This update, two more racking manufacturers join the fold! Both EcoFasten and TerraGen have been added to the site, and there are interesting things to discuss about both. Let’s get into it.
First, let’s talk about TerraGen, because they’re actually the most overdue to be added to the website. Until I discovered Pegasus’ listing, I hadn’t been looking at CSA Group for UL 3741 listings – just about everyone’s listings were through Intertek. However, while Pegasus made the splash recently for having no approved vendor’s list, allowing any inverter or SID listed to 1741 to be used, they were not the first ones to achieve that goal. That prize goes to TerraGen, back in March of this year.
All of TerraGen’s rackings, TGR, TGT and TGP, are listed with any electrical equipment or inverters certified to UL 1741. More importantly, it’s extremely clear that this is how they’re listed. Their installation addendum explicitly calls this out in their Approved Components section, which is a contrast to Pegasus’ fairly confusing method of simply not specifying any inverters or SIDs (aside from mentioning specific instructions if using Tesla equipment). Here’s the exact wording:
- Approved electrical equipment / Inverters that:
- Are UL 1741 listed
- Must have PVRSS/PVRSE functions certified by UL 1741
- Follow the installation locations and guidance of this addendum
This seems to me to fulfill the requirement of UL 3741 that says the devices associated with the PV Hazard Control System must be identified. Pretty neat. This seems to be a pioneering move by the CSA Group laboratories, in particular. Schletter seemed to get their listing with CSA before CSA started taking this tactic, but there’s a pattern brewing now, with first TerraGen, then Pegasus, relinquishing the micromanagement of specific inverter/SID testing.
EcoFasten also joins us, with ye olde, time-tested method of approving specific devices for their ClickFit and RockIt rackings. They’ve listed Tesla Powerwalls and inverters, plus Tesla’s MCI-1, but added another contender to the UL 3741 ranks, MidNite Solar’s MNSSR-600S-SS, paired with Solis inverters.
It’s a string isolation device, just like Tesla’s, but it’s SunSpec-enabled, meaning compatibility could be extremely easy for other inverters to adopt, since most inverters these days are listed with SunSpec MLPEs for module-level rapid shutdown. Because of this, I wouldn’t be surprised to see this device start getting quickly adopted by other inverter manufacturers, or potentially white-labeled to other brands. Either way, I’m getting excited for what might get introduced at RE+ in Anaheim this year.
Speaking of which, yes, I’ll be at RE+, so feel free to let me know if you want to meet up for a walk ‘n talk or show me some product! I won’t be updating The UL 3741 Reference until after RE+, just because I’ve got a ton of “real work” to get done between now and then.
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As a personal note, if you enjoy all this nerdery, you should keep an eye on solarboi.com. I’ve got an opinion piece about UL 3741 just burning in my soul right now, and since I’m trying to keep the updates to this site limited to giving context about the products that get added, vs industry news or opinion pieces, any of that writing will happen over on the solarboi blog. I’ve got an RSS feed there as well, if you like to keep track of things that way.
Stay shiny,
derek the solarboi
So with TerraGen I could use an inverter like the EG4 12kPV since that is UL1741 listed. What does this mean for RSD devices for the EG4 inverter? I guess I have to look up what EG4 says and if they are not 3741 listed, then that means one RSD per panel, but if they are 3741 listed possibly less RSDs needed?
You can use any inverter with any racking system. The key is whether the inverter allows for array-level shutdown for 3741, using string-level devices like the MidNite one. You’d have to check with EG4 to see if they list compatibility with the device you want to use. I know MidNite also sells an RSD transmitter, but again, check with EG4 to make sure they’re chill with it.