Difference in power in panels on same roof, please help?

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1solarrae

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AZ
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VP of operations - Solar
I continue to have customers that have enphase and will see one-panel produce say 20.00kwh and then like the next one 21.2kwh and they think there is a problem with the first panel. I have explained the standard testing conditions and the range it can fluxuate. But he was proof that what I am saying is true lol. Can anyone point me in the direction where I can show them proof that not all panels produce the same.
 
I haven’t dealt with enphase but panels in the middle of an array that are nice and hot will be less efficient than panels on the perimeter that run cooler.


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So 1.2 over 20 is 6%. Often the data sheet will tell you the tolerance, it may be +/- 5% or 3% or sometimes there's no minus. If it's +/- 3% then that's 6% and within tolerance. If it's not within tolerance then you have to eliminate any differences in dirt and shading. For example if you have even a small difference in shading that accounts for half of the 6% difference then tolerance can account for the rest. Often people don't realize that a somewhat far away tree or a low vent can be making the difference.
 
This is why the public does not need access to this level of data. They don't understand how to interpret it and end up wasting a lot of the installing contractor's time asking questions and refusing to believe the answers.
 
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