[RE-wrenches] UL3741

[Brett Stigile]

My understanding of UL3741 PV hazard control is that it is another way 
to meet 690 rapid shut down requirements without MLPE.  As long as you 
can locate the inverter within the array boundary. A nice solution for 
commercial where locating the inverter on the roof is fairly easy.

I'm interested in knowing if anyone thinks this could be a solution 
(with some tweaking) in residential where locating the inverter on the 
roof is typically not an option.  Is anyone pushing to either strip the 
code of requiring rapid shut down or offering a viable alternative such 
as UL3741 has done for commercial?

Personally, I've used Tigo and AP Smart mostly without issues. They seem 
to pair well with most all in one inverters.  However, I think they are 
a huge pain with off grid systems and charge controllers.  Best to do 
ground mounts and avoid MLPE but that isn't always an option.  The only 
issue I've had so far is trying to add Tigo TS4-2F to a MidNite Hawks 
Bay where I killed the Tigos.  My take away was that it not worth the 
trouble.

Here are some links for more info on UL3741.

Mayfield Renewables has a course on it.

https://courses.mayfield.energy/offers/ZBxkwokv/checkout?_gl=1*nusd4u*_ga*OTQzNzYwNTU0LjE3MjYxMTI2MTY.*_ga_QYYWLFVGDP*MTczOTgxMzY5Ny4yLjEuMTczOTgxMzg4OC4wLjAuMA..

SMA has a lot of info on it.  See SMA link.

https://www.sma-america.com/ul3741


Derek the solarboi YouTube channel "A Bonkers Summer for Solar/UL3741 
News and Forcasting"  Gives a nice summary of the mess we are now in 
with rapid shut down MLPE.

https://www.youtube.com/watch?v=UWUoZg53o80&t=879s




---
Brett Stigile
Owner/Renewable Energy Electrician
503-317-7950
brett at oregonsunwrangler.com

Oregon Sun Wrangler LLC
CCB: 240661
License No: 66LRT
NABCEP PV Installation Professional
certification # PV 100414-008123





On 2025-02-14 18:27, Brett Stigile wrote:
> I'm enjoying the discussion on MLPE failures and wondering how do we 
> move forward away from them.  I've seen some info on UL3741 that might 
> offer the industry a way around or out of using these devices.  I've 
> heard UL3741 has good traction in the commercial space but what about 
> residential?
> 
> There is a YouTube channel by "derek the solarboi" @dereksolarboi who 
> talks about the problem and potential solution/exit strategy with a UL 
> listing.  Curious if people are following this and think we might be 
> able to get away from adding MLPE soon.
> 
> thanks