2014 NEC 690.12 Emergency Shutdown

[SolarPro]

"Ok how about some Listed and Identified products to install for this 690.12 Rapid Shutdown function?"

Okay, here are several ways to meet the requirement:

1. Locate string inverters within 10' of the array.

2. Install contactor combiner boxes on the roof w/ an on/off button on the ground.

3. Use module-level products, either dc-to-dc converters, microinverters or ACPV modules.

While the equipment used needs to be listed, it generally doesn't need to be listed to some new product standard that doesn't exist yet. These requirements can be met with off-the-shelf components and technologies.

 

[MWh_Pro]

SolarPro-- thank you for your explanation of 690.12, it was incredibly helpful. As far as what's the best method for implementing the "Rapid Shutdown" feature, in order of desirability, I would suggest the following:

1. String inverters within 10' of the array. Operating the main (ground level) AC disconnect could then be marked as required by 690.56(B): "MAXIMUM VOLTAGE AT ARRAY 80VDC AFTER SHUTDOWN". Presuming actuating the main AC disconnect turns off the inverters within 10 seconds, you would have fulfilled 690.12. I assume that you would verify this during system inspection and commissioning. This method is quite clever since it doesn't require additional equipment.

2. Contactor combiners within 10' of the array, for those who elect to use a central inverter.

3. Module level electronics: Tigo boxes, Enphase, etc. are very nice, it just takes a bit of time to get comfortable with the technology and there is a bigger investment up-front and during installation. In my experience, NOT desirable for installations larger than 100kW.

4. DC disconnect within 10' of the array. I agree with you, SolarPro, in that this defeats the intent of 690.12. In most cases the disconnect would not be readily accessible, and if you have more than one DC disconnect it certainly would not create a central "OFF" button for the PV array. I do believe putting the disconnect as close to the array is a good idea, since it creates a way to separate PV output circuit conductors from the array.

Let me know what you think-- I'm just getting up to speed on this piece of code and would greatly appreciate your input!

 

[Ryan.Midnite]

4. DC disconnect within 10' of the array. I agree with you, SolarPro, in that this defeats the intent of 690.12. In most cases the disconnect would not be readily accessible, and if you have more than one DC disconnect it certainly would not create a central "OFF" button for the PV array. I do believe putting the disconnect as close to the array is a good idea, since it creates a way to separate PV output circuit conductors from the array.

As a manufacturer of Renewable Energy balance of system gear we offer a Combiner box that can be remotely tripped by a single push button. We have a pretty wide variety of items to help be compliant with 690.12 even on the battery side. I am not adding any links or stuff as I am not sure of the forum rules on that type of thing.

As a licensed Electrician I am horified at how 690.12 got written into the NEC the intent of the rule was simple. A readily accessible single push button that turns off all PV within so many feet of the PV array and ALL battery based gear at the gear. The way it got written basically says the "Rapid System shutdown device" could be locked in an attic. This is going to lead to inspectors interpreting this different all over the place.

Ryan

 

[ColRob2726]

Multiple Sub-Arrays and Enclosure Ratings

Multiple Sub-Arrays and Enclosure Ratings

All,
The main difficulty I have is that many Residential Systems are comprised of several sub-arrays. Installing an inverter within 10' (extremely rare site compatibility) of one sub-array means the other would be out of compliance. Combiners aren't desirable in these situations either as some sub-arrays are only partial strings (say 8 of 12). Then, there's the issue of enclosure ratings. Please correct me if I'm wrong, but, NEMA 4 rated enclosures would be the cheapest option to avoid mounting the enclosure vertically. That's leading to runaway cost increases. What solutions are you aware of that do NOT combine the strings and avoid enclosure mounting problems? Is this just a minimum $1800 tax on string inverters?

Since "remote activation" or "single point of control" are not literally mentioned in the code, I'd like to ignore those features to get a base level solution for multi-array systems.

Thank you,
Colin

 

[DougAles]

Could a moderator please give me a call? I'd like to add to this discussion, but do not wan't to be considered 'spamming' the board. My direct line +1.920.841.0935. Thanks!

 

[BillK-AZ]

All,
The main difficulty I have is that many Residential Systems are comprised of several sub-arrays. Installing an inverter within 10' (extremely rare site compatibility) of one sub-array means the other would be out of compliance. Combiners aren't desirable in these situations either as some sub-arrays are only partial strings (say 8 of 12). Then, there's the issue of enclosure ratings. Please correct me if I'm wrong, but, NEMA 4 rated enclosures would be the cheapest option to avoid mounting the enclosure vertically. That's leading to runaway cost increases. What solutions are you aware of that do NOT combine the strings and avoid enclosure mounting problems? Is this just a minimum $1800 tax on string inverters?

Since "remote activation" or "single point of control" are not literally mentioned in the code, I'd like to ignore those features to get a base level solution for multi-array systems.

Thank you,
Colin

Most inverters require an air flow for cooling and have angle of mounting requirements. NEMA-4 enclosures are sealed and any venting will void the listing.

 

[Zee]

All,
The main difficulty I have is that many Residential Systems are comprised of several sub-arrays. Installing an inverter within 10' (extremely rare site compatibility) of one sub-array means the other would be out of compliance. Combiners aren't desirable in these situations either as some sub-arrays are only partial strings (say 8 of 12). Then, there's the issue of enclosure ratings. Please correct me if I'm wrong, but, NEMA 4 rated enclosures would be the cheapest option to avoid mounting the enclosure vertically. That's leading to runaway cost increases. What solutions are you aware of that do NOT combine the strings and avoid enclosure mounting problems? Is this just a minimum $1800 tax on string inverters?

Since "remote activation" or "single point of control" are not literally mentioned in the code, I'd like to ignore those features to get a base level solution for multi-array systems.

Thank you,
Colin

Good points.
Answers:
1. Re. J-boxes: Soladeck. Flashing and JB all in one. "flashes" right into coursework of shingles on resi. roofs. Not NEMA 4, but built for sloped roofs, will never leak. Can be pre configured as JB, CB, you name it. I have become big fan. You can hide it under panels too!

2. Re. Sub arrays, partial strings, rapid shutdown issues: SolarEdge. Less cost than micros. ( I just installed 16 panels in two subarrays but it was all one string. No problem. Split orientations too, One sub-array faced S, the other W.)

 

[Carultch]

Please correct me if I'm wrong, but, NEMA 4 rated enclosures would be the cheapest option to avoid mounting the enclosure vertically.

NEMA3R doesn't necessarily mean that you need a vertical mounting. NEMA3R means that you need to mount it in the orientation specified by the manufacturer, in order for it to properly shed rain water. Most of the time this is vertical

The Soladeck enclosures are mounted flat, and they are NEMA3R.
Some inverter manufacturers now allow you to lay the inverter partially on its back, sometimes as flat as 15 degrees. While it will remain waterproof in this orientation, it may not maintain inverter performance, due to the hindered air cooling.

NEMA4 means that you can mount the enclosure in any orientation and it will be waterproof.

 

[Carultch]

Good points.
1. Re. J-boxes: Soladeck. Flashing and JB all in one. "flashes" right into coursework of shingles on resi. roofs. Not NEMA 4, but built for sloped roofs, will never leak. Can be pre configured as JB, CB, you name it. I have become big fan. You can hide it under panels too!

See 690.16. You do need to have the ability to service fuses, and using the Soladeck as a fused combiner makes this very difficult.

The Soladeck enclosures are good for pull boxes, transition boxes, and 2-to-1 fuseless combiner boxes, but not so much for combining 3 or more strings.