[RE-wrenches] Remote battery disconnects

[William Miller]

Esteemed wrenches:

Well if my house is on fire and the entry of fire responders is delayed for
lack of a disconnect, I choose having the disconnect. I can worry about the
charge controllers later.

Others may prioritize their charge controller over their homes…

Put a cable-tie lock in the closed position to discourage kids from messing
with it. Test it only after dark.

William

On Sat, Jan 28, 2023 at 2:32 PM William Bryce <wlbryce at pineridgeproducts.com>
wrote:

> All
>
> One thing that no one is talking about is what happens to the MPPT charge
> controllers when the Battery Disconnect trips when the charge controllers
> are under full load.
> Many will blow up. Try turning off the battery breaker on a SolaArk  when
> the charge controllers are maxed, and see if you get lucky.
>
> On Sat, Jan 28, 2023 at 3:27 PM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Jeremy:
>>
>>
>>
>> Thanks for posting the code references for those that had never looked
>> them up.
>>
>>
>>
>> Chris:
>>
>>
>>
>> What do you mean by “a disconnect for AC wiring, not specific to which
>> or both panel types”?
>>
>>
>>
>> All:
>>
>>
>>
>> Code references are handy when receiving edicts from building officials,
>> but not required, IMHO, for two reasons:  The contractor should already be
>> versed in the codes and, building departments can mandate their own
>> requirements above and beyond the code.
>>
>>
>>
>> It may seem redundant to require an AC disconnect for premise wiring as
>> well as a DC battery disconnect.  In most cases if you disconnect the
>> inverter from the batteries the AC power goes off.  However if the
>> generator is running at the time, some battery inverters can operate when
>> disconnected from batteries.  So to completely de-energize all components
>> of an off-grid home you need to disconnect the generator and the battery
>> leads.
>>
>>
>>
>> In this case the home is required to have fire sprinklers.  There is
>> pressure pump to provide flow to these fire sprinklers-- said pump being
>> powered by the inverter/battery system.  I am going to apply for a waiver
>> to remove the DC disconnect requirement on the grounds that the pressure
>> pump is essential fire suppression equipment.  Instead I will propose to
>> supply an AC disconnect (meeting all requirements for accessibility and
>> marking) that will disconnect all premise wiring except the pressure pump.
>>
>>
>>
>> By the way, I will of course be trying to apply the logic that the
>> voltage specification is for nominal battery voltage and this project
>> having a nominal 48 volt bank does not require the battery disconnect.
>>
>>
>>
>> I will let the group know what response I receive.  Regardless of how
>> this works in this jurisdiction, I think these are both valid arguments
>> worth trying in any jurisdiction requiring the battery disconnect.  Some
>> officials are amenable to dialog and negotiation and some are less so.
>>
>>
>>
>>
>>
>> William Miller
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Jeremy Rodriguez via RE-wrenches
>> *Sent:* Saturday, January 28, 2023 10:12 AM
>> *To:* cwarfel at entech-engineering.com; RE-wrenches
>> *Cc:* Jeremy Rodriguez
>> *Subject:* Re: [RE-wrenches] Remote battery disconnects
>>
>>
>>
>> 
>>
>> *2020 Code Language:*
>>
>> *480.7 DC Disconnect Methods.*
>>
>> *(A) Disconnecting Means.* *A disconnecting means shall be provided for
>> all ungrounded conductors derived from a stationary battery system with a
>> voltage over 60 volts dc. A disconnecting means shall be readily accessible
>> and located within sight of the battery system.*
>>
>> *N* *(B) Emergency Disconnect.* *For one-family and two-family
>> dwellings, a disconnecting means or its remote control for a stationary
>> battery system shall be located at a readily accessible location outside
>> the building for emergency use. The disconnect shall be labeled “EMERGENCY
>> DISCONNECT”.*
>>
>> *N **(C) Disconnection of Series Battery Circuits.* *Battery circuits
>> exceeding 240 volts dc nominal between conductors or to ground and subject
>> to field servicing shall have provisions to disconnect the series-connected
>> strings into segments not exceeding 240 volts dc nominal for maintenance by
>> qualified persons. Non-load-break bolted or plug-in disconnects shall be
>> permitted.*
>>
>>
>>
>> Jeremy Rodriguez
>>
>> Solar Installation / Design
>>
>> All Solar, Inc.
>>
>> 1453 M St.
>>
>> Penrose Colorado 81240
>>
>>
>>
>> Sent by Jeremy's iPhone. Sorry for typos and shorthand.
>>
>>
>>
>> On Jan 28, 2023, at 7:28 AM, Christopher Warfel via RE-wrenches <
>> re-wrenches at lists.re-wrenches.org> wrote:
>>
>> 
>>
>> Seems confusing that the AHJ is requiring a disconnect for AC wiring, not
>> specific to which or both panel types, and then a dc disconnect with no
>> code reference.  Was trying to convey a reasonable, safe approach.  A lot
>> of bad information from fire department solar consultants making a lot of
>> money fear mongering, which has led to this type of situation.  Chris
>>
>> On 1/27/2023 3:35 PM, William Miller via RE-wrenches wrote:
>>
>> Glenn:
>>
>>
>>
>> As I wrote, a DC disconnect is required.  Here is an excerpt from the Q&A
>> with the building official:
>>
>>
>>
>> 4.   Will you be requiring an external disconnect to disconnect the AC
>> output of the inverter system from premise wiring?
>>
>> Yes, as required per 230.85
>>
>> 5.   Will you be requiring an external disconnect to disconnect
>> batteries from the inverters?
>>
>> Yes
>>
>>
>>
>> If the DC disconnect was not required I would not be wasting everyone’s
>> time with my post.  I try to be careful about that, researching on my own
>> before posting and trying to make my questions very clear.  I also try not
>> to embarrass myself with dumb questions, but that does happen occasionally…
>>
>>
>>
>> William
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Glenn Burt via RE-wrenches
>> *Sent:* Friday, January 27, 2023 11:46 AM
>> *To:* William Miller via RE-wrenches
>> *Cc:* Glenn Burt
>> *Subject:* Re: [RE-wrenches] Remote battery disconnects
>>
>>
>>
>> Does the AHJ really want the batteries disconnected from conductors, or
>> does he really just want the inverters to stop operating and producing AC
>> within the house?
>>
>> Obviously there is a big difference here and it may be changing as the
>> code evolves.
>>
>>
>>
>> -Glenn
>>
>> Sent from my 'smart'phone, so please excuse typos and spelling errors.
>>
>>
>>
>> ------ Original message------
>>
>> *From: *William Miller via RE-wrenches
>>
>> *Date: *Fri, Jan 27, 2023 2:26 PM
>>
>> *To: *RE-wrenches;
>>
>> *Cc: *William Miller;
>>
>> *Subject:*[RE-wrenches] Remote battery disconnects
>>
>>
>>
>> Friends:
>>
>>
>>
>> We have a large-ish residential off-grid system install coming up.  The
>> AHJ has said they will require a remote battery disconnect.  I suspect
>> there will be fire sprinkler controls and a pressure pump that would become
>> inoperable if this system were engaged.  In this case we will apply for a
>> waiver.
>>
>>
>>
>> The last time this was discussed here as far as I can find was October of
>> 2020.  At that time no one suggested any specific battery disconnect
>> equipment.
>>
>>
>>
>> To further clarify my needs:  There will be 4 or 5 Radian 8048 inverters
>> (5 or 6 4/0 battery circuits, ~350A each) and two 175 amp PV recombiner
>> outputs.  That is 6 poles of high amperage DC disconnects.
>>
>>
>>
>> The battery array will be either a UnigyII VRLA or a lithium of a brand
>> yet to be determined.  In the case of lithium we will look for a system
>> that can remotely enable a BMS shutdown.  In the case of a VRLA lead-acid,
>> we will not have that luxury.
>>
>>
>>
>> I have done some considerable research and have not found viable, high
>> amperage, remotely activated shutdown equipment.
>>
>>
>>
>> I am wondering what hardware others may be using to achieve remote
>> battery disconnecting in these types of cases..
>>
>>
>>
>> William
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
>>
>>
>>
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>> --

William Miller
Miller Solar.com
895-438-5600
www.millersolar.com
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