[RE-wrenches] GFP and multiple charge controllers

[boB at midnitesolar.com]

Here is Robin's 2 cents worth on this subject....

In a PV input circuit to a charge controller that has a 63 or 80 amp 
DC-GFP, it is perfectly legal to use a small wire. That is because you 
will also have the appropriate sized breaker in series with the DC-GFP 
breaker. If you want to use 10AWG wire, you will need a 30 amp DC 
breaker in series with your 63 or 80 amp DC-GFP breaker. The DC-GFP is 
being used as a switch, not as a breaker. I used to use an 80 amp switch 
on the dual Outback DC-GFP rather than a breaker, but it really does not 
matter if it is a breaker or a switch. The real over-current disconnect 
breaker is the device that should determine your wire size.

I'm not sure why Outback changed the DC-GFP to the battery circuit? It 
will work, but you still are required to have another breaker in series 
with it. The NEC intends for the DC-GFP to be installed in the PV circuit.

If you need a 100 amp DC-GFP, then you will need to use a Classic. I 
cannot think of any system today that would require a 100 amp DC-GFP though.

Robin Gudgel

MidNite Solar





>>>>
>>>> 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
>>>>
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