<font color='black' size='2' face='arial'>
<div><FONT style="BACKGROUND-COLOR: transparent" face="Arial, Helvetica, sans-serif">Mark,</FONT></div>
<div> As far as cutting the jumper for us nightowls, it is easy. Wait until dark. The sun actually turns off every day!.<br>
And for the new people on the block, polarity can still be determined after dark. All you need is a microvolt to get polarity. </div>
<div><br>
John</div>
<div>CV Solar<br>
</div>
<div style="FONT-FAMILY: arial,helvetica; COLOR: black; FONT-SIZE: 10pt">-----Original Message-----<br>
From: benn kilburn <benn@daystarsolar.ca><br>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org><br>
Sent: Tue, Sep 18, 2012 1:48 am<br>
Subject: Re: [RE-wrenches] Short Circuit Cell Damage<br>
<br>
<div id=AOLMsgPart_2_91e216c6-2ac4-43ed-aaa5-7d1988abf6d6>
<div>
<div>
<div><FONT class=Apple-style-span color=#00007f>Mark,</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Shorting the string should not be an issue. </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Unless you work at night, obviously there will be an arc when you cut the jumper, so remember to cover the whole string with an opaque covering beforehand… I think I remember reading that somewhere?!?! </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Or just be careful, try to do it when the irradiance is low (less current), separate the cut wires quickly and make sure you have left enough wire in the box so that you are not working with short (and energized) wires in a metal box. put a wire nut on one wire while you handle and terminate the other.</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>A safer method, if possible, would be to leave an easily accessible module interconnection un-connected until you have terminated the home run (+)&(-), then go back and make the final module interconnection.</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Cheers,</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>benn</FONT></div>
<div>
<div>
<div><FONT class=Apple-style-span color=#00007f>DayStar Renewable Energy Inc. </FONT></div>
<div><FONT class=Apple-style-span color=#00007f><A href="http://www.daystarsolar.ca/" target=_blank>www.daystarsolar.ca</A> * Ph: 780-906-7807 </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Construction Electrician Solar Photovoltaic Systems Certified</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Certificate # 0007S</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>HAVE A SUNNY DAY</FONT></div>
</div>
</div>
</div>
</div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<SPAN id=OLK_SRC_BODY_SECTION>
<div>
<div><FONT class=Apple-style-span color=#00007f>On 17/09/12 9:50 PM, "Mark Frye" <<A href="mailto:markf@berkeleysolar.com">markf@berkeleysolar.com</A>> wrote:</FONT></div>
</div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div>
<div>
<div><FONT class=Apple-style-span color=#00007f>Wrenches,</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>True or False: In a nominal sort of grid tied situation with string Voc </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>at about 300 VDC and Isc at about 6 or 7 amps......It is OK to install </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>modules on a roof in the sun and short the pos and neg together </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>indefinitely.</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>In other words modules can handle operating at Isc continuously without </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>damage. It is only if you get localized shading AND a failed bypass </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>diode that damaging hot spot heating can lead to failure?</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>I am reviewing an installation manual that recommends completing the </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>home run by connecting the pos and neg of the string with a single </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>jumper cable, folding the cable on itself in order to push it through to </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>a j-box and at some point later on, cutting the jumper in the j-box to </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>terminate the pos and negs to the home run.</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>I am concerned both about maintaining the string in a short circuit </FONT></div>
<div><FONT class=Apple-style-span color=#00007f>condition and cutting the jumper while energized.</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Any thoughts?</FONT></div>
<div><FONT class=Apple-style-span color=#00007f><br>
</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Mark Frye</FONT></div>
<div><FONT class=Apple-style-span color=#00007f>Berkeley Solar Electric Systems</FONT></div>
<div><br>
</div>
<div style="COLOR: rgb(0,0,255)"><br>
</div>
</div>
</div>
</SPAN></div>
<!-- end of AOLMsgPart_2_91e216c6-2ac4-43ed-aaa5-7d1988abf6d6 -->
<div style="BACKGROUND-COLOR: #fff; MARGIN: 0px; FONT-FAMILY: Tahoma, Verdana, Arial, Sans-Serif; COLOR: #000; FONT-SIZE: 12px" id=AOLMsgPart_3_91e216c6-2ac4-43ed-aaa5-7d1988abf6d6><PRE style="FONT-SIZE: 9pt"><TT>_______________________________________________
List sponsored by Home Power magazine
List Address: <A href="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</A>
Options & settings:
<A href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target=_blank>http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</A>
List-Archive: <A href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" target=_blank>http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</A>
List rules & etiquette:
<A href="http://www.re-wrenches.org/etiquette.htm" target=_blank>www.re-wrenches.org/etiquette.htm</A>
Check out participant bios:
<A href="http://www.members.re-wrenches.org/" target=_blank>www.members.re-wrenches.org</A>
</TT></PRE></div>
<!-- end of AOLMsgPart_3_91e216c6-2ac4-43ed-aaa5-7d1988abf6d6 --></div>
</font>