somewhere between a 18V and 24V panel, the only one with those voltages
If you used a panel like an 195 watt evergreen you could have 4 panels to a string as those are 18V panels. Then you would have 3 parallel strings for a combined wattage of 2340 for each XW-60-150 ( total system wattage of 4680 )
I would recommend the Evergreen 195's ( or 190's ) over any other panel. Evergreens power tolerances are the best in the industry and its a standard voltage. Sharp is an odd-ball one off voltage and they make there solar cell wafers 1/2 to 1/3 the thickness of other manufactures, I would not be selecting those panels for my system.
Also if you ever have to replace one, it could be impossible if the manufacture stop production which they do almost every year, if you have a common voltage of 12/18/24V you have many more options. Evergreen has made the 190's for close to 6 years now I believe"
I just couldn't find those specifications about the voltage on either panel. What I found was the Sharp 224 at 36.6Voc and Evergreen 190 at 32.8Voc. It is my understanding that Voc is what is necessary to calculate for when hooking panels up, because that is the maximum possible voltage the panel would ever produce.
And regarding hooking the panels up to the charge controller, if the controller can withstand 150V, 3 Sharp panels could produce at most 110V, which to my understanding means that 4 could be hooked up producing at most 147V, still under the 150V maximum. But maybe the practical real-world maximum really is some bit lower than the posted maximum?
Does it really matter that the Sharp panel is much thinner than the Evergreen panel? What effect does that have? The Sharp panel still achieves a higher efficience even with a thinner panel. Will the thinner Sharp wear out faster?
I definitely agree that the tolerance of the Evergreen panels are better than the Sharp panels. Evergreen quotes -2% / + 4%, while Sharp quotes -5% / + 10%. I think it is pretty unlikely to get a Sharp panel doing +10%, but you can get Sharp panels at -3% to -5% while you won't find any Evergreen 190 panels doing worse than -2%.
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