[RE-wrenches] Rapid shutdown questions

Wed Aug 27 07:31:47 PDT 2014

Hey Mac,

1.  What is a (currently listed) rapid shutdown system that will
accommodate 8 strings?  I know I can do this with Midnite combiners but as
I understand these aren't listed yet.

Contacting combiners from several mfgs or Midnite combiners would work.
 Everything in PV systems pretty much has to be listed per 690.4(B), and
this listing requirement is repeated - perhaps excessively throughout 690.
 There is no single Standard to list rapid shutdown equipment to - the
intent of the listing requirement in 690.12(5) is more general, as in a
combiner box that is listed to 1741 and contains manufacturer assembled
components rated for the application (i.e. current and voltage).  The
combiner box could also be listed to 1699B for arc-fault protection.  But
it cannot be listed to XXXX for rapid shutdown because that listing doesn't
exist.

Note that depending on the type of inverter in the system, additional
isolating means at the charge controller and/or inverter may be required
due to internal capacitance on the dc input side of the equipment.  Talk to
the equipment mfgs to verify this.

2.  On a remote pole mount, does rapid shutdown apply?  If the intent is to
isolate a safe zone around an array for fire fighting, it seems as though a
standard pole mounted DC disconnect can cover this concern.

690.12 is for "Rapid Shutdown of PV Systems on Buildings".  Depending on
where the PV system circuits are routed (inv/cc/batteries inside?) they may
be subject to these requirements, but a grid-direct system, with the
inverter at the pole, would meet shutdown requirements through it's ac
disconnect/backfed breaker at the service.

3.  I estimate on a typical hybrid installation, rapid shutdown will cost
at least $3000 to implement. This includes remote shunt trip battery
breakers, contactors on PV side of charge controller and roof combiners,
and running control cable from remote disconnect to all locations.  As of
now, this would also require me to modify listed interconnection equipment.
 Is this what others are finding?

690.71(H) already requires a disconnect at batteries if the cables are more
than 5 feet long, at which length rapid shutdown would be required as well.
 So if it's any consolation you killing 2 birds with 1 remotely
activate-able switch!  Plus roof-mounted combiners need a disconnect within
6 feet (690.15(C)), so that's another two-fer too.

How do you mean "modify listed interconnection equipment"?

4.  AC coupling with microinverters may be the easiest way to comply with
most of these requirements.  However, this doesn't seem like a great
alternative to the standard charge controller installation in an off-grid
system.

Thanks in advance for your thoughts

Brian Mehalic
NABCEP Certified Solar PV Installation Professional™ R031508-59

PV Curriculum Developer and Instructor
Solar Energy International
http://www.solarenergy.org

On Wed, Aug 27, 2014 at 10:01 AM, Mac Lewis <maclewis1 at gmail.com> wrote:

> Hi Will,
>
> Yes I'm sure AHJ's will be all over the place for a while here in
> Colorado.  To clarify, is this a manual disconnect in the attic?  If so,
> that is really missing the whole idea of a rapid shutdown.
>
> Thanks
>
>
> On Wed, Aug 27, 2014 at 7:47 AM, Will White <William.White at rgsenergy.com>
> wrote:
>
>>  Our experience in MA with rapid shutdown unfortunately varies with
>> AHJ.  Some are letting us put an Eaton NEMA 4 disconnect on the roof next
>> to the array.  Some are letting us put a disconnect in an accessible attic
>> within 5’ of the penetration.  Some are requiring the Midnight Birdhouse
>> remote switch which is expensive.
>>
>>
>>
>> Rapid shutdown doesn’t apply to pole or ground mounts.
>>
>>
>>
>> Hope this helps.
>>
>>
>>
>> Will
>>
>>
>>
>> *Will White*
>> Operations Manager - New England
>>
>> RGS Energy
>>
>> 64 Main St. |Montpelier, VT 05602
>> tel 802.223.7804 | mobile 802.234.3167 | fax 802.223.8980
>>
>> *RGSEnergy.com <http://www.rgsenergy.com/> **|
>> william.white at rgsenergy.com <william.white at rgsenergy.com> *
>>
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>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
>> Behalf Of *Mac Lewis
>> *Sent:* Wednesday, August 27, 2014 8:32 AM
>> *To:* RE-wrenches
>> *Subject:* [RE-wrenches] Rapid shutdown questions
>>
>>
>>
>> Hello wrenches,
>>
>>
>>
>> I am still trying to wrap my head around how to comply with rapid
>> shutdown in off-grid and hybrid situations.  I've got a few questions that
>> maybe you can help with.
>>
>>
>>
>> 1.  What is a (currently listed) rapid shutdown system that will
>> accommodate 8 strings?  I know I can do this with Midnite combiners but as
>> I understand these aren't listed yet.
>>
>> 2.  On a remote pole mount, does rapid shutdown apply?  If the intent is
>> to isolate a safe zone around an array for fire fighting, it seems as
>> though a standard pole mounted DC disconnect can cover this concern.
>>
>> 3.  I estimate on a typical hybrid installation, rapid shutdown will cost
>> at least $3000 to implement. This includes remote shunt trip battery
>> breakers, contactors on PV side of charge controller and roof combiners,
>> and running control cable from remote disconnect to all locations.  As of
>> now, this would also require me to modify listed interconnection equipment.
>>  Is this what others are finding?
>>
>> 4.  AC coupling with microinverters may be the easiest way to comply with
>> most of these requirements.  However, this doesn't seem like a great
>> alternative to the standard charge controller installation in an off-grid
>> system.
>>
>>
>>
>> Thanks in advance for your thoughts
>>
>>
>>
>>
>>
>> --
>>
>>
>>
>>
>>
>>
>>
>> Mac Lewis
>>
>> "Yo solo sé que no sé nada." *-Sócrates*
>>
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>
>
> --
>
>
>
> Mac Lewis
>
> * "Yo solo sé que no sé nada." -Sócrates *
>
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