Well, mostly I was trying to say that there's one section that requires a service disconnect (in Article 230), another that requires a PV rapid shutdown initiation device (in Article 690), and another that requires an ESS shutdown device (in Article 706).
I don't mean to say that a single device can't perform more than one of those functions, but I don't see the language in 690.12(C) as allowing rapid shutdown initiation for a single PV system to be accomplished by more than 1 action (e.g. throwing two switches). If you have multiple PV systems (multiple inverters, say), each one could have its own rapid shutdown initiation device, to my reading.
(2020) 706.15(A)'s language is a bit less clear, but it does refer to "the" disconnect for an ESS. [Apparently 705.16(A)'s language about a readily accessible ESS disconnect outside the building for one and two family dwellings is new for 2020?]
Cheers, Wayne
I only had really reviewed 2017 code to this point on rapid shutdown, but the below discussion isn't specific to this job.
Loss of AC (grid) power is typically accepted as a means of PV rapid shutdown but when you have a battery then there may be an instant or delayed reconnection of the PV when the island is created. I would try to argue that eliminating the multiple sources of power calls for disconnecting each one, though I might lose lol. When there are 2 other sources of power like an ESS and grid this seems reasonable for there to be 2 switches. I see the 2017 RSD code doesn't have the same 2020 language that says it must be a single switch for a single PV system, so my argument gets really bad Jan 1.
The 2020 NEC 690.12.C does start off that "The initiation Device(s) shall initiate rapid shutdown function of the PV system." So it is clear multiple devices are allowed. However, the later sentence (new to 2020) seems to imply that this must be a single switch "For a single PV system the rapid shutdown shall occur by the operation of any single initiation device. Devices shall consist of at least one or more of the following: 1. Service Disconnecting Means 2. PV System Disconnecting means 3. Readily accessible switch that plainly indicates in the on or off position.
As far as the new section of
706.15(A) there was no requirement in 2017 to have an exterior ESS disconnect for 1 and 2 family dwellings, so that part is all new.
When talking about the ESS disconnect, we have to talk about multiple disconnects since that is the way the NEC defines ESS. 706.2 says that an ESS is one or more components assembled together. The Tesla Powerwall 2 AC, is AC coupled multimode system with up to 10 ESS components possible. The 30A breaker for each Powerwall is the ESS disconnect, and the disconnect feeding the TEG on the grid side is the Interactive system disconnect.
I do not think the 2020 code intends that I provide a single breaker where someone could turn off every of the ESS on the exterior of the building with a single switch. However it would be quite confusing if I placed single Powerwalls all around the building, with a separate disconnect next to each of them and no other obvious way to shut all of the ESS down, though it may be code compliant. To make matters worse, the Tesla Powerwall signal light doesn't obviously change colors or flash rapidly or anything when it is shutdown. Firefighters hate that! How do they know they found and turned off 5 batteries assuming they arent grouped and the lights do not change regardless?
It's clear that the fire service has a part to play here as emergency responders and they unfortunately get input later, or not at all. My design practice is to always use the fewest switches possible and less than 6, group them together and put disconnects at or in sight of the service wherever possible. I prefer using the battery disconnect button to make an easy shutdown procedure for the first responders whenever possible (hit the button and turn off the main in any order). However if someone accidentally presses it while the grid is down, it is usually a service call to 12v jump the system and wake it up. For whatever reason people often bump the button or maybe they press it because they can't help themselves.
Ah, disconnect discussions are some of my favorites, I guess I have a lot to say about this lol.