# Photovoltaic DC arc fault circuit protection



## chicken steve (Mar 22, 2011)

http://www1.eere.energy.gov/solar/pdfs/pvmrw2011_p06_gen_ji.pdf

Interesting , and not the first time a standard has been forwarded before manufacturing and marketing 

I'm also under the impression that afci technology recognizes wave form disturbances, so i'm all the more interested in how this occurs DC ?

Anyone out there seen these little jems >?

required per 2011 690.11 btw.....


~CS~


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## backstay (Feb 3, 2011)

Here


The Sunny Boy 5000/6000/7000-US-12 can be used in 208, 240 and 277 VAC applications. The 8000-US-12 can be used in 240 and 277 VAC applications. These inverters also come with a DC disconnect switch that connects to the bottom of the inverter. The disconnect has an integrated fused 4-circuit string combiner that can be used with fuses up to 20 amps and are shipped with 15 A fuses The disconnect also has an input main lug for array DC input (to be used with a separate combiner box). All four models are field-configurable for positive ground systems and have built-in ground-fault and arc-fault detection and interruption.


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## FlyingSparks (Dec 10, 2012)

I hope outback power comes out with a three phase inverter.


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## backstay (Feb 3, 2011)

FlyingSparks said:


> I hope outback power comes out with a three phase inverter.


You know you can stack FX inverters to make 3 phase? Page 22

http://www.wmrs.edu/projects/BARene...ericas%20and%20Mobile%20manual%20rev%2072.pdf


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## chicken steve (Mar 22, 2011)

backstay said:


> Here
> 
> 
> The Sunny Boy 5000/6000/7000-US-12 can be used in 208, 240 and 277 VAC applications. The 8000-US-12 can be used in 240 and 277 VAC applications. These inverters also come with a DC disconnect switch that connects to the bottom of the inverter. The disconnect has an integrated fused 4-circuit string combiner that can be used with fuses up to 20 amps and are shipped with 15 A fuses The disconnect also has an input main lug for array DC input (to be used with a separate combiner box). All four models are field-configurable for positive ground systems and have built-in ground-fault and arc-fault detection and interruption.


Ok, guess you were the poster to ask backstay

we don't need to run out an buy a DC afci

Sunny's manual describes it on page 15 as 

"A means of detecting and interrupting _serial _arcs"

I'd still like to know more about this new widget......

~CS~


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## FlyingSparks (Dec 10, 2012)

backstay said:


> You know you can stack FX inverters to make 3 phase? Page 22
> 
> http://www.wmrs.edu/projects/BARene...ericas%20and%20Mobile%20manual%20rev%2072.pdf


I want one with no stacking required haha Kind of like a gs8048-3 :laughing:


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## HARRY304E (Sep 15, 2010)

chicken steve said:


> http://www1.eere.energy.gov/solar/pdfs/pvmrw2011_p06_gen_ji.pdf
> 
> Interesting , and not the first time a standard has been forwarded before manufacturing and marketing
> 
> ...


:thumbsup:


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## chicken steve (Mar 22, 2011)

If in fact the DC~afci components are in the inverter, how is it the protect anything upstream on the roof , as the UL standard suggests?

~CS~


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## chicken steve (Mar 22, 2011)

The Solar Guru's opine

but far from unison ....

~CS~


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## backstay (Feb 3, 2011)

chicken steve said:


> If in fact the DC~afci components are in the inverter, how is it the protect anything upstream on the roof , as the UL standard suggests?
> 
> ~CS~


It doesn't, but in some inspectors minds, you can't put breakers in the combiner box on the roof either. That is why EMT is the minimum for protecting the conductors from the panels through the building. I put them up there. But putting ground mounts in solves a lot of theses problems. Or stay under 80 volts.


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## drumnut08 (Sep 23, 2012)

backstay said:


> It doesn't, but in some inspectors minds, you can't put breakers in the combiner box on the roof either. That is why EMT is the minimum for protecting the conductors from the panels through the building. I put them up there. But putting ground mounts in solves a lot of theses problems. Or stay under 80 volts.


. The only breaker I've ever seen in a combiner box , was the main ( through the door ) disconnect . Obviously , all string circuits are protected via hinged fuse holder assemblies . Now that I think about it , I'm not so sure that was even a breaker ? More like a very fast acting DC switch . Never seen the combiner breakers though .


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## chicken steve (Mar 22, 2011)

backstay said:


> It doesn't, but in some inspectors minds, you can't put breakers in the combiner box on the roof either. That is why EMT is the minimum for protecting the conductors from the panels through the building. I put them up there. But putting ground mounts in solves a lot of theses problems. Or stay under 80 volts.


While that makes sense backstay, it's already addressed via 690.31 , w/o 690.11 having the _same_ 210.12 exceptions FOR conductors in raceway, etc, ....

Besides, the Ul doc clearly shows a pix of PV conductors being afci protected _before _the inverter

Unless every PV module is run exclusive (not in series) back to the inverter under 80 volts, how is this accomplished?

~CS~


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## backstay (Feb 3, 2011)

drumnut08 said:


> . The only breaker I've ever seen in a combiner box , was the main ( through the door ) disconnect . Obviously , all string circuits are protected via hinged fuse holder assemblies . Now that I think about it , I'm not so sure that was even a breaker ? More like a very fast acting DC switch . Never seen the combiner breakers though .


Except single string systems, all the systems I've installed have them.


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