[RE-wrenches] Rapid Shutdown
Ray Walters
ray at solarray.com
Tue Mar 15 17:23:15 PDT 2016
Hi Brad;
I think that remotely tripping the inverter might work with Outback, but
definitely not with Magnum. (I checked with them today) Also, if the
battery cables are more than 5 ft long, the rapid disconnect /might/
have to be closer to the batteries. (/690.12 ...shall apply only to PV
system conductors more than 5 ft in length inside the building...)
/As for inverter and overall system reliability? I'm afraid that//is
going 'Rapidly' down hill.// Decades//of experience says that the more
gizmos and automatic controls you add, the more chances you have for
something to go wrong. The Birdhouse system defaults to/'off' /with any
communications problems, so one CAT 5 cable has a nick in it, and the
entire system crashes.//With all this emphasis on safety, we also need
to be thinking about our customers living alone in cold, remote locations./
/Perhaps an emergency disconnect for the emergency disconnect?
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 3/15/2016 5:45 PM, Bradley Bassett wrote:
> I've been promoting the use of the remote on/off terminals that are
> available in most inverters, which can be connected to the AUX in the
> Birdhouse. For a very minimum effort and cost, the inverter AC output
> would be shutdown when the rapid shutdown is activated. I think using
> the remote on/off terminals seems a lot cleaner way to do this than
> disconnecting the battery cables. And there is the possibility that
> disconnecting the battery from a fully loaded inverter may damage the
> inverter, do we really want to risk that whenever we test the RSD
> system? None of the current inverter mfg will say that this will do
> any damage, but they don't seem very convinced to me. I remember a
> decade ago when they did say there could be an issue. I'm not sure how
> much different inverters are now than then.
>
> Brad
> AEE Solar
>
> On Tue, Mar 15, 2016 at 12:48 PM, Patrick Shortell
> <pshortell6 at gmail.com <mailto:pshortell6 at gmail.com>> wrote:
>
> Dear List,
> Maybe it's an over simplistic opinion, but shouldnt all sources be
> disconnected rapidly in an emergency situation.
> We can always do better than what the code requires. I get
> frustrated when people go to the book, (and try to hide behind the
> text). instead of thinking through real life scenarios.
> There are simple ways to work around these issues.
> I find when something is questionable, Ill call the AHJ and get
> his approval First.
> What would I do in my own house?
> What if someone thought all the power was off when they dragged a
> hoseline into my basement.
> My two cents
> Pat
>
> On Tue, Mar 15, 2016 at 1:10 PM, <billbrooks7 at sbcglobal.net
> <mailto:billbrooks7 at sbcglobal.net>> wrote:
>
> Ray,
>
> I guess I have to step in after that acknowledgement. PV
> system circuit is a
> self-defined term and therefore cannot be defined unless you
> are going to
> develop a meaning that is different from the self-definition.
> It means ANY
> circuit in a PV system. This includes battery and stand-alone
> circuits in
> the 2014 NEC.
>
> The language of the 2014 NEC was a compromise between the fire
> service and
> the PV industry. Originally, the language required
> essentially module-level
> shutdown. I raised the concern with the PV industry to get
> them involved
> since most were not paying attention at the time. This
> language was
> developed and intended to cover all circuits in a PV system.
> In the 2014
> NEC, batteries are part of a PV system and therefore fall
> under this
> requirement.
>
> 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. Don't shoot the messenger on this one and don't
> think for a minute
> that I alone made this requirement or am alone in interpreting
> it in this
> way. I did author this compromise with other representatives
> of the PV
> industry so I think I know what the intent was.
>
> It is understandably difficult for battery systems and I would
> try to keep
> battery circuits as short as possible. The 5-feet was intended
> to match the
> requirement of 690.71(H)--which is further evidence of the
> intent of the
> 2014 NEC.
>
> The 2017 NEC removes batteries from the requirement, but they
> still cannot
> backfeed the PV array. Energy storage systems (Article 706)
> will have their
> own requirements in time--that is guaranteed.
>
> Bill.
>
>
> -----Original Message-----
> From: RE-wrenches
> [mailto:re-wrenches-bounces at lists.re-wrenches.org
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] On
> Behalf Of Ray Walters
> Sent: Tuesday, March 15, 2016 9:02 AM
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org
> <mailto:re-wrenches at lists.re-wrenches.org>>
> Subject: [RE-wrenches] Rapid Shutdown
>
> Greetings Esteemed Wrenches:
>
> I've just heard back from our inspector here in Colorado, and
> we are still
> being required to disconnect the batteries under 690.12. No
> where in 690.12
> are batteries mentioned, nor in the appropriate 690.71 section
> that deals
> with batteries. The entire reasoning behind this is based on
> a single
> article written by a single person: Bill Brooks. I have
> contacted both
> Outback and Magnum on this issue, and their engineers are
> unaware that rapid
> shutdown applies.
> My interpretation is that I could install an inverter and
> battery system
> that was charged from a generator, and we would not need any
> rapid shutdown
> at all. But according to Bill, as soon as I put a single
> solar module into
> the system, suddenly the entire system becomes PV? The problem
> lies with the
> term 'PV System circuit' used in 690.12. 690.2 Defines 'PV Output
> circuit', and 'PV source circuit', but there is no 'PV system
> circuit'
> defined. 690.12 therefore uses an undefined term.
> Our design uses 2 inverters, so if we used Midnite's E panel
> with their
> remote trip breakers, the 2nd inverter would be more than 5 ft
> from the
> batteries. If we used Magnum or Outback DC disconnects (that
> would comply
> with the 5 ft rule specified in 690.71) they don't offer
> remote trip.
> We have a Midnite Rapid disconnect Combiner on the roof with
> the Birdhouse,
> so we are complying with 690.12, it should not be applied to
> batteries
> though.
>
> Thanks,
>
> --
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760 <tel:303%20505-8760>
>
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> --
> Patrick A. Shortell
> /Licensed Master Electrician/
> /Certified Solar Installer/
> 71 Oregon Street
> Long Beach N.Y. 11561
> cell: 516-477-0221 <tel:516-477-0221>
>
>
>
>
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