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Maui Solar PV Design-Pro program: BUG! - Page 2

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Posted by Solar Guppy on January 16, 2004, 2:37 am
I Misunderstood your example as to mean 50 ft total !

I didn't double check HP's numbers , but the Strands might be a difference ,
my first system wired end to end in 6 Gauge , but I believe it had more like
12-13 strands , not 7 in the conductor ... more variables I guess

I have found PVwatts to be reasonably close to my system in net generation ,
but I paid attention to every little thing I could to get the best
performance possible from the first arrays. (seasonal tilts , end to end 6
gauge , cleaning regularly)

I guess I don't see the point of a 150.00 program to tell me system output
when there are so many variables in the weather alone to make its predicted
output not much closer than PV watts in the end. If your off , well add
another string of panels (two for 48 volt systems) and your done with it

On the topic of losses , none of the above even touches on the issue of
module tolerances. My latest system , the "155 watt" panels ranged from a
low of 146 to a high of 179 watts ... I doubt any program would have a clue
how to estimate factory yields , then there's the issue if you use these
panels in 48 volt strings or 300 volts Strings ... the later will lose close
to 5% due to the current being limited to the weakest panel ... So much for
High Voltage Strings being the best solution !




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