NEC 760.15(A) remote shutdown of ESS batteries

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MJSullivan56
MJSullivan56 Registered Users Posts: 42 ✭✭
edited February 2022 in PV Installers Forum - NEC, Wiring, Installation #1
Help! My AHJ is insisting that as per NEC 706.15(A), my two Fortress eFlex batteries themselves need to be de-energized during a rapid shutdown. He sites “this is how a Tesla Powerwall does it “. What can I do?
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  • MJSullivan56
    MJSullivan56 Registered Users Posts: 42 ✭✭
    edited February 2022 #2
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    I might add, I'm in Massachusetts which has adopted NEC 2020. And section 706.1 states that it applies to any energy storage system of 1kWh or greater.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3
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    What  ??
     if the batteries are "de-energized" you are blacked out.   The Inverter needs to be able support a transfer switch to disconnect from the grid, and allow your house to be an island.   This may require a new inverter and a critical loads transfer switch
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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  • MJSullivan56
    MJSullivan56 Registered Users Posts: 42 ✭✭
    edited February 2022 #4
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    Not sure how what you say is a problem. Rapid Shutdown is initiated by firefighters. They want your enflamed house to be contained: i.e. to be an island (temporarily). The 2020 code now says not only must individual PV modules be disconnected during RSD, but any ESS as well. Not sure how to satisfy this AHJ with the equipment I have. Perhaps I need a different battery that allows remote disconnect? SimpliPhi perhaps? Apparently Tesla Powerwalls have this.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #5
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    The RSS switch for the fireman would be an input to the inverter, it's the inverter that actual shuts down the array and the battery. I suspect you have a bigger issue as with NEC2020 ESS systems are required to have UL9540 certification, which certifies that the inverter and battery combination meets NEC codes, which includes what your AHJ is asking about.

    The days of any home built backup system are over with NEC2020, only UL approved systems are allowed, and this includes anything over 24V. You can only install inverter / battery combinations that have UL9540, which is a 6 figure investment for the companies involved.
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  • MJSullivan56
    MJSullivan56 Registered Users Posts: 42 ✭✭
    #6
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    Oh, my Fortress eFlex batteries are indeed UL 9450A compliant -- that was never the issue. As it is, my AHJ finally passed my setup -- I just needed to demonstrate that BOTH the inverter as well as the charge controller were able to be turned off remotely. The trick with the case of Outback Radians was to disconnect the grid power BEFORE the inspector came (i.e. the system was running on battery power) -- then the RSI/RSD works like a charm at shutting down the system (note that it won't remotely turn things back on though -- that remains a manual process which is fine by me). As a side note, the batteries apparently don't need to be "de-energized" after all.
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