UL 3741 Metal Roof

[BackCountry]

I’ve got a 600kw project in the design phase, the roof is a 1 degree slope flat roof with a standing seam material that has 2” high seams every 40” on center.

I would really like to avoid rapid shutdown; however, all of the UL 3741 solutions out there are only for TPO and built up roofs (PanelClaw, Unirac, IronRidge, Sollega). PanelClaw would likely work since the seams are north south and the east west rails clear the 2” seam; however, they say it’s incompatible.

We were looking at MetalX railless; but that isn’t UL 3741 either.

I’d do just about anything to avoid 1200 rapid shutdown MLPE’s on this job.

Anyone know of a compatible product?

 

[pv_n00b]

There are only a few 3741 listed systems and none for metal roofs. Since it would require getting a listing specifically for a metal roof and there is much less demand I doubt that we will see one any time soon. Better plan for a regular RSD system.

 

[BackCountry]

There are only a few 3741 listed systems and none for metal roofs. Since it would require getting a listing specifically for a metal roof and there is much less demand I doubt that we will see one any time soon. Better plan for a regular RSD system.

I agree. I was hoping there was some rail product out there that would be listed but none so far.

Our EE is going to try to justify it and field list it, complying with all rules (ie inverter within 1ft etc).

 

[user12345mn]

Re-pinging this thread, have you found any UL3741 solutions for flush or metal roofs?

 

[BackCountry]

Re-pinging this thread, have you found any UL3741 solutions for flush or metal roofs?

Only ballast and flat roofs.

We did manage to permit one with a metal roof using Unirac MetalX and the AHJ bought off on it, we called it out as “meets the intent of UL3741”

 

[Backwoods]

Unirac has been quietly working on getting their NXT flushmount racking 3741 approval. They had expected UL's blessing in Q1 but it now looks like it may be Q2. UL3741 requires racking to be matched with an approved inverter, so hopefully NXT's listing will include a similar lineup of inverters as their existing UL3741 ballasted options.

 

[BackCountry]

Unirac has been quietly working on getting their NXT flushmount racking 3741 approval. They had expected UL's blessing in Q1 but it now looks like it may be Q2. UL3741 requires racking to be matched with an approved inverter, so hopefully NXT's listing will include a similar lineup of inverters as their existing UL3741 ballasted options.

Great news

 

[BandGap1.1eV]

Only ballast and flat roofs.

We did manage to permit one with a metal roof using Unirac MetalX and the AHJ bought off on it, we called it out as “meets the intent of UL3741”

Did you get it approved before the install?

 

[BackCountry]

Did you get it approved before the install?

Yes absolutely

 

[solarboi]

Only ballast and flat roofs.

We did manage to permit one with a metal roof using Unirac MetalX and the AHJ bought off on it, we called it out as “meets the intent of UL3741”

That's so rad, dude, nice work!

So the current status of UL 3741 stuff is that Ironridge has their non-ballasted stuff (XR and Aire) listed with Tesla products (resi), and Chiko has their rail listed with some Solis, GoodWe, and CPS inverters (though I've heard bad stuff about build quality around Chiko, so ymmv). Like @Backwoods said, Unirac says they're close to flush mount certification too, but I don't have any details on what inverters are being listed, etc, though I'd assume the roster will look very close to their ballast mount listings. We're on the precipice of a bunch of different option.

Also, if you want to see what's currently out there, I think I finally have everything that's 3741 listed, collected on UL3741.com. I try to keep stuff as up-to-date there as possible, but if y'all find something I'm missing, let me know.