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

[Roswell Bob]

I am looking at different approaches to dealing with DC Arc Fault protection. I have seen some fancy charge controllers with arc fault protection, but they are very pricey. I understand the engineering required to detect arc, so not whining about price. NEC tells me that I do not need arc fault detector if my system voltage is less than 80v. I think they intend that any wiring entering the house be less than 80v for safety. One approach I believe might fly would be to put existing charge controller outside and run charger output into battery bank in basement. Another approach might be to reconfigure panels from 4s2p to 2s4p. Open circuit voltage would then be about 60v with current near 35amps. I would then need a charge controller that would accommodate near 60v to 48v. Not much headroom at panel VOC near 32v, with VMPP near 30v. I suppose I could find a pwm controller that might work with 60v in. On most days I have quite an excess of power so thought drifted to wondering what performance might be if I just hardwired panels directly to cells and run open loop. Some control would be required to prevent over charging. Any input would be appreciated. I've not paid enough attention to code and so forth and am trying to straighten that out now

 

[Roswell Bob]

Looks like panel open circuit voltage is too high to get under 80v NEC requirement. Panel (REC250PE) is near 37voc, but NEC has a 125% multiplier. Panels are ground mount 60' from house.

Possible remaining solutions:
Sensata DC Arc fault connector to open DC breakers on pv side of charge controllers & shut down inverter.
Midnight Classic MPPT charger with Arc fault - Need a pair of these expensive controllers
Remote mount existing MPPT in outside enclosure - I believe that this will meet the 80v NEC requirement as Vbat_nom=48
Bring PV power into existing concrete bunker in corner of basement - in conduit. I expect charge controllers would need to be in metal enclosure. This would be near impossible as losses (>100w/each) for charge controller too high to put in reasonable size enclosure.

Any thoughts?

 

[Wellbuilt]

I have lots of thoughts , but none of them good .
I have a out back system that I’ve hade since 2015 ive been building a house .
the house is done and I Need to get a CO and I’m realizing my system is out dated
An it needs to be brought up to code .
I need to add rapped shut down .
I did not realize the dc needs arc fault protection so it looks like I’m going to need a 1k$ charge controller
There have been a ton of changes in the last 6 years
My next issue is the inspectors have all been replaced .

 

[Roswell Bob]

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?

 

[Wellbuilt]

I have out back equipment soooo 100amp 300v fm100 .
I think this sucks .
I need rapped shut down allso my panels are on my roof .
It’s looking like a real wiring debacle .
It’s like a big Secret, I’ve been talking to some suppliers but not getting much help yet .

 

[740GLE]

You sure it’s arc fault not lightning arrestor for the PV array?

 

[Wellbuilt]

Aaaa yep , they want this , plus all the rapped shut down equipment .
I’m thinking I may be able to go back to when I took out the permits for the house and use that part of the code ?
The building sub code official and electrical under writer looked at my system as it was going in and just said it had to meet nec code ? the equipment that would meet that code is not a available any more and outbacks new solution
it very expensive every part is 1000 and I’m not sure how many parts i need yet .
The crazy thing is my place is on the top of a mountain in the middle of nowhere.
The fire dept would have to drive up in a jeep .
It’s not like there is any one to even call them ? The house would be gone before they showed up .

 

[Supervstech]

So, the array is on your home roof?

 

[Wellbuilt]

Mine is op is ground mount

 

[Wellbuilt]

I’ve been looking at the wiring detail for rapped shut down and arc fault and I’m having a real mind block
it’s looking over my head at this point , I’m hoping after some sleep it will look better .
I may remove the panels and the charge controller and just run off generator and battery’s for now .
Then deal with all this next summer or the summer after .

 

[Roswell Bob]

I have out back equipment soooo 100amp 300v fm100 .
I think this sucks .
I need rapped shut down allso my panels are on my roof .
It’s looking like a real wiring debacle .
It’s like a big Secret, I’ve been talking to some suppliers but not getting much help yet .

Aaaa yep , they want this , plus all the rapped shut down equipment .
I’m thinking I may be able to go back to when I took out the permits for the house and use that part of the code ?
The building sub code official and electrical under writer looked at my system as it was going in and just said it had to meet nec code ? the equipment that would meet that code is not a available any more and outbacks new solution
it very expensive every part is 1000 and I’m not sure how many parts i need yet .
The crazy thing is my place is on the top of a mountain in the middle of nowhere.
The fire dept would have to drive up in a jeep .
It’s not like there is any one to even call them ? The house would be gone before they showed up .
View attachment 71140

Like this 43.14.49N 71.53.56W ?

 

[Roswell Bob]

Like this 43.14.49 N 71.53.56 W ? Fire Department would have a tough time getting up here in winter.

 

[Roswell Bob]

I have out back equipment soooo 100amp 300v fm100 .
I think this sucks .
I need rapped shut down allso my panels are on my roof .
It’s looking like a real wiring debacle .
It’s like a big Secret, I’ve been talking to some suppliers but not getting much help yet .

Maybe easier if you take panels off roof and do a ground mount or a pole. I put mine on a homebrew 8" schedule 40 pipe with a trailer axle on top. The requirements are very stringent for roof mount. Quite a bit relaxed for ground mount. I am thinking arc fault may not be required if charge controllers are outside. I think batteries can be indoors, but not 100% sure. I am more certain that whole system with inverters can be mounted outside in seperate building with even less grief.

 

[Wellbuilt]

Im may have to cut down a forest so I can ground mount the panels but I still think this sucks.
I don’t really have a good clear spot for them .
I’m sinking my well pump 700 feet in to the earth this weekend and if that go’s good and I get the water pumping I’m going to start working on the solar problem .
I have 25 acres but the place is all trees .
I have a shop in the works for this summer so I may have to move everything into that building .
I have people putting solar on there roofs all around me so there has to be a way .
It’s very frustrating .
What are The coordinates to????

 

[Roswell Bob]

Im may have to cut down a forest so I can ground mount the panels but I still think this sucks.
I don’t really have a good clear spot for them .
I’m sinking my well pump 700 feet in to the earth this weekend and if that go’s good and I get the water pumping I’m going to start working on the solar problem .
I have 25 acres but the place is all trees .
I have a shop in the works for this summer so I may have to move everything into that building .
I have people putting solar on there roofs all around me so there has to be a way .
It’s very frustrating .
What are The coordinates to????

I have 40 acres on a hilltop in New Hampshire. Coordinates are my hilltop - all trees too. Take a look at it. We've been moved in about 5 years. Living in in-law apartment in walk-out basement. Selling off some gold next week to finish off upstairs. I'd bet most of the people putting panels on roof are paying big bucks with commercial outfits. I tried to save a few bucks and do it on the cheep. Might have been better off to shell out the extra bucks and have it done to code. Could have had utility electric installed for $11/ft 5 years ago - about $15,000 back then. Today they tell me it's about $25/ft. Not regretting decision to go off-grid just yet. Next lightning strike may provoke that regret.

 

[740GLE]

Ohh be glad your off grid, you wouldn't like Unitils new winter rate. +$0.28kwhr is going to have lots of unhappy people.

I dread what Eversource will release in December for their winter rates.

 

[Wellbuilt]

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

 

[Tecnodave]

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.

 

[Wellbuilt]

hi Dave , I was thinking about this charge controler from out back .
A lot of this it over my head and I know I have a problem , I’m not sure how to deal with it
when I started in 2015 a lot of this was not a issue.
It just seams like 1000s of dollars to get approved now .
all this seams silly .
To make matters worse all the guys I’ve been dealing with have been fired ?
So there are all new people to deal with .
I’m not sure how to proceed they are talking about engineer plans and design ?
im not sure how to get passed this arrrrrrrrrrrr

 

[Tecnodave]

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