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 <ll...@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-boun...@lists.re-wrenches.org> on behalf of Jeremy Rodriguez <allsolarjer...@msn.com>
*Sent:* Tuesday, February 1, 2022 8:31:16 PM
*To:* RE-wrenches <re-wrenches@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 <br...@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 <bbasse...@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 <br...@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
    <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 <http://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 <http://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 <http://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

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