[RE-wrenches] GFP and multiple charge controllers

[Darryl Thayer]

Bob do you know of a 4x80 GFDI breaker?  Midnight has a 2X80 correct? and Outback has a 2X80   
Wire size use the tap rule, 10 feet 10% of wire size.  
 

________________________________
 From: "boB at midnitesolar.com" <boB at midnitesolar.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org> 
Sent: Wednesday, April 18, 2012 5:08 PM
Subject: Re: [RE-wrenches] GFP and multiple charge controllers
  


A lot of good replies have come by here but here goes another
      one...

The GFP cannot be used for dual purpose as a disconnect for
      battery
or PV input and you are not allowed to un-ground the system by turning
off the DC input or output breaker.

4 AWG should be fine for 80 amps. If you need/want to use smaller
      wire
than that required for an 80 amp GFP, MidNite makes a 63 amp GFP.

boB




On 4/17/2012 6:42 PM, William Miller wrote:
 
Friends:
>
>Here is a related problem:  If we use an 80 amp GFD (ground
        fault
        detection) breaker, even for a very small array, we have to use
        3AWG CU
        wire from the battery buss to the breaker and from the breaker
        to the FM
        or MX60.  This seems like a big hassle for 5 or 10 amps of
        charging.  A variety of sizes of GFD breakers would be
        helpful.
>
>Here is a bigger problem:  GFD breakers don't really work.  All
        they do is turn off the charge function in hopes that someone
        will find
        the problem.  In the meantime, the negative-to-ground bond is
        removed and module mounting framework could be energized.  PV
        GFD
        breakers are completely different from standard AC GFDI (ground
        fault
        detection and interruption) receptacles and circuit breakers. 
        The
        AC versions interrupt power upstream, the PV versions interrupt
        power downstream from the fault.
>
>See: 
        http://millersolar.com/MillerSolar/case_studies/ground_fauilt/_ground_fault.html
        for some musings on the subject.
>
>As they say on TV: "There had to be a better way!"
>
>William Miller
>
>
>
>At 05:54 PM 4/17/2012, Kent Osterberg wrote: 
> 
>Nathan,
>>
>>I don't think anyone makes a 100-amp PV GFP. The panel mount
          breaker model that's being used for the PV GFP doesn't include
          a 100-amp breaker. 
>>
>>The Classic has a built-in GFP so you shouldn't need an
          external GFP for it. You will need to add a GFP for the FM60 -
          a single 80-amp GFP would work.
>>
>>You can use the dual 80-amp GFP and shut down both PV arrays
          at the same time if the GFP is wired to disconnect the PV
          array from the charge controller input. That's where Outback's
          instructions used to show the GFP, and it is a better place
          for it than on the charge controller output anyway. Midnite's
          instructions show the GFP on the charge controller input, but
          their 80-amp GFP is a single.
>>
>> 
>>Kent Osterberg
Blue Mountain Solar, Inc. www.bluemountainsolar.com  
>>On 4/17/2012 11:08 AM, Nathan Stumpff wrote: 
>> 
>>Wrenches,
>>> 
>>>In a job coming up I have a customer with an existing FM60
            controller,  520 watt (!!) array. We are doing a ton of
            work, including adding a 4 kW solar array with Classic 150
            charge controller. I am trying to figure out how to handle
            the GFP.
>>> 
>>>For the Classic, I need a 90 or 100 A output breaker
            minimum. 80 A is not an option. The OutBack dual GFP is 80
            A, and so it not an option.
>>> 
>>>Is there a 100 A GFP breaker assembly I have just never
            seen? Is there a way to use the Classic’s GFP to run an
            external relay via AUX (to trip the FM60 output breaker at
            the same time)? Any ideas?
>>> 
>>>Thanks,
>>>-Nathan
>>>  
>>>Nathan J. Stumpff - Arctic Sun, LLC
>>>NABCEP Ceritified PV Installer #091209-175
>>>nathan at arcticsun-llc.com 
>>>Office: 907/457-1297
>>>  _________
>> Voice :805-438-5600
>email: william at millersolar.com
>http://millersolar.com
>License No. C-10-773985
>   
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