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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>William, <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>In a series string, the one-cell shading in the long dimension
will reduce the voltage of the string by 1/3 of one module. This is often a
small amount of voltage since 12 or 13 modules are in string. In lower voltage
systems, the loss will be much more pronounced. No shading is good and shading
on a portion of a single module in a string will not effect performance
substantially. The problem comes with interrow shading where each module looses
1/3. Now the overall loss is much more than 1/3 of the string because the other
strings will dominate the inverter voltage (assuming you have multiple strings—that
is why you have multiple rows). If only one row is shaded, then the output of
that string will be reduced to operating at the shade light level. If all
strings except the first row are shaded, then a sophisticated inverter will try
to powertrack the array at 2/3 voltage—and therefore 2/3 power. This only
works if the inverter can operate at 2/3 voltage. If not, then the whole array
will likely work off of the first row output and ALL the subsequent rows will
produce power at whatever light level the shade delivers.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Bill.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
re-wrenches-bounces@lists.re-wrenches.org
[mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>William
Miller<br>
<b>Sent:</b> Friday, April 23, 2010 11:26 PM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> [RE-wrenches] Inter-row shading, additional information<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Friends:<br>
<br>
I was incorrect on one point in my previous post on the subject. The
SolarWorld SW230 is comprised of one series string of cells. It acts
somewhat like there are three strings because of the bypass diodes. If you
shade one cell of one group, the bypass diodes kick in and allow the module to
continue to produce power but at a reduced level.<br>
<br>
Our test showed that if the short edge is shaded for more than half of a cell
width on the narrow edge, the total output caved. The same shading on the
long edge reduced output minimally.<br>
<br>
William Miller<br>
<br>
<br>
<br>
<br>
<o:p></o:p></p>
<p><u>Please note new e-mail address and domain:<br>
<br>
</u>William Miller <br>
Miller Solar<br>
Voice :805-438-5600<br>
email: william@millersolar.com<br>
<a href="http://millersolar.com/">http://millersolar.com<br>
</a>License No. C-10-773985<o:p></o:p></p>
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