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<DIV>Hi Don,</DIV>
<DIV> </DIV>
<DIV>
<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 size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Joel Davidson</FONT></DIV></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=I2P@aol.com href="mailto:I2P@aol.com">I2P@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=re-wrenches@lists.re-wrenches.org
href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, June 06, 2009 11:27
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [RE-wrenches] 690.47D
(revisited)</DIV>
<DIV><BR></DIV><FONT id=role_document color=#000000 size=2 face=Arial>
<DIV>
<DIV>In a message dated 6/5/2009 4:31:43 P.M. Pacific Daylight Time, <A
href="mailto:kelly@whidbeysunwind.com">kelly@whidbeysunwind.com</A>
writes:</DIV>
<BLOCKQUOTE
style="BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px"><FONT
style="BACKGROUND-COLOR: transparent" color=#000000 size=2
face=Arial>Mark,<BR>Yes, it's confusing. Which is why I wanted to know what
the Wrenches are<BR>actually DOING in their installations to meet
690.47D.<BR></FONT></BLOCKQUOTE></DIV>
<DIV></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>On a ground mounted array using a driven rod I connect it to the system
ground ( bonded). Sometimes a driven rod at the array is not required. As to
whats the best lightning protection, no actual data one way or another.</DIV>
<DIV> </DIV>
<DIV>Don Loweburg</DIV></FONT>
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