[RE-wrenches] Rapid Shutdown for Off-grid systems
Ray
ray at solarray.com
Tue Feb 1 22:24:42 EST 2022
PV System Disconnect, not RSS
Ray Walters
Remote Solar
303 505-8760
On 2/1/22 7:04 PM, Jeremy Rodriguez wrote:
> Just a rated disco at the ground mount? Labeled as the rapid
> shutdown switch?
> That’s too simple!
>
> In
>
> Jeremy Rodriguez
> Solar Installation / Design Expert
> All Solar, Inc.
> 1453 M St
> Penrose Colorado 81240
>
> Sent by Jeremy's iPhone. Sorry for typos and shorthand.
>
>> On Feb 1, 2022, at 6:49 PM, Lloyd Hoffstatter
>> <lloyd at sunstruckconsulting.com> wrote:
>>
>>
>> We’ve used multi-pole rated disconnects at the array.
>> Best regards,
>> Lloyd
>>
>> Lloyd Hoffstatter
>> Sunstruck Consulting
>>
>> Get Outlook for iOS <https://aka.ms/o0ukef>
>> ------------------------------------------------------------------------
>> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on
>> behalf of Jeremy Rodriguez <allsolarjeremy at msn.com>
>> *Sent:* Tuesday, February 1, 2022 8:31:16 PM
>> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
>> *Subject:* Re: [RE-wrenches] Rapid Shutdown for Off-grid systems
>> What about the PV circuits that leave the combiner and are ran on or
>> in a building to the CC
>>
>>
>>
>> Jeremy Rodriguez
>> Solar Installation / Design Expert
>> All Solar, Inc.
>> 1453 M St
>> Penrose Colorado 81240
>>
>> Sent by Jeremy's iPhone. Sorry for typos and shorthand.
>>
>>> On Feb 1, 2022, at 4:07 PM, Brian Mehalic <brian at solarenergy.org> wrote:
>>>
>>> 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 <bbassett2 at gmail.com>
>>>> 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
>>>> <brian at solarenergy.org> 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
>>>>> <william at 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 <http://www.millersolar.com/>
>>>>>
>>>>> CA Lic. 773985
>>>>>
>>>>> *From:*RE-wrenches
>>>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf
>>>>> Of *Ray
>>>>> *Sent:* Tuesday, February 1, 2022 10:11 AM
>>>>> *To:* re-wrenches at 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 <http://www.millersolar.com/>
>>>>>
>>>>> CA Lic. 773985
>>>>>
>>>>> *From:*Jay [mailto:jay.peltz at gmail.com]
>>>>> *Sent:* Tuesday, February 1, 2022 6:07 AM
>>>>> *To:* william at 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
>>>>> <william at 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 <http://www.millersolar.com/>
>>>>>
>>>>> CA Lic. 773985
>>>>>
>>>>> *From:*Jerry Shafer [mailto:jerrysgarage01 at 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
>>>>> <william at 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
>>>>>
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