Change in 2023 NEC code around PV arc fault.

[Hedges]

"FWIW, the intent of the 2020 code (and by my read the 2023 code, but equally poorly written) is to requrire the PV wiring *within the occupied structure* to be in metal conduit or raceways..."

I agree.

I could agree with putting it in conduit to reduce chance of arc starting a fire in the house.
But I think if a DC PV wires does arc in the conduit, it can burn through it and just keep arcing.
I use a buzz box for arc welding and have difficulty not burning right through thin tubing.
Most residential PV is lower current than most arc welding, but higher voltage and similar wattage. Maybe that means easier to sustain the arc (especially with DC), and same power delivered to metal "workpiece"

We'll probably get decent arc fault at reasonable cost integrated in most future equipment. All the newer US model GT PV inverters have it. Expect it for UL listed AIO, but there will be a market beside residential. SCC probably slow to follow, smaller market not on houses or not inspected. Midnight has it, don't know if any others.

 

[rhino]

Was thinking about this more and some preventative design I think would be to use XHHW wire instead of THWN which I've seen some people use. The XHHW insulation is far superior to insulation used for THWN and therefore less likely to have insulation related issues that may cause arc fault.

 

[SniperX]

"FWIW, the intent of the 2020 code (and by my read the 2023 code, but equally poorly written) is to requrire the PV wiring *within the occupied structure* to be in metal conduit or raceways..."


I could agree with putting it in conduit to reduce chance of arc starting a fire in the house.
But I think if a DC PV wires does arc in the conduit, it can burn through it and just keep arcing.
I use a buzz box for arc welding and have difficulty not burning right through thin tubing.
Most residential PV is lower current than most arc welding, but higher voltage and similar wattage. Maybe that means easier to sustain the arc (especially with DC), and same power delivered to metal "workpiece"

We'll probably get decent arc fault at reasonable cost integrated in most future equipment. All the newer US model GT PV inverters have it. Expect it for UL listed AIO, but there will be a market beside residential. SCC probably slow to follow, smaller market not on houses or not inspected. Midnight has it, don't know if any others.

Does a Schneider system have arc fault protection built in their PV charge controllers? I am starting to investigate that system.

 

[zanydroid]

I think Schneider, MidNite, and Outback each have a mix of pre- and post-AFCI requirement hardware still in their sales catalog. So you need to be sure you buy the right iteration.

 

[pvgirl]

Does a Schneider system have arc fault protection built in their PV charge controllers? I am starting to investigate that system.

It's not built in, the MPPT Disconnect RS add on is required to get arc fault and rapid shutdown.

 

[400bird]

It's not built in, the MPPT Disconnect RS add on is required to get arc fault and rapid shutdown.

Yup, this is also how they integrate RSD
Here's a link for SniperX

MPPT Disconnect RS

El MPPT Disconnect RS es un accesorio para los controladores de carga Conext™ MPPT, que proporciona un cumplimiento simplificado del NEC 2017.

solar.se.com

 

[SniperX]

Thanks everyone!!!

 

[cs1234]

It's $1000 for the Remote Switch and Disconnect just to add arc fault and rapid shutdown ability, not counting the needed Tigo modules. The more things I see in this industry, the sadder I become.

I might not have many nice things to say about SignatureSolar, but at least they are working towards lowering prices in general while selling code compliant equipment. Somebody sure as heck needs to do so.

 

[Shimmy]

It's $1000 for the Remote Switch and Disconnect just to add arc fault and rapid shutdown ability, not counting the needed Tigo modules. The more things I see in this industry, the sadder I become.

I felt the same way at first, and it kind of moved me away from Schneider as a solution. That said, it really comes down to how you value safety. We are all willing to take chances on things we think are a low probability of occurring, but we have poor tools to assess that probability. For me, I look at the stuff on the roof as generally needing to be set-and-forget for 15+ years. Looking at my installation which was done professionally 8 years ago... we weren't there then and we are only a little better today.

Ultimately though Schneider needs to update their charge controllers to integrate RSD, GFI, Arc Flash, and powerline communications for RSD. It might add 20% to the charge controllers, but the real savings is in limiting part count while maintaining flexibility. If they don't, the AIOs will eat them for lunch.

 

[Quattrohead]

If they don't, the AIOs will eat them for lunch.

They already are. The Solark 15k and EG418k both do everything that you would want a unit to do and are easy to install, not too bad to configure and price efficient. The only thing the 6848 has going for it is the absolutely incredible capacity overhead it has. Basically I see it as a power inverter and nothing more.
And I just saw the announcement at luxpower have integrated with tigo monitoring, this is becoming a One-Stop shop plug and play.

 

[SniperX]

They already are. The Solark 15k and EG418k both do everything that you would want a unit to do and are easy to install, not too bad to configure and price efficient. The only thing the 6848 has going for it is the absolutely incredible capacity overhead it has. Basically I see it as a power inverter and nothing more.
And I just saw the announcement at luxpower have integrated with tigo monitoring, this is becoming a One-Stop shop plug and play.

If you were Off-grid, the panels were mounted on the ground, and money was not a factor, which would you purchase? I haven't seen much in the way of Solark 15k tested against a Schneider 6848 but I have seen the Solark 12k against the 6848. Is the different-sized MPPT pv inputs on the 18kpv limiting with the larger panels in the 450W range? I am at a crossroads here...

 

[Shimmy]

If you were Off-grid, the panels were mounted on the ground, and money was not a factor, which would you purchase? I haven't seen much in the way of Solark 15k tested against a Schneider 6848 but I have seen the Solark 12k against the 6848. Is the different-sized MPPT pv inputs on the 18kpv limiting with the larger panels in the 450W range? I am at a crossroads here...

If money (and space) was not an issue I would get two 6848's over the SolArk or EG4 for reliability. When it comes to flexibility with different operating modes I don't think there is a clear winner yet.

 

[CoolWill]

I don't think there's a difference in the 2020 vs. 2023 codes besides wording.