[RE-wrenches] Rapid Shutdown

Ray Walters ray at solarray.com
Tue Mar 15 21:04:27 PDT 2016


We were discussing remotely turning on and off the inverter itself like 
with the Outback's remote on/ off terminals.  Magnum only has their 
remotes which aren't compatible with other systems.

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 3/15/2016 8:04 PM, bob at midnitesolar.com wrote:
>
>
> On 3/15/2016 5:23 PM, Ray Walters wrote:
>> 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...)
>> /
> *
>
> Ray,
>
> There is no reason at all that any battery based inverter should not 
> work with our RSS system.
>
> Did they give you a reason why the inverter can't be turned off by 
> switching off its battery circuit breaker ?
>
> I almost always turn off a Magnum inverter (or other inverter) by 
> switching off its battery breaker,
> at least when we're testing an E-panel system.  Works every time 
> except maybe if the grid
> is or generator is connected and running.  In a shutdown condition, 
> those two things would
> be dead and inactive.
>
> Also, Our 600V Cat5 cable is USE-2 rated, shielded and tougher than nails.
>
> Thanks and hallucinations,
> boB
> *
>
>> /
>> /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> 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> 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] On
>>>         Behalf Of Ray Walters
>>>         Sent: Tuesday, March 15, 2016 9:02 AM
>>>         To: RE-wrenches <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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