Do i need a fancy charge controller with arc fault protection?

[Hedges]

NEC tells me that I do not need arc fault detector if my system voltage is less than 80v.

Are you sure the 80V threshold in NEC is for arc fault? (Could be, I'm slow to find such things)
I recall 80V being a number for rapid shutdown, getting into shock hazard territory.

80V, 50A should be plenty to draw a nice arc and start a fire, so I would expect a wattage limit.

 

[Wellbuilt]

Outback flexmax is a very high end controller, the one big drawback for me on this one is programmer is a must to set many of the settings necessary. I picked the Midnight as no remote programmer is needed, its all on board. Every setting or thing to be monitored can be done from the front panel. Both of these controllers were designed by the same teams, both companies are started by Robin and boB Gudgel, they are also the founders of Trace Engineering.

I see the evolution of design over the years, the Midnight is the latest and best from the Gudgels, Arc Fault and Ground fault built in, no expensive ground fault breaker required as in the Outback. No need to use your phone to program, RJ-45 port for remote monitoring or programming built in , accessible from online,

Do get the built in display, its not elegant, just very practible, no whistles, bells, fancy display.....down to the brass tacks, you can get any data you need or set any variable from here, very valuable when things go to hell

The Midnight lineup is expanding, there are inverters in the chute right now that hopefully be available this year
Yes, they are expensive, but the reliability is not matched anywhere

In all honesty I do need to admit that I am a Midnight beta tester, but that does not bias my opinion of equiptment,
I have always liked the best of electronics, I have a stack of that legendary Bob Carver stereo gear, some over 20 years old and cant be beat no matter the cost, did a whole career in electronics/electrics from DC to 12 Ghz

I like mid nite stuff and would of went with them if they could provide a whole system .
My out back fm 80 can be programmed from the front panel ? That’s how I work it now .
I can set it thru the mate if I want to .
The inverter needs the mate to change setting s
I think there is a ground flat breaker in my panel and the arc fault ie in the fm 100 I believe .
I would rather just stay all out back if possible .
I sure do appreciate your time .

 

[Roswell Bob]

Are you sure the 80V threshold in NEC is for arc fault? (Could be, I'm slow to find such things)
I recall 80V being a number for rapid shutdown, getting into shock hazard territory.

80V, 50A should be plenty to draw a nice arc and start a fire, so I would expect a wattage limit.

I'm not sure of anything when it comes to NEC. I think they introduce a certain amount of vagueness when writing these standards. Vagueness may be the lubrication that keeps their machine running. In any case I don't want to burn my place down so I try to follow their guidelines.

 

[A.Justice]

I'm not sure of anything when it comes to NEC. I think they introduce a certain amount of vagueness when writing these standards. Vagueness may be the lubrication that keeps their machine running. In any case I don't want to burn my place down so I try to follow their guidelines.

I think it's left intentionally vague to leave it up to local inspectors for interpretation. I see the NEC as more of a framework than a rule book.

 

[Wellbuilt]

The biggest problem I see is the frame work is changing rapidly in my area and the rules are changing all the time .
When I started the inspectors did not know how to proceed now they are talking all kinds of silly nonsense

 

[Roswell Bob]

Outback Solar does make a Arc Fault unit that can be added to your existing system. Only one is needed as it will protect multiple Outback SCC’s. This is totally acceptable to the code.

There are also Ground Fault breakers that can be added to your system as older Outback units do not have Ground Fault built in.

Midnight Solar does have such a breaker that can be used with Outback Solar SCC’s This is also acceptable to the NEC

Ground mount solar array’s do not need a rapid disconnect, that is only required on a building.

If you do need to upgrade your system Midnight Solar has designed both Arc Fault and Ground fault into the Midnight Solar Classic controllers.

There are some limited Midnight Solar Classic models that do not have Arc Fault or Ground Fault, These were built for a limited application and are available in the surplus market and are not suitable where Arc Fault and Ground Fault are required

My panels are on the back side of the roof they where burred in snow for 10 weeks last winter
the only place I could place panels is on the left /bottom of the pic .
My drive way runs down along that area .
Its about 900 and the shadows would be running across the array .
it would be ok in the winter but summer time there are a ton of trees .
I have 24 295 watt panels with the fancy controller I could run 6in series 4 in parallel and run down the left side of the house but it would be nice to leave the equipment on the roof
I want a garage on the right side in the back so I could put the equipment in there ?
If the fire men show up it would have to be in a helicopter
View attachment 71287

 

[Tecnodave]

AFAIK......Arc fault and Ground fault is required in the code, it is an automatic red tag here, as is rapid disconnect in most situations.

Here in CA , if you do not have rapid shutdown, and rapid disconnect most firefighters will not risk their lives, better to let your insurance company pay out than to bury a firefighter......

 

[Roswell Bob]

AFAIK......Arc fault and Ground fault is required in the code, it is an automatic red tag here, as is rapid disconnect in most situations.

Here in CA , if you do not have rapid shutdown, and rapid disconnect most firefighters will not risk their lives, better to let your insurance company pay out than to bury a firefighter......

AFAIK......Arc fault and Ground fault is required in the code, it is an automatic red tag here, as is rapid disconnect in most situations.

Here in CA , if you do not have rapid shutdown, and rapid disconnect most firefighters will not risk their lives, better to let your insurance company pay out than to bury a firefighter......

Yes, it is plain as day that arc fault protection is required in most applications. I'm leaning towards the Midnite Solar Classic 200. I'm switching over from lead acid and just don't trust the Make Sky Blue units I have considering the investment in the new cells, and the possibility of burning the ranch down. Yes, our firefighters are very valuable. They pulled my daughter and her 5 roomates out of a burning house after a night on the town. Thank you.

 

[JJJJ]

I have been following this discussion on a number of threads. I have the Victron Multiplus. However my understanding is that they recommend an external separate ground fault which as I understand it is a separate issue from arc fault.

There supposedly are combiner boxes that promise both ground and arc fault, but I have yet to see them readily available. Perhaps if I looked more?

In the meantime, I am intrigued that the Morningstar MPPT seems to have both. My goal is safety first. My question is anyone out there combining the Morningstar MPPT with the Victron Multiplus?

 

[Halfcrazy]

We are in similar boat. Been building house for 5 years - a little at a time. Now need CO.

I am using Make Sky Blue charge controllers and looking at swapping them out. I am wondering if putting charge controllers outside and bringing in 48v gets under the NEC 80v requirement. I have

I am running a pair of 2kW arrays with independent charrge controller on each array. I would need 2 of the Midnight Classic at about $700 each. What charge controller are you looking at?

be careful with that, Charge controllers like short battery cables the batteries absorb the switching ripple and make the battery capacitors life easier. Long cables will cause that to be more pronounced

 

[JJJJ]

On a related note, I have wondered if going the other direction would help. Granted using higher amps requires larger wires. However if one shifted from volts to amps (more in parallel) this could potentially bypass this requirement if I understand it correctly. (perhaps not?)

 

[Hedges]

I have been following this discussion on a number of threads. I have the Victron Multiplus. However my understanding is that they recommend an external separate ground fault which as I understand it is a separate issue from arc fault.

There supposedly are combiner boxes that promise both ground and arc fault, but I have yet to see them readily available. Perhaps if I looked more?

In the meantime, I am intrigued that the Morningstar MPPT seems to have both. My goal is safety first. My question is anyone out there combining the Morningstar MPPT with the Victron Multiplus?

Ground fault is trivial to implement. Unlike human safety ground fault which works at 5 mA, ground fault for PV detects > 1.0A

My early inverters had a 1A fuse between PV negative and ground. If a short happened somewhere, the fuse would blow and inverter, upon seeing voltage between PV negative and ground, shuts down.

In a combiner box I've seen an 0.5A breaker between PV negative and ground, ganged to PV breakers. If current trips the 0.5A breaker it disconnects the PV array.


Arc fault is far more difficult because it has to the the RF signature of an arc, with signal strength 1000's of times lower than switching harmonics of the MPPT circuit. While ignoring radio signals picked up from the air.

I think arc-fault has been implemented in grid-tie inverters, so not much market for stand-alone devices anymore.
There were stand-alone arc-fault devices including Sensata PVAF, but I'm not seeing for-sale listings anymore.
I picked up a couple when they were on eBay for my future use.

https://static6.arrow.com/aropdfconversion/1e84fa017283d15e2d3fda3ed5ba7cbe439128e1/245pvaf-t.pdf

Arc Fault Combiner Box

www.connectpv.com

Peerless Electronics Stocking Sensata Solar Arc Fault Detectors - Solar Industry

Bethpage, N.Y.-based distributor Peerless Electronics says it is stocking the Sensata PVAF family of solar arc fault detectors. The PVAF family is a series of arc detection systems for use in inverters or combiner boxes on new arrays or for retrofit boxes on existing arrays. The systems enable...

solarindustrymag.com

Midnight Classic has arc-fault (and ground fault), so that may be a good way to get those features in a DC coupled system.

MidNite Solar Inc. - THE MIDNITE CLASSIC:<BR/>NORTH AMERICA'S MOST SOPHISTICATED MPPT CHARGE CONTROLLER

MidNite Solar is the industry leader and manufacture of quality Renewable Energy System electrical components and E-Panels.

www.midnitesolar.com

The last piece of protection is rapid shutdown. It is primarily pushed for fireman safety, but I think it would also stop arcs if they continue even though arc-fault shut down the inverter.

 

[A.Justice]

In a combiner box I've seen an 0.5A breaker between PV negative and ground, ganged to PV breakers. If current trips the 0.5A breaker it disconnects the PV array.

How does the smaller breaker disconnect the rest of the array?

 

[Hedges]

How does the smaller breaker disconnect the rest of the array?

ganged to PV breakers. If current trips the 0.5A breaker it disconnects the PV array.

"Ganged", a pin through the handles, for common trip.

I just saw a picture in someone's posting with that. It had 3 poles, one was 0.5A for ground-fault, one was for PV string, one for something else.
Should work for up to whatever number of poles are able to common-trip.

But this may not work if SCC makes another ground connection. I think some simply wire PV negative to battery negative. Even if battery negative itself wasn't grounded, bad things could happen (to someone who touches the battery) with such a design unless two poles were use to isolate PV- as well as PV+.

 

[wmgeorge]

I do not have my 2020 NEC code book close by but you can get around the Ark Fault on over 80 vdc by running it in metal conduit. Be sure to check that yourself.

 

[A.Justice]

"Ganged", a pin through the handles, for common trip.

I just saw a picture in someone's posting with that. It had 3 poles, one was 0.5A for ground-fault, one was for PV string, one for something else.
Should work for up to whatever number of poles are able to common-trip.

But this may not work if SCC makes another ground connection. I think some simply wire PV negative to battery negative. Even if battery negative itself wasn't grounded, bad things could happen (to someone who touches the battery) with such a design unless two poles were use to isolate PV- as well as PV+.

Thank you, I guess I didn't really know what the definition of "ganged" was, and didn't realize you could do it over separate breakers. Good to know.

 

[Tecnodave]

Midnite Solar does sell a “ganged” ground fault breakers that is made by Carlingswitch or CBI. These do use a .5 to 1 amp breaker in the neutral to ground connection between the system neutral and earth ground . This low current breaker is common tripped with the solar panel breakers, both positive and negative to provide ground fault protection with most any system.

Please Note.....This provides GROUND FAULT protection of the system as a whole but does not detect ARC FAULT.

Some Controllers will now have Arc Fault built in as it is now required in the code in most instances...ESPECIALLY....for an array on your roof of a dwelling.

 

[Roswell Bob]

be careful with that, Charge controllers like short battery cables the batteries absorb the switching ripple and make the battery capacitors life easier. Long cables will cause that to be more pronounced

Good point. I worked on a proposal for a 30kW charger for the Navy. They were very concerned with ripple current. I still don't fully understand why. It was some kind of lithium chemistry.

I went for a Midnight Classic controller because of the arc fault. The system is in an underground concrete bunker and I may have been able to reason away the arc fault, but I think it is a good idea to have. It will be a few feet from battery array. I'll go for another in the fall for the second array. I only need the second array running in the winter.

 

[JJJJ]

I was amazed at the photos I saw online of the damage that can happen to an inverter charger from an arc fault.

I also appreciate the concept of possible versus probable. This is how actuary tables are designed for insurance purposes.

Having said that, if some type of damage or wiring irregularity possibly happens outside at the panel side, then this poses a possible risk factor. Chances are it won't happen. However if a squirrel for instance decides to bite a wire looking for nesting material, things could potentially get interesting. Just an example.

I personally find it frustrating that more major vendors are not getting on board with this. After all it is code. I appreciate it might increase their costs and perhaps that is the reason they don't have it?

 

[Shimmy]

I do not have my 2020 NEC code book close by but you can get around the Ark Fault on over 80 vdc by running it in metal conduit. Be sure to check that yourself.

Only true if the circuits are not in/on a building, with the exception of a building used solely for PV equipment.