Hi Ray, The stand-alone diagram calls out the PV system disconnect right after the PV system DC circuits and prior to the point of common coupling with the batteries and the stand-alone inverter. Yes, you are correct a controller or DC to DC converter is not shown in the this diagram or the dc-coupled diagram.
The reason the charge controller is not called out in the diagram is because it can be on either side of the PV system disconnect, depending on the topology of the system. For example, a controller connected to a DC bus with multiple power sources that would still be operational if the PV system is disconnected would be outside the PV system disconnect demarcation. If the controller serves no purpose when the PV system is disconnected, then it makes sense to have the charge controller output circuit be the location of the PV system disconnect. One way to think about this is what happens when you open (turn off) the PV system disconnect. So for example a multimode inverter doesn't care if the PV system disco is open, it will just keep on doing its job, pulling power from the batteries and providing power to the loads. If the charge controller can't keep doing its job with no PV power source, then it really belongs to the PV system. Maybe this seems silly, but as particularly energy storage systems and microgrids get more complicated, it doesn't always make sense to have hard and fast rules about what equipment belongs to which system. I realize this makes rapid shutdown more confusing. But for a DC-coupled stand-alone system it seems the major question here is whether the RS shutdown switch (or switches) control the circuits before or after the charge controller. For most typical small systems, I would say probably after the controller, but I think this is open to some debate. The rules for locating a DC PV system disconnect are found in 690.13 - it really just has to be readily accessible. It may or may not also serve the purpose of the rapid shutdown initiation switch, that's up to you as the system designer. Best, Rebekah On Wed, Apr 18, 2018 at 12:56 AM, Ray <[email protected]> wrote: > Hi Rebekah; > > Thanks for pointing out the changes to the diagrams. I especially > appreciate Note (2). *The PV system disconnect in these diagrams > separates the PV system from all other systems.* > That seems simple enough for defining the boundaries of RSS, until you > think about off grid, and look at the last diagram of 690.1(b) titled > "Stand Alone System". The charge controller is not shown at all. Then > Figure 690.1(a) shows a *DC to DC Converter (optional location)*, shows a > fuse after, shows the power going with an arrow to no where, on a line > labeled *PV or DC to DC converter output circuit.....* But finally, the > cause of my greatest confusion: it does not show the *PV System > Disconnect* anywhere. > > I have several questions: > Is a charge controller a *DC to DC converter*? What about non MPPT > controllers that don't convert voltage? > Is a charge controller considered *DC* *utilization Equipment* mentioned > in the definition of *PV Output Circuit*, or is the inverter and DC loads > the utilization equipment? > All of which leads to the $20 thousand dollar question: Is the *PV System > Disconnect* before or after the charge controller? > If before the charge controller, where can the PV Disconnect be? Could it > be outside, at the pole, or does it need to be within 3 ft of the building > entry? > > Even with all the changes made in 2017, it seems that we still are left > with too much uncertainty about where a PV circuit ends, or what > constitutes the "PV Disconnect" in an off grid system. Not such a big > deal, until we are required to apply 690.12. > > Thanks everyone for your answers and opinions, > > Ray Walters > Design Engineer > Remote Solar > > > On 4/17/18 7:15 AM, Rebekah Hren wrote: > > Hi everyone, > > I strongly recommend looking at the figures that were added in NEC 2017 at > the beginning of Article 690 in 690.1(b). > > What they show is equipment that is part of the PV system (to the left of > the PV system disconnect called out in the diagrams), and equipment that is > not part of the PV system (to the right of the PV system disconnect). These > are really helpful diagrams, in terms of figuring out where the > requirements of Article 690 apply. > > Equipment *not* part of the PV system is not a "PV system circuit" and > thus is *not* subject to rapid shutdown requirements per 690.12. > > In every type of system you will see that energy storage is *not *part of > the PV system, and neither is the multimode inverter for a system with > energy storage. So rapid shutdown requirements shouldn't affect any of the > loads, multimode inverter, or batteries in an off-grid system. > > In the 2017 NEC, the PV system disconnect, as shown on the diagrams, is > required to be readily accessible per 690.13(A). For a system without > batteries, the PV system disconnect is *always *an AC disconnect, not a > DC disconnect. It can be the backfed breaker per 690.13(F)(1). For a > system with batteries the PV system disconnect is always before the > batteries. > > > Equipment disconnects, like the DC inverter disconnect, are not required > to be readily accessible, but must be within 10 feet of the equipment, per > 690.15(A). > > Also note that the boundary for rapid shutdown shrank to *one foot* from > the perimeter of the array in the 2017 NEC, so the inverter must be > positioned within one foot of the array if there is not going to be any > other RS equipment. The PV system disconnect (backfed breaker) or the > service disconnect can serve as the rapid shutdown initiation device in > that case. > > Best, > Rebekah Hren, Member of NEC CMP-4 for Solar Energy International > > -- > Tel: 336.266.8800 > NABCEP Certified Solar PV Installation Professional™ 091209-85 > NC Licensed Electrical Contractor > > > On Mon, Apr 16, 2018 at 9:00 PM, Ray <[email protected]> wrote: > >> For GT using Solar edge or Enphase, its not so hard to comply, but If you >> are looking at off grid systems, it's not just someone's opinion, its >> $1,000s of dollars extra to comply with 690.12. It also results in a system >> that is less reliable, which is less safe off grid where lives depend on >> that power for heat, light, refrigeration, and even breathing machines. >> >> Ray Walters >> >> Remote Solar >> >> On 4/16/18 7:44 AM, Brian Mehalic wrote: >> >> Hey y'all, I'm going to disagree about the NEC getting "worse and worse >> when it comes to PV," (see disconnect and grounding requirements, for >> instance!), but as with previous posters, that's just an opinion. >> >> Regarding location - the 2014 version had very little to say about the >> location of any rapid shutdown initiation device; 2017 adds the requirement >> [690.12(C)] that RS initiation devices for one- and two-family dwellings be >> readily accessible (defined in Article 100), AND outside the building. >> Seems reasonable for a device that is intended to control energized >> conductors to make it more safe to enter a building. >> >> Cheers, >> >> >> Brian Mehalic >> NABCEP Certified Solar PV Installation Professional™ R031508-59 >> 520.204.6639 >> >> Solar Energy International >> http://www.solarenergy.org >> >> SEI Professional Services >> http://www.seisolarpros.com >> >> >> On Mon, Apr 16, 2018 at 12:04 AM, Mark Frye <[email protected]> >> wrote: >> >>> Thanks Darryl. >>> >>> I guess I can add that I am in CA and so looked only at the 2014. I also >>> looked at the 2017 article. Man, I have to say, my impression remains that >>> really starting with 2008 the code has just gotten worse and worse when it >>> comes to PV, but that is just me. >>> >>> Not really sure what might need to be "Outside readily accessible". Is >>> there something other than 690.12 that I need to look at? >>> >>> Mark >>> On 4/15/2018 8:26 PM, Darryl Thayer wrote: >>> >>> I think the code says Outside readily accessible, >>> >>> On Sun, Apr 15, 2018 at 12:22 PM, Mark Frye <[email protected]> >>> wrote: >>> >>>> Folks, >>>> >>>> As I recall, an inverter and it's integrated DC disconnect need only be >>>> placed in an accessible location. I am thinking of putting an inverter high >>>> up on the wall inside a garage. That would be OK vis-a-vis the location of >>>> the disconnect (still accessible for maintenance). >>>> >>>> If I do put the inverter high up on the wall, I can limit my DC >>>> conductors to less that 10 feet total from the array and less that 5 feet >>>> inside the garage. >>>> >>>> That means I get the exemption from the rapid disconnect requirement, >>>> right? >>>> >>>> There is nothing in the Code linking the accessibility of the DC >>>> disconnect to the exemption from rapid shutdown, right? >>>> >>>> Mark Frye >>>> >>>> >>>> _______________________________________________ >>>> List sponsored by Redwood Alliance >>>> >>>> List Address: [email protected] >>>> >>>> Change listserver email address & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> >>>> List-Archive: http://www.mail-archive.com/re >>>> [email protected]/maillist.html >>>> >>>> List rules & etiquette: >>>> www.re-wrenches.org/etiquette.htm >>>> >>>> Check out or update participant bios: >>>> www.members.re-wrenches.org >>>> >>>> >>> >>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> List Address: [email protected] >>> >>> Change listserver email address & >>> settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> List-Archive: >>> http://www.mail-archive.com/[email protected]/maillist.html >>> >>> List rules & etiquette:www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios:www.members.re-wrenches.org >>> >>> >>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> List Address: [email protected] >>> >>> Change listserver email address & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> List-Archive: http://www.mail-archive.com/re >>> [email protected]/maillist.html >>> >>> List rules & etiquette: >>> www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> www.members.re-wrenches.org >>> >>> >>> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & >> settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/[email protected]/maillist.html >> >> List rules & etiquette:www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios:www.members.re-wrenches.org >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: http://www.mail-archive.com/re >> [email protected]/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> >> >> > > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & > settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/[email protected]/maillist.html > > List rules & etiquette:www.re-wrenches.org/etiquette.htm > > Check out or update participant bios:www.members.re-wrenches.org > > > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: http://www.mail-archive.com/[email protected]. > org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > > > -- Tel: 336.266.8800 NABCEP Certified Solar PV Installation Professional™ 091209-85 NC Licensed Electrical Contractor
_______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
