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<DIV>In 1983 Arco Solar and the Lightning & Transients Research
Institute,<BR>St. Paul, MN, presented a paper at the Greece PV conference
titled<BR>"Ability of Photovoltaic Modules to Withstand Lightning
Strikes."<BR><BR>Summary: The ability of glass superstrate and metal/plastic
substrate<BR>modules to withstand lightning strikes was examined. Each of 3
different<BR>types of modules were exposed to 4 nearby and 1 direct strike of
high<BR>voltage long arc simulated lightning (400,000 volts, 10,000 amps),
and<BR>to 1 direct strike of high current, long duration lightning (150,000
to<BR>175,000 amps, 50,000 volts). Visual and electrical
examination<BR>demonstrated that the high voltage strikes produced no electrical
damage<BR>to the glass superstrate modules and little to the plastic
substrate<BR>module. The high current, long duration strike resulted in
varying<BR>degrees of physical damage to all modules but little or no loss
in<BR>electrical performance.<BR><BR>Conclusions: The experimental data indicate
that a glass front module<BR>with a rigid metal frame is able to withstand
almost any lightning<BR>strike if the frame is grounded to the earth. The metal
frame acts as a<BR>grounding rod attracting all the current to it. However, a
strike which<BR>breaches the integrity of the encapsulation might, under
some<BR>conditions, eventually destroy the module. Data from the field appear
to<BR>concur with the experimental data presented in this paper but
also<BR>indicate that while the modules survive a lightning storm,
additional<BR>protection may be required for the cabling, power
conditioning<BR>equipment, and control systems. A grounding rod will protect the
array<BR>from direct strikes but further protection is required for
induced<BR>voltages and side flashes they can create. Shielding (e.g.
coaxial<BR>cables) will protect the wiring. The terminals of the balance of
system<BR>components can be protected by the use of nonlinear circuit
elements<BR>known as terminal protection devices. These devices may be
nonlinear<BR>resistors or varistors, semiconductor junction devices and
dielectric<BR>breakdown devices or sparkgaps. The degree of protection needed
for any<BR>particular installation will be determined by factors such as
site<BR>location, size of the array, safety considerations and cost.<BR></DIV>
<DIV><FONT face=Arial size=2>Joel Davidson</FONT></DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=solarone@charter.net href="mailto:solarone@charter.net">Matt
Tritt</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=daryl_solar@yahoo.com
href="mailto:daryl_solar@yahoo.com">daryl_solar@yahoo.com</A> ; <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">RE-wrenches</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=trangdonovan@gmail.com
href="mailto:trangdonovan@gmail.com">trang donovan</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, March 09, 2009 11:04
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] Lightning
protection system</DIV>
<DIV><BR></DIV>Hi Darryl,<BR><BR>Just to see what your take would be, and
other's - what would the case be should the modules have non-conducting frames
(or even no frames)is the case with some systems on the market?<BR><BR>Matt
T<BR><BR>Darryl Thayer wrote:
<BLOCKQUOTE cite=mid222739.3029.qm@web51904.mail.re2.yahoo.com type="cite"><PRE wrap="">Yes the electric power and atmospheric grounding systems should be connected together to serve as a larger better grounding system. The Electrical code requires that at only one point does the neutral (grounded) conductor of the electrical power system get connected to the grounding system, this is to prevent the grounding electrode system from carrying electrical power system currents. The electrical power system is to be grounded to prevent the electrical power system from differentiating its self via the injection of energy from other electric power sources including atmospheric electrical energy.
The lightening protection system is to create a path from the atmospheric energy to the earth grounding system. ((Wind rain, dust and friction cause the atmosphere to become charged relative to the earth, conducting objects can build a charge if not electrically connected to the earth, these current flow all the time, although they are small sometimes, and in the case of a lightening strike incredibly large. Even small currents can build large voltages and fail electronic components.
The frames of solar modules are electrical conduction components not normally charged that can present a personal, and physical damage potential (life-property) if they become charged by the electrical power system and therefor the underwriters require they be protected by grounding. This accidental energy need to be safely returned to the electrical power system, and properly this is called bonding back to the neutral conductor. This grounding is described by the NEC in 690 and 250 primarily. The frames of the modules can become charged by atmospheric energy energy, this energy needs to be returned to the earth, via the lightening protection system, ie grounding electrode system. The code says little about this, however, it is addressed in 690 and 250.
Sorry I said so much.
Darryl
--- On Fri, 3/6/09, Drake Chamberlin <A class=moz-txt-link-rfc2396E href="mailto:drake.chamberlin@redwoodalliance.org"><drake.chamberlin@redwoodalliance.org></A> wrote:
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">From: Drake Chamberlin <A class=moz-txt-link-rfc2396E href="mailto:drake.chamberlin@redwoodalliance.org"><drake.chamberlin@redwoodalliance.org></A>
Subject: Re: [RE-wrenches] Lightning protection system
To: "RE-wrenches" <A class=moz-txt-link-rfc2396E href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></A>
Date: Friday, March 6, 2009, 8:47 AM
I didn't get a reply to the question about connecting
the GEC to the
lightning protection system on the 8 story building.
Although this
may seem like an intrinsically dangerous idea, a lightning
protection
system is required to be bonded to the building grounding
electrode system.
"250.106 Lightning Protection Systems.
The lightning protection system ground terminals shall be
bonded to
the building or structure grounding electrode system."
It would therefore seem that the suplemental ground could
connect to
that system as well, and in fact use the existing
conductor. Any
input would be welcome.
Thanks,
Drake
At 09:19 PM 3/4/2009, you wrote:
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">Hello Wrenches,
Can the supplemental grounding electrode conductor be
</PRE></BLOCKQUOTE><PRE wrap="">connected to a
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">lightning protection system?
We have a case where it would be difficult to run a GEC
</PRE></BLOCKQUOTE><PRE wrap="">down a multi
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">story building, but have a convenient copper wire, from
</PRE></BLOCKQUOTE><PRE wrap="">a lightning
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">protection system, that runs to a rod.
Thank you,
Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648
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</PRE></BLOCKQUOTE><PRE wrap="">Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
740-448-7328
740-856-9648
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