Sorry, forgot to state my previous comment was in regards to a ground-mount.
Brian > On Feb 1, 2022, at 12:19 PM, William Miller <will...@millersolar.com> wrote: > > > Ray: > > Thanks for that input. I was hoping I was wrong. I looked for that > discussion in the archives but could not find it. > > William > > Miller Solar > 17395 Oak Road, Atascadero, CA 93422 > 805-438-5600 > www.millersolar.com > CA Lic. 773985 > > > From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On > Behalf Of Ray > Sent: Tuesday, February 1, 2022 10:11 AM > To: re-wrenches@lists.re-wrenches.org > Subject: Re: [RE-wrenches] Rapid Shutdown for Off-grid systems > > Ground mounts do NOT require RSS. We hashed this out years ago on the > Wrenches list, when NEC 2017 came out. > > See Figure 690.1(B) Note (2): " The PV system disconnect in these diagrams > separates the PV system from all other systems". > > Thus, the PV disconnect is defined as the transition point from the PV system > to all other systems, like battery or inverter systems. The installer/ > designer decides where to put that disconnect. I usually put it on the wall > before it goes into the building, and I have never had an inspector question > that. > > Thanks, > > Ray Walters > Remote Solar > 303 505-8760 > On 2/1/22 10:06 AM, William Miller wrote: > Jay: > > Here is the text from 2017: > > 690.12 Rapid Shutdown of PV Systems on Buildings. PV > system circuits installed on or in buildings shall include a rapid > shutdown function to reduce shock hazard for emergency > responders in accordance with 690.12(A) through (D). > > Exception: Ground mounted PV system circuits that enter buildings, of > which the sole purpose is to house PV system equipment, shall not be > required to comply with 690.12. > > The wording is interesting. The requirement is directed at “PV system > circuits…”, not PV arrays. The passage does not specify where the PV feeding > those circuits is located, it just addresses where the circuits are, > specifically “in or on a building.” > > The only circuits that are exempt are those feeding a building that serves > only one purpose, to house PV equipment. For circuits that enter building > with other uses—homes, garages, barns, workshops, etc.-- it would seem there > is a requirement to have rapid shutdown systems (RSS). > > Reading through the rest of the section, I don’t see any language that gets > us out of the requirement to reduce voltages to less than 80 volts within 30 > seconds inside the array boundary, as in module level shutdown, regardless of > roof-top or ground-mount. Although the 2020 code includes some differing > language, I don’t see it as exempting ground mount systems. > > The moral of the story is this: For ground-mounts: either install RSS or > put your equipment (inverters, charge controllers, batteries, BOS) in a > separate building housing only that equipment. > > I don’t necessarily like the requirement, but I think it exists. Jay, or > anyone, please, please tell me I am reading this incorrectly. > > By the way, regarding battery circuits, here is a quote from a post by Bill > Brooks on March 16, 2016: > > In the 2017 NEC, we were very careful to carve out all batteries and loads, > that were previously part of PV systems, and place them in their own > articles. > > I have not read through the battery sections of the code to verify this, I am > taking Bill at his word. > > William Miller > > Miller Solar > 17395 Oak Road, Atascadero, CA 93422 > 805-438-5600 > www.millersolar.com > CA Lic. 773985 > > > From: Jay [mailto:jay.pe...@gmail.com] > Sent: Tuesday, February 1, 2022 6:07 AM > To: will...@millersolar.com; RE-wrenches > Subject: Re: [RE-wrenches] Rapid Shutdown for Off-grid systems > > 2017 code has a specific exception/clarification for ground mount solar that > it does not need RS. > It’s in the first line after 690.12 > > Jay > > > On Feb 1, 2022, at 12:13 AM, William Miller <will...@millersolar.com> wrote: > > > Jerry: > > Yes it is required. Rapid Shutdown: NEC 690.12. All buildings except > dedicated solar buildings. Read it and weep. > > William > > Miller Solar > 17395 Oak Road, Atascadero, CA 93422 > 805-438-5600 > www.millersolar.com > CA Lic. 773985 > > > From: Jerry Shafer [mailto:jerrysgarag...@gmail.com] > Sent: Monday, January 31, 2022 7:21 PM > To: William Miller; RE-wrenches > Subject: Re: [RE-wrenches] Rapid Shutdown for Off-grid systems > > William > Are you sure RSD is required on a non habitable building, historically its > not required. Now that being said we use fire raptor with the best results, > yes it takes an extra conduite and might require a button and power supply > depending on inverter application. > Jerry > > On Mon, Jan 31, 2022, 9:57 AM William Miller <will...@millersolar.com> wrote: > Friends: > > It is quite rare for us to install off-grid systems on roof-tops. We have > one coming up with about 20kW on a large barn roof. This will be our first > off-grid with a module-level rapid shutdown requirement. I see no exemptions > from RSS for off-grid systems in the code. I have looked at the options and > this is what I have found: > > 1. Fire Raptor > > 2. Tigo TS4-F > > 3. AC coupling with micro-inverters or optimizers > > > No one of these approaches seems ideal. The fire raptor requires extra > wiring for control leads. The Tigo requires a wireless control system which > worries me about reliability. With AC Coupling systems floating the proposed > AGM batteries may be awkward. Furthermore, with AC coupled systems one > cannot charge batteries unless the mini-grid is operational, a big problem. > > Have any of you implemented module-level RSS on a battery-based inverter > system? I looked in the archives and found no threads that apply. Thank in > advance. > > William Miller > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
