Help running DC PV wires in home. 2 questions.

Hello,

I plan on having a ground array in my yard and next to the ground array frame I'll have a combiner box just in case I want to add another array in the future. From my combiner box I'll be running properly sized THHN underground at least 18 inches deep in schedule 40 pvc conduit. From there I'll run schedule 80 conduit vertically up the side of my brick house. I'll have a junction box at the top of this vertical conduit, right before the wires goes into my house soffit and attic. From the outside PVC junction box I'll run flexible metal conduit up, into my attic and then across my attic to right above my electrical panel and 6000xp. I plan on running the flexible metal conduit down INSIDE of the wall and pop it out inside a wire trough that will be located right below by 6000xp. Getting the flexible metal conduit in the wall might be the tough part but I think I'll like having it hidden in the wall.

I thought I heard somewhere that I need high voltage DC PV wires in metal conduit when they are inside my home... so that's currently what I'm planning on doing. I plan on running THHN the whole way...I've already purchased it.

2 Questions,

1) Do you have any recommendation changes on the wiring as explained above? I can't really think of a better way to do it. THHN wire already purchased.

2) Do you know where in the NEC 2023 or 2020 code book it mentions high voltage PV wire needs to be in metal conduit when inside a structure? I've search the code book and I can't find that section.

Thanks.

NEC 690.31 (D)(1)

Don't forget a "readily accessible" PV disconnect means.

We're allowed to use Schedule 80 PVC instead of EMT attached to the outside of the building? I thought we could only use PVC for the elbow or a foot or so up from the ground before we have to convert to EMT? Is it because it's brick?

cs1234 said:

We're allowed to use Schedule 80 PVC instead of EMT attached to the outside of the building? I thought we could only use PVC for the elbow or a foot or so up from the ground before we have to convert to EMT? Is it because it's brick?

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It is my understanding that if its being ran to the disconnect means at the point of entry, its the exception. I have done this with AHJ inspectors, and they have passed it no problem.

690.31(D)1 - Exception: PVHCS installed in accordance with 690.12(B)(2)(1) shall be permitted to be provided with or listed for use with nonmetallic enclosure(s), nonmetallic raceway(s), and cables other than Type MC metal-clad cable(s), at the point of penetration of the surface of the building.

seneysolar said:

NEC 690.31 (D)(1)

Don't forget a "readily accessible" PV disconnect means.

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I will have 2 "ready accessible" PV disconnect options. One will be the shutoff switch in the solar combiner box(Near the solar array) and the other is the PV disconnect switch built into the 6000xp... Hopefully those 2 options will be enough.

ElkPicture said:

2) Do you know where in the NEC 2023 or 2020 code book it mentions high voltage PV wire needs to be in metal conduit when inside a structure? I've search the code book and I can't find that section.

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Note there are FMC specific rules about protection, down in 690.

zanydroid said:

Note there are FMC specific rules about protection, down in 690.

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Thanks, Found it in 690.31(D)1. Thanks @senseySolar.

seneysolar said:

It is my understanding that if its being ran to the disconnect means at the point of entry, its the exception. I have done this with AHJ inspectors, and they have passed it no problem.

690.31(D)1 - Exception: PVHCS installed in accordance with 690.12(B)(2)(1) shall be permitted to be provided with or listed for use with nonmetallic enclosure(s), nonmetallic raceway(s), and cables other than Type MC metal-clad cable(s), at the point of penetration of the surface of the building.

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Do you think I need a PV disconnect switch on the brick as the solar enters my house? I'll have PV disconnect switches in the solar combiner box and also one the 6000xp.
Thanks.

ElkPicture said:

Do you think I need a PV disconnect switch on the brick as the solar enters my house? I'll have PV disconnect switches in the solar combiner box and also one the 6000xp.
Thanks.

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I am not sure about the physical disconnect.

You will need RSD trigger though accessible from the outside. Which can be a control wiring trigger.

RSD may still leave voltage from the inverter or grid depending on how the inverter isolates, and you should not trust it for servicing.

zanydroid said:

I am not sure about the physical disconnect.

You will need RSD trigger though accessible from the outside. Which can be a control wiring trigger.

RSD may still leave voltage from the inverter or grid depending on how the inverter isolates, and you should not trust it for servicing.

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RSD is not required for ground mounts

ElkPicture said:

Do you think I need a PV disconnect switch on the brick as the solar enters my house? I'll have PV disconnect switches in the solar combiner box and also one the 6000xp.
Thanks.

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Thats up to you and the inspector. Not all combiner boxes qualify if they dont break the positive and negative. The ones built into AIO units typically do qualify, unless its not "readily accessible" and that is open to interpretation.

Generally speaking i do a Combiner box at the array, and disconnect before entering the house. If not next to the meter/ main service disconnect, i put a label there stating its location.

seneysolar said:

RSD is not required for ground mounts
View attachment 219840

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The way I read that is rsd is not required for ground mounts where the PV circuits enter a building who's sole purpose is a powerhouse?

Brucey said:

The way I read that is rsd is not required for ground mounts where the PV circuits enter a building who's sole purpose is a powerhouse?

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That is how I read it as well.

Brucey said:

The way I read that is rsd is not required for ground mounts where the PV circuits enter a building who's sole purpose is a powerhouse?

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Well, my local inspectors only care about rsd if its on a rooftop. I dont know of anyone installing rsd devices on ground mounts nor have i ran across any in the field. They are happy with a disconnect.

Edit: Perhaps the workaround is being a single array with a disconnect-

So I asked specifically about this just to make sure and the inspector sited this note at the bottom of 690.12 (which admittedly i breezed right over)
He explained the "intent" for RSD is for roof mounted panels and the fire department being able to disable all of them with 1 switch.