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Wrenches,<br>
We have been hired to serve as independent consultants on a large
Sunny Boy/Sunny Island off grid project. The array and the battery
bank (of unknown type and capacity at this time) have proven
inadequate for the loads and the owners want outside review of the
proposed upgrade, which we have agreed to provide.<br>
<br>
In reviewing project information, I have learned that each Sunny Boy
inverter is serving 32 260W modules in three parallel strings. Two
of the strings have eleven modules and one has ten. This is to us a
fundamental violation of good design practice, such that we have
never tried it to learn the results. That's my question: what will
be the output of this array of mismatched strings? <br>
<br>
We figure that the inverter will find a MPPT "sweet spot" that is
pulled down below the MPP of the two eleven-module strings, to where
the ten-module string's contribution is close enough to its MPP to
maximize the output of the three strings together. This would result
in slightly more than 30 modules' worth of wattage output from the
32-module array. <br>
<br>
We have not yet been to the installation or seen photos of it. My
verbal understanding is that the 96 modules are on eight pole-top
racks. It would be fun to figure out the array wiring on this one.<br>
<br>
Has anyone encountered this mismatch situation? What did you learn?<br>
<br>
Thank you,<br>
Allan <br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com"><font
color="#000099" face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font
face="Times New Roman, Times, serif"><br>
<span style="font-size: 10pt;">NABCEP Certified Photovoltaic
Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font>
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