UL3741

[electrofelon]

So this seems to be getting simpler and a no brainier right? I guess all of unirac's racking systems are now 3741. All you have to do is. Select an inverter from the list and follow a few simple rules like inverter locations. See this document if you haven't and are interested.

https://unirac.com/wp-content/uploads/bsk-pdf-manager/2023/07/UL-3741-One-Pager-V7.pdf

Only thing I haven't dug into is the "wire management per instructions". Is there anything crazy in that? Anything else I am missing?

 

[electrofelon]

Hmmmm taking a closer look at that inverter list, I don't see any single phase inverters on it.

 

[letgomywago]

Hmmmm taking a closer look at that inverter list, I don't see any single phase inverters on it.

Can you ask and see if they're listing any to that standard now?

 

[electrofelon]

Oh wait those goodwe MS are 120/240 single phase.

 

[electrofelon]

...and by some miracle, the goodwe inverters meet the NYS required UL 1741 supplement B listing, so I just may be able to navigate through some red tape on this

 

[BandGap1.1eV]

Only thing I haven't dug into is the "wire management per instructions". Is there anything crazy in that? Anything else I am missing?

The wire management requirements are stupid IMO. It requires the use of plastic zip ties and disallows the use of [more robust] stainless steel module frame clips. Once UL gets over that hoop, I'll be more in favor of 3741.

 

[electrofelon]

The wire management requirements are stupid IMO. It requires the use of plastic zip ties and disallows the use of [more robust] stainless steel module frame clips. Once UL gets over that hoop, I'll be more in favor of 3741.

I don't really have a problem with zip ties as long as they are quality UV resistant ones. I mean look at overhead triplex wire, it sits out in the sun for decades no problem. Do they specify a specific zip tie to be used?

 

[BandGap1.1eV]

I don't really have a problem with zip ties as long as they are quality UV resistant ones. I mean look at overhead triplex wire, it sits out in the sun for decades no problem. Do they specify a specific zip tie to be used?

UV resistance /= UV proof and overhead wire is not subject to the annual heat fluctuations associated with a rooftop PV install. The combination of 150+ degree temperature swings plus UV exposure will often lead to premature failure.

I've inspected far too many systems that relied solely on plastic wire ties only to see them fail before year 5.

Plus it looks hack.

 

[jaggedben]

And I've seen many systems with plastic zipties that have lasted much longer than 5 years. Seems to depend highly on rather unknowable qualities of the zipties, unfortunately.

And I disagree that it looks hack. I've seen hack and non-hack with both ties and clips. I do tend to think best workmanship uses a combination since no one thing is good for every spot you need support.

 

[electrofelon]

UV resistance /= UV proof and overhead wire is not subject to the annual heat fluctuations associated with a rooftop PV install. The combination of 150+ degree temperature swings plus UV exposure will often lead to premature failure.

I've inspected far too many systems that relied solely on plastic wire ties only to see them fail before year 5.

Plus it looks hack.

Note I said "as long as they are quality UV resistant ones". The problem is there isn't any sort of product standard for these so they can put a drop of UV stabilizer in and say "UV resistant". But I would speculate the the good quality zip ties will be much longer lasting than the cheap home Depot ones.

 

[BandGap1.1eV]

And I've seen many systems with plastic zipties that have lasted much longer than 5 years. Seems to depend highly on rather unknowable qualities of the zipties, unfortunately.

And I disagree that it looks hack. I've seen hack and non-hack with both ties and clips. I do tend to think best workmanship uses a combination since no one thing is good for every spot you need support.

Using zip ties to bundle wire is fine. I'll accept that on a site. But they are not fine for mechanical support when the client is expecting a 20+ year system life. I'll almost always make the installer re-work the installation if I see zip ties supporting the wires.

 

[electrofelon]

Using zip ties to bundle wire is fine. I'll accept that on a site. But they are not fine for mechanical support when the client is expecting a 20+ year system life. I'll almost always make the installer re-work the installation if I see zip ties supporting the wires.

Seems to me like a pretty broad generalization. IF by "zipties" you mean the home depot ones, sure. But what about those quality ones that are 1/2" - 5/8" oir more wide? I'll admit they are a bit hard to find , but I dont see any reason why one of those heavy duty ones wouldnt hold up for decades. My utility has these ones that are like 3/4" wide and they use them to secure 25KV caables in their vaults.

 

[BandGap1.1eV]

Seems to me like a pretty broad generalization. IF by "zipties" you mean the home depot ones, sure. But what about those quality ones that are 1/2" - 5/8" oir more wide? I'll admit they are a bit hard to find , but I dont see any reason why one of those heavy duty ones wouldnt hold up for decades. My utility has these ones that are like 3/4" wide and they use them to secure 25KV caables in their vaults.

Zipties on a PV install screams "I didn't plan this out" or "I didn't read the drawings" or "I need to get out of here as fast as possible". Knowing that, an installer who's using zip ties will not be going out of their way to get the 1/2" wide ones.

I'd have no problem using them in utility vaults since they aren't exposed to the two killers: UV and 140 degree temperature cycles.

 

[electrofelon]

Zipties on a PV install screams "I didn't plan this out" or "I didn't read the drawings" or "I need to get out of here as fast as possible". Knowing that, an installer who's using zip ties will not be going out of their way to get the 1/2" wide ones.

I'd have no problem using them in utility vaults since they aren't exposed to the two killers: UV and 140 degree temperature cycles.

My point is just that there are good long lasting zip ties, like many things its just a matter of how much you are willing to pay, and of course for many people the 1000 ct bag at home depot seems like a good option. Again look at service drop wire, the stuff is amazing it lasts for decades in the direct sun and with big temp swings, and I dont recall ever seeing it get brittle or compromised. Make 'em out of that resin and its going to be fine.

 

[electrofelon]

Zipties on a PV install screams "I didn't plan this out"

I also want to say that the racking manufacturers (at least the ones I have used, there are many I haven't) have really dropped the ball and put pretty much zero effort or design into wire management. IT could all be so much better with some thought and effort into integral wire management.

 

[BandGap1.1eV]

I also want to say that the racking manufacturers (at least the ones I have used, there are many I haven't) have really dropped the ball and put pretty much zero effort or design into wire management. IT could all be so much better with some thought and effort into integral wire management.

This we will agree on, and IMO it's all in the name of least first cost. Whoever can deliver a less expensive system gets the job. PanelClaw does a reasonable job in the ballasted racking world, but I haven't seen many others in that space put thought into wire management. That's why use of Heyco wire clips are so important. In the rail based world, Ironridge clips and padded loop clamps do a lot of work.

I've asked Applications Engineers in the past about racking integrated wire management and most of them shrug and say "meh, means and methods".