[RE-wrenches] Long MC Cable Mid String

Wind-sun.com windsun at wind-sun.com
Wed Apr 22 06:13:58 PDT 2009


Quite simply, you don't CARE about the voltage drop as volts.

What you care about is the PERCENTAGE. Dropping 1 volt in a 12 volt system is not acceptable. Dropping 10 volts in a 500 volt system is .2 percent.

..................................................................................................
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..................................................................................................
  ----- Original Message ----- 
  From: Drake Chamberlin 
  To: dkatz at aeesolar.com ; RE-wrenches 
  Sent: Wednesday, April 22, 2009 7:15 AM
  Subject: Re: [RE-wrenches] Long MC Cable Mid String


  I have scratched my head on this one before, because it seems that two terminals bonded together by a wire are essentially the same terminal.  The theoretical voltage difference on a terminal is zero.  How do we figure a voltage drop on a wire that has near zero volt potential between the ends of the wire.  Can we really use the voltage of the entire array to figure the drop on an interconnect between two modules?   If so, why can we do this?

  Thanks,

  Drake 



  At 07:49 PM 4/21/2009, you wrote:

    David,
    There will be less than a 1 volt drop in 36 feet of 10 AWG at the 11 amps you get from the Evergreen modules.  I don't think anyone will notice.
    David

    David Katz


    David Palumbo wrote: 

      Does the following series string wiring cause a problem? With  (18) Evergreen ES-A 205's (low voltage modules 18.4Vmp) in series feeding a grid tie inverter with a long series connector in the middle of the string.  (2) Top Of Pole 9 module mounts with the series connection from module #8 on the first pole to module #9 on the second pole. This MC cable connection would be, about, 36 feet in length to go 10' down the pole below grade 18" for 13' and back up the second pole 10' (in conduit all the way) .
       
      Will this extra long series wire cause problems?
       
      I could use other modules of course but that would raise the cost per watt by 70 cents.
       
      Dave
       
      David Palumbo, President
      Independent Power LLC
      462 Solar Way Drive
      Hyde Park, VT 05655
      NABCEP Certified
      www.independentpowerllc.com 
       





 
_______________________________________________
    List sponsored by Home Power magazine

    List Address: RE-wrenches at lists.re-wrenches.org

    Options & settings:
    http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org 

    List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

    List rules & etiquette:
    www.re-wrenches.org/etiquette.htm

    Check out participant bios:
    www.members.re-wrenches.org
  Drake Chamberlin
  Athens Electric
  OH License 44810
  CO License 3773
  740-448-7328
  740-856-9648 



------------------------------------------------------------------------------


  _______________________________________________
  List sponsored by Home Power magazine

  List Address: RE-wrenches at lists.re-wrenches.org

  Options & settings:
  http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

  List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

  List rules & etiquette:
  www.re-wrenches.org/etiquette.htm

  Check out participant bios:
  www.members.re-wrenches.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20090422/809cd1ca/attachment-0004.html>


More information about the RE-wrenches mailing list