[RE-wrenches] GFP and multiple charge controllers

[boB at midnitesolar.com]

On 4/18/2012 4:41 PM, Darryl Thayer wrote:
> Bob do you know of a 4x80 GFDI breaker?  Midnight has a 2X80 correct?


No, but we have a 1 X 63 amp /  300 volt GFP that can be configured as 2 
X 63 amp GFP.

boB






> 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  <http://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 <mailto:nathan at arcticsun-llc.com>
>>>> Office: 907/457-1297
>>> _________
>> Voice :805-438-5600
>> email: william at millersolar.com <mailto:william at millersolar.com>
>> http://millersolar.com
>> <http://millersolar.com/>License No. C-10-773985
>
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