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<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif";
color:windowtext'>If the modules test out to spec., Are there any mystery
junction boxes where there may be a corroded connection [i.e. – split bolt
or butt splice] and are all the connections tight? <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif";
color:windowtext'>Seen this on several occasions.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif";
color:windowtext'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>Thanks, Dana Orzel<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>Great Solar Works, Inc<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>E - dana@solarwork.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>V - 970.626.5253<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>F - 970.626.4140<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>C - 970.209.4076<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>web - www.solarwork.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Century Gothic","sans-serif";
color:windowtext'>Responsible Technologies for Responsible People since
1988"</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:windowtext'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:14.0pt;font-family:"Century Gothic","sans-serif";
color:windowtext'><o:p> </o:p></span></p>
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<p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif";color:windowtext'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Allan
Sindelar<br>
<b>Sent:</b> Friday, June 25, 2010 12:50 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> [RE-wrenches] Unisolar US64 problem<o:p></o:p></span></p>
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<p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:
12.0pt;margin-left:.5in'>We have an off-grid customer whose PV arrays seem to
be under performing and we're not sure why. The customer has 16 Unisolar
US64 modules, which have a peak output of 3.88 amps, but which were only
putting out from 2 to 2.4 amps each. He has a C40 charge controller, so
they were operating off the peak of the I-V curve (they were operating at 13.6
volts each at the time of the system inspection, instead of the peak, which is
up around 17 volts), but still the amps that they were putting out were lower
than they should be. He used to get 30+ amps (at 24 volts) from his
array, but now he's only getting a little more than 20 amps (611 watts from a
1024 watt array is what my tech saw when he was there a week ago). The
C40 was still in its bulk cycle, not having reached the absorption set-point.
The sunshine was strong (there was no shading all day), there was no haze in
the sky, it was solar noon (1pm MDT), in the mid to high 70's with a breeze,
the arrays are on tilt-up racks, and there was no more than a little dust on
the modules. His arrays are at a year round setting (~latitude), so not
optimal for this time of year, but not that far off. Half of the modules
are 12 years old and half are 10 years old, but it was only last year that he
had 30+ amps coming in, so they couldn't have deteriorated/aged that much in
one year.<br>
<br>
Since there is no combiner box (we didn't design or install this system), each
pair (string) was checked with a clamp-on meter and was putting out only 2 to
2.4 amps. When the C40 was bypassed, there was no increase in current
coming in, so the controller doesn't appear to be at fault.<br>
<br>
The customer's measurement of the performance of his system is the LED on the
C40. He has a meter face on his C40, but he mostly just looks at the
LED. He says that the LED used to go solid green by noon, and now he
doesn't get more than two or three blinks all day.<br>
<br>
Any idea why all his modules might be under performing?<br>
<br>
Thanks<br>
Russell Mueller<br>
Positive Energy<br>
211-M Cruz Alta Rd.<br>
Taos, NM 87571<br>
575-737-9553<o:p></o:p></p>
<p style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:windowtext'>No virus found in this incoming message.<br>
Checked by AVG - www.avg.com<br>
Version: 9.0.830 / Virus Database: 271.1.1/2961 - Release Date: 06/25/10
00:35:00</span><span style='color:windowtext'><o:p></o:p></span></p>
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