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<div class="moz-cite-prefix">When a long circuit has surge
protection at only one end, the voltage at the unprotected end of
the wire will rise, by induction, during a lightning event that
causes the surge protection to activate. There should be surge
protection at both ends of long feeders to reduce possible damage
from induced voltages.<br>
<br>
<pre class="moz-signature" cols="72">Kent Osterberg
Blue Mountain Solar, Inc.
<a class="moz-txt-link-abbreviated" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a>
t: 541-568-4882
</pre>
On 9/7/2012 11:14 AM, Jeff Irish wrote:<br>
</div>
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">Kent,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">Surge
protection is at the inverters, 200 feet away, on both the
AC and DC sides. Nothing at the array; never thought we’d
need it there. There’s a 4 string fused DC combiner on the
west pole of each row; no damage visible on any of them and
their fuses were all ok. And yes, each pole of 10 modules
is a separate DC string, 4 are combined into a DC output
circuit to each of four SB7000US inverters.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">Jeff<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">Hudson
Solar<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><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">
<a class="moz-txt-link-abbreviated" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">re-wrenches-bounces@lists.re-wrenches.org</a>
[<a class="moz-txt-link-freetext" href="mailto:re-wrenches-bounces@lists.re-wrenches.org">mailto:re-wrenches-bounces@lists.re-wrenches.org</a>]
<b>On Behalf Of </b>Kent Osterberg<br>
<b>Sent:</b> Friday, September 07, 2012 11:56 AM<br>
<b>To:</b> RE-wrenches<br>
<b>Subject:</b> Re: [RE-wrenches] Extensive Lightning
Damage to Modules<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">Jeff,<br>
<br>
Is there any surge protection in the combiner boxes? Any
damage visible in the combiner boxes? Any fuses or breakers
open in the combiner boxes? Is each pole a single string of
modules or multiple strings of modules?<br>
<br>
While there where undoubtedly ground currents flowing they
probably didn't cause the damage in the module junction
boxes. The PV module and wiring to it form a loop - often a
loop with a large area in the vicinity of the module. The
current from the lightning strike has a tremendous dI/dt and
the changing magnetic field from it will induce voltages in
any wire loop.
<br>
<br>
<o:p></o:p></p>
<pre>Kent Osterberg<o:p></o:p></pre>
<pre>Blue Mountain Solar, Inc.<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.bluemountainsolar.com">www.bluemountainsolar.com</a><o:p></o:p></pre>
<pre>t: 541-568-4882<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<p class="MsoNormal">On 9/7/2012 7:40 AM, Jeff Irish wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">A
customer of ours has recently suffered lightning damage to
31 out of 160 top of pole mounted modules. This is the
first time in 10 years that I’ve seen modules damaged by
lightning. Lots of inverter GF fuses and a few inverters,
but never modules. We’re trying to determine if it was
caused by the lightning flash irradiating the modules or
ground currents.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">The
array consists of 16 DP&W top of pole mounts with 10
modules each, arranged in a square of 4 poles E-W and 4
rows N-S. The poles are 13 feet center to center E-W and
the N-S row spacing is about 50 feet. The poles are 6
inch galvanized Technoposts, augured 5 – 7 feet into the
firm ground, connected with a network of about 160 feet of
bare #6 copper and at least 8 copper plated ground rods.
Altogether we have about 130 square feet of bare metal
surface area connected and buried in the ground at and
around the array.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">The
customer saw lightning strike just after dawn a few weeks
ago a couple hundred feet to the southwest where it also
destroyed two utility pole mount distribution transformers
and ran along the utility wires 100 feet south of the
array. The inverters are 200 feet NW and suffered no
damage. The array and modules look totally fine, except
some of the J-boxes are deformed from heat. Opening the
J-boxes shows varying levels of damage to one or more
diodes, from discoloration to being broken and cracked
open. </span>
<o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">The
odd thing is the pattern of damage (we’ve tested all the
modules individually for Voc and Isc). Only modules in
the south row of 4 poles are damaged, and the damage is
concentrated on the modules closest to the ground; modules
higher up in the air appear OK. Also, damage is less
frequent as you move east, away from the direction of the
strike.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">If
it was caused by ground currents, why would the current
want to go up the poles, why only the southern row of
poles, and why damage more modules closer to the ground
and not those at the top? Is it possible a flash near the
ground irradiated the modules causing a current spike and
the southern row shielded the other rows from most of the
flash? Anyone have experience with this?</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Jeff
Irish, PE</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">President</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Hudson
Solar</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">13
Hook Road</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Rhinebeck,
NY 12572</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">T.845.876.3767x110</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">F.845.876.3912</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""><a
moz-do-not-send="true"
href="mailto:jeff@hudsonsolar.com">jeff@hudsonsolar.com</a></span><o:p></o:p></p>
<p class="MsoNormal"><i><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Solar
Electric Systems</span></i><o:p></o:p></p>
<p class="MsoNormal"><i><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">NYSERDA
Eligible PV Installer</span></i><o:p></o:p></p>
<p class="MsoNormal"><i><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">NABCEP
Certified Solar PV Installer</span></i><o:p></o:p></p>
<p class="MsoNormal"><i><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">NABCEP
Certified PV Technical Sales</span></i><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="color:#919191"><a moz-do-not-send="true"
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<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:9.0pt;color:#6D6D6D">2011 NYSERDA
Excellence in Quality Award | 2011 NYSEIA Award Winner |
2009 Best of the Hudson Valley | 2008 SunPower Dealer of
the Year | EDC Business Excellence Award for Innovation</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
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