For a ground mount PV system with a DC combiner, the PV source circuits are not in or on a building so RS doesn’t apply to them. And the definition of a charge controller in Art. 100 is in its relationship to batteries/storage, not really the charging source - fundamentally it’s there to protect the storage/batteries, so it’s best considered part of that system, not the PV system (and over the last several cycles nearly all references to charge control/lers have been moved out of 690).
Brian > On Feb 1, 2022, at 3:15 PM, Bradley Bassett <[email protected]> wrote: > > > "A switch, outside of the building, opening the PV circuit to the power > electronics, and functioning as the pv system disco and the rapid shutdown > initiation device, should be all that is required." > > That is what I have found most inspectors will accept, but not all. A strict > reading of the code does come to the same conclusion that William comes to, > and some inspectors will require that. The code is not very specific on where > the PV system disconnect should go. It seems to be mostly accepted to be on > the PV side of the charge control, but when I read the code strictly it seems > to me it should be on the battery side of the charge control since it is only > a PV device. Fortunately the PV side is more accepted because that makes > things much easier. > > What I'm still having trouble with is the requirement for breaking both pos > and neg legs in the PV system disconnect unless solidly grounded which most > systems are not (690.13(E)). I see that most installers do not break both > poles, but only the positive leg, which is of course easier and less > expensive. I've quoted the use of dual pole breakers when possible, but > OutBack does not really call for that always, and if you ask about their 2 > pole 300V breakers they (and Carling) don't say they can be used that way. > And if you do, you have to run the wires in opposite directions for polarity. > I've asked for clarification but have not received it yet. Then there are the > high voltage charge controls like Schneider, where often one uses the SqD > HU361, which can be wired in various ways to meet the 600V requirement. It > can be wired one pole for up to 18A Isc for PV, or up to 30A if two poles in > series, or one pos and one neg pole in the circuit. The Schneider RS Disco > does break both poles, one of the few devices that make it clear. I'm curious > what others are doing. > > Brad > >> On Tue, Feb 1, 2022 at 11:23 AM Brian Mehalic <[email protected]> wrote: >> 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 <[email protected]> >>>> 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:[email protected]] On >>> Behalf Of Ray >>> Sent: Tuesday, February 1, 2022 10:11 AM >>> To: [email protected] >>> 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:[email protected]] >>> Sent: Tuesday, February 1, 2022 6:07 AM >>> To: [email protected]; 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 <[email protected]> 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:[email protected]] >>> 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 <[email protected]> >>> 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: [email protected] >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> There are two list archives for searching. 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