[RE-wrenches] wrenches] Short Circuit Cell Damage

[Drake]

If you cut them one at a time, it won't hurt the 
cutters, but you can get a good shock. Cutting is 
not that difficult, but the stripping can be a bit dicey.


At 07:46 PM 9/18/2012, you wrote:
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>
>If you cut them during the day, under sunlight 
>conditions it can do bad things to the wire cutters.
>
>Been there before,
>Bob Ellison
>
>From: re-wrenches-bounces at lists.re-wrenches.org 
>[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of john
>Sent: Tuesday, September 18, 2012 1:43 PM
>To: re-wrenches at lists.re-wrenches.org
>Subject: Re: [RE-wrenches] wrenches] Short Circuit Cell Damage
>
>Mark,
>    As far as cutting the jumper for us 
> nightowls, it is easy.  Wait until dark.  The 
> sun actually turns off every day!.
>And for the new people on the block, polarity 
>can still be determined after dark.  All you 
>need is a microvolt to get polarity.
>
>John
>CV Solar
>-----Original Message-----
>From: benn kilburn <<mailto:benn at daystarsolar.ca>benn at daystarsolar.ca>
>To: RE-wrenches 
><<mailto:re-wrenches at lists.re-wrenches.org>re-wrenches at lists.re-wrenches.org>
>Sent: Tue, Sep 18, 2012 1:48 am
>Subject: Re: [RE-wrenches] Short Circuit Cell Damage
>Mark,
>Shorting the string should not be an issue.
>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?!?!
>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.
>
>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.
>
>Cheers,
>benn
>DayStar Renewable Energy Inc.
><http://www.daystarsolar.ca/>www.daystarsolar.ca  *  Ph: 780-906-7807
>Construction Electrician Solar Photovoltaic Systems Certified
>Certificate # 0007S
>HAVE A SUNNY DAY
>
>On 17/09/12 9:50 PM, "Mark Frye" 
><<mailto:markf at berkeleysolar.com>markf at berkeleysolar.com> wrote:
>
>Wrenches,
>
>True or False: In a nominal sort of grid tied situation with string Voc
>at about 300 VDC and Isc at about 6 or 7 amps......It is OK to install
>modules on a roof in the sun and short the pos and neg together
>indefinitely.
>
>In other words modules can handle operating at Isc continuously without
>damage. It is only if you get localized shading AND a failed bypass
>diode that damaging hot spot heating can lead to failure?
>
>I am reviewing an installation manual that recommends completing the
>home run by connecting the pos and neg of the string with a single
>jumper cable, folding the cable on itself in order to push it through to
>a j-box and at some point later on, cutting the jumper in the j-box to
>terminate the pos and negs to the home run.
>
>I am concerned both about maintaining the string in a short circuit
>condition and cutting the jumper while energized.
>
>Any thoughts?
>
>Mark Frye
>Berkeley Solar Electric Systems
>
>
>
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