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Stand Alone Solar Arc-fault protection devices.

I'm putting in an order for four of these. I only need one, as each unit can handle 4 strings. I'll hopefully be able to report back in the next few weeks, depending how long it takes to ship and when I have time to get it set up in between work and travel. If it works out, I can resell two or three of them. Will probably look for around 50 bucks shipped per unit, that would be pretty much my cost plus shipping.
 
I emailed the company about it, and they sent me the following product documentation.
 

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  • FR-PVMS-HKB_Datasheet_V1.4[75019].pdf
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  • FR-PVMS-TFQB_Datasheet_V1.6.pdf
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  • FR-PVMS-TFQB_Datasheet_V1.6[75017].pdf
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Those are the datasheets for some of their other products. Here's the manual and UL results for the AS4A. I couldn't find the datasheet.
I did notice they have a couple of standalone arc fault "box" integrated things, you can see the datasheets for those here: https://www.fonrich.com/DC-Arc-Fault-Detector-dc212164.html
 

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  • FR-DCMG-AS4A_UL_certificate.pdf
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  • FR-DCMG-AS4A_UM_EN_V1.7.pdf
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There are lots of cheap micro-inverters out there that do arc fault well. At least one company I know of has an approximate 80% failure rate by 5 years. I have 36 panels on my roof with TIGO optimizers and a pair of string inverters, one of which has a failing arc fault monitor, and neither of which would trigger a PV shutdown at the panels the way I want... Buying 36 new microinverters and completely rewiring my array isn't exactly high on my list, and they'd have to be spectacularly cheap to match the 50 bucks for a 4-string monitor that is the AS4A
 
I'm putting in an order for four of these. I only need one, as each unit can handle 4 strings. I'll hopefully be able to report back in the next few weeks, depending how long it takes to ship and when I have time to get it set up in between work and travel. If it works out, I can resell two or three of them. Will probably look for around 50 bucks shipped per unit, that would be pretty much my cost plus shipping.
If it works out, I'm down to buy one. Just need to figure out how to get it to turn off power to my Tigos - haven't done much more than skim though their documentation at this point. Saw the below diagram and figured I'd just need the PLC Transceiver and the Monitor - just not sure what i'd need to do to get the monitor to send a signal to a relay or something to turn off the Tigos.

1658937097087.png
 
The diagram you included doesn't have the arc fault monitor... those pieces are the Fonrich rapid shutdown system (SafeSolar) which Tigo already handles well.

This pinout is from the AS4A manual. My intention is to connect the ALM_OUT to some sort of relay. Still need to figure out what they mean by a 'direct drive relay' not needing a pull-up resistor... in any case i think/hope that "output low level when there is arc alarm" means i can tie this in with some sort of relay to the tigo's AUX pv-off input.

It says "once fault arc occurs Immediately issue an alarm signal to inform the inverter or other actuators to cut off the fault circuit and effectively prevent fire hazards such as fires caused by arcs" in the description, so i think i can find a way to wire it up

1658937874369.png
 
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The diagram you included doesn't have the arc fault monitor... those pieces are the Fonrich rapid shutdown system (SafeSolar) which Tigo already handles well.

Hah! Oops, after looking more, I suppose it doesn't - I just saw their response to my question about the Arc Fault needs:

"I promote our new product that is called "Smart PV Safety Controller", which integrates rapid shutdown and arc fault detection. Please see the attached docs for reference."

And then skimmed what they sent - probably should exercise better due diligence before posting next time. :S
 
subscribing and watching.

This implies that you can have standard MC4 cables to the combiner box, but it must be in metal conduit (or buried) all of the way after that.

has anyone done any further review/research on this? How about MC cable.... is that equivalent and sufficient protection in place of conduit once inside the building?

i'm now considering placing all of my MC4 connectors within 3/4" EMT inside the rails for fire protection. sounds like something that's regularly done for PV wire on the roof.

 
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any input?

690.11 Arc-Fault Circuit Protection (Direct Current).​

Exception: For PV systems not installed on or in buildings, PV output circuits and dc-to-dc converter output circuits that are direct buried, installed in metallic raceways, or installed in enclosed metallic cable trays are permitted without arc-fault circuit protection. Detached structures whose sole purpose is to house PV system equipment shall not be considered buildings according to this exception.


How should this read? Like this?

Below are permitted without arc-fault circuit protection:
  • PV systems not installed on or in buildings
  • PV output circuits and dc-to-dc converter output circuits that are:
    • direct buried
    • installed in metallic raceways
    • installed in enclosed metallic cable trays
 
any input?

690.11 Arc-Fault Circuit Protection (Direct Current).​

Exception: For PV systems not installed on or in buildings, PV output circuits and dc-to-dc converter output circuits that are direct buried, installed in metallic raceways, or installed in enclosed metallic cable trays are permitted without arc-fault circuit protection. Detached structures whose sole purpose is to house PV system equipment shall not be considered buildings according to this exception.


How should this read? Like this?

Below are permitted without arc-fault circuit protection:
  • PV systems not installed on or in buildings
  • PV output circuits and dc-to-dc converter output circuits that are:
    • direct buried
    • installed in metallic raceways
    • installed in enclosed metallic cable trays

I'm curious about this as well.

So I could (assuming no local codes block it), direct bury pv cable (if rated for direct bury, or put it in conduit and buried), up to my house, at which point it would need to go in metallic raceway..

But, I want all my equipment in my garage, on the other side of the wall, not outdoors. Are you allowed to have any sort of metallic conduit going through a wall cavity.. or is this where the buck stops for getting 80+volts dc without arc fault into my building?
 
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whether AFCI is an exception, it applies only to "output" DC circuits... which also is unclear to me. sounds like all "source" DC circuits have to be AFCI protected in a building roof-top application. ARGH. fing BS. I get it from a fire safety/prevention perspective, but trying to make any residential install legal is becoming more and more impossible, let alone cost effective. maybe someone has a standalone AFCI solution for single off-grid inverter application that is not sunspec compliant. would appreciate the guidance. I can swallow 10% added cost for RSD. but converting to micro-inverters is out of the question.

fairly helpful

so honestly... I think i'm "done" with it. FilterGuy is right... it's impossible to legally install a residential roof-mount system in a cost-effective manner. the regulations are forcing us to use micro-inverters. guess i'm now officially going "rogue". I'll run as much PV wire and MC4s in EMT as is feasible and place my parallel connectors in a grounded metal box to contain it.
 
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Microinverters are pretty nice for grid tied exporting roof systems if you want to put panels all over the place, but making them do battery backup gets up there in dollaridoos. Nice thing about them from the government/utility standpoint is they automatically narc you out the first chance they get if you install them yourself and let your power consumption drop a minute.. :)
 
I will never do grid tied. The entire point of solar, to me, is energy independence. grid tied systems are the opposite of that
 
maybe someone has a standalone AFCI solution for single off-grid inverter application that is not sunspec compliant. would appreciate the guidance.
The Fonrich options that we were talking about above is promising - @jesse_c bought some, so we'll see how it goes. I'm interested in both a Ground Fault and Arc Fault solution for my String Inverter Configuration.

I just got my system up and running but don't have check in either of those boxes as of yet. I also need to finish my rapid shutdown solution, since I only have it in place for the panels, but nothing to prevent the inverter from backfeeding to the roof.
 
Sounds like metallic raceways under PV panel junction boxes to hold the wires (but not metallic conduit between junction boxes?) and no AFCI required, even for panels on residential rooftops.

Does a similar clause apply to RSD?
 
Does a similar clause apply to RSD?

Not that I’ve read. That only states system voltage has to be below 80v within 3ft of array in the event of initiating shutdown (don’t quote me, just going off the top of my head). Nothing about raceways or conduit.
 
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