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I've checked several PV modules under load in past years and they
all seem to do this.<br>
<br>
Just cell mis-match I was guessing.<br>
<br>
boB<br>
<br>
<br>
<div class="moz-cite-prefix">On 5/17/2018 3:19 PM, Corey Shalanski
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CA+SmqZ2oS1zE_niWecdanFyW3BH5F=mOAMVDrB6jq5Wgz1O8pg@mail.gmail.com">
<div dir="ltr">On a recent utility-scale PV installation we
noticed a strange phenomenon on a single string on a single
inverter. An IV curve (attached) reveals that the measured
performance characteristics for this string (solid line) are
significantly less than the expected values (dotted line). For
reference, the ambient temperature was 31°C and the irradiance
was 1010 W/m².
<div><br>
</div>
<div>The phenomenon that more so caught our attention is
apparent on a thermal image (also attached) of the modules in
this string. For lack of a better term I would describe the
distribution of cell temperatures as resembling a
"checkerboard" or "scattershot" (random) pattern, ranging
between roughly 55°C and 70°C. Interestingly this phenomenon
was only apparent while the inverter was operating, i.e. with
the inverter turned off the modules revert to a much more
uniform temperature distribution nearer to 55°C, instead
varying by only a couple degrees across the entire
module/string.</div>
<div><br>
</div>
<div>There was no apparent physical damage to the modules.</div>
<div><br>
</div>
<div>Can anyone offer any suggestions about what might be
causing this phenomenon?</div>
<div><br>
</div>
<div>--</div>
<div>Corey Shalanski</div>
<div>Joule Energy</div>
<div>New Orleans, LA</div>
</div>
<br>
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