Rapid Shutdown for Ground mount with inverter in garage

[electrofelon]

What we need to do is have an electrician exchange program where we all work for each other and learn each other’s secrets. Now that would be helpful! I learn a lot from here.

My go to single phase package is Unirac GFT with SMA 7.7’s. The single biggest problem I have with those is wifi connectivity, so no more using wifi with them — they are terrible. Ethernet only to a switch with a wifi bridge, I include that in our bids now.

We actually typically don't provide any monitoring. We are quite a bit lower in cost then the competition, and that is one thing we skip, and actually we haven't yet had a client they really even cares about it. They can go look at the inverters to see their numbers. If you need data connectivity for a far away ground mount that has the inverters there, I would use internet over power, they work super great now.

 

[ggunn]

We actually typically don't provide any monitoring. We are quite a bit lower in cost then the competition, and that is one thing we skip, and actually we haven't yet had a client they really even cares about it. They can go look at the inverters to see their numbers. If you need data connectivity for a far away ground mount that has the inverters there, I would use internet over power, they work super great now.

Or shielded CAT(x).

 

[BackCountry]

We actually typically don't provide any monitoring. We are quite a bit lower in cost then the competition, and that is one thing we skip, and actually we haven't yet had a client they really even cares about it. They can go look at the inverters to see their numbers. If you need data connectivity for a far away ground mount that has the inverters there, I would use internet over power, they work super great now.

I’ve had a few SMA inverter failures that monitoring has caught. One was an insulation knick that eventually arc’d through the conductor and failed a string.

I think we are very monitoring forward because we use Enphase so much.

 

[electrofelon]

I’ve had a few SMA inverter failures that monitoring has caught. One was an insulation knick that eventually arc’d through the conductor and failed a string.

I think we are very monitoring forward because we use Enphase so much.

Yeah it's kinda weird to me. It's almost like the industry expects some fancy system monitor sitting on the dining room table or an app on your phone, and that people will need/want it. I haven't even add any clients that give a hoot. We just tell them to check the inverters periodically for an error code.

 

[BackCountry]

Yeah it's kinda weird to me. It's almost like the industry expects some fancy system monitor sitting on the dining room table or an app on your phone, and that people will need/want it. I haven't even add any clients that give a hoot. We just tell them to check the inverters periodically for an error code.

It’s for sure getting that way.

We had a customer that was bummed out because the SolarEdge backup interface takes about a second to kick over in a grid outage.

It sure would save a lot of time to not have to deal with it. On commercial we require Ethernet to be provided or LTE.

Looping back to rapid shutdown, I agree that the AC side being inside the building brings you back into rapid shutdown. If outside isn’t an option, you may be in a tough spot. Of course, it depends on what inverter you’re using.

 

[ggunn]

Looping back to rapid shutdown, I agree that the AC side being inside the building brings you back into rapid shutdown. If outside isn’t an option, you may be in a tough spot. Of course, it depends on what inverter you’re using.

What has rapid shutdown got to do with AC conductors? I don't know how the AC conductors from an inverter could continue to be energized during a power outage; UL1741 ensures that the inverter will shut down. Am I missing something?

 

[pv_n00b]

Well, OK, but don't they comply by default? Do AC inverter output conductors retain any DC voltage when power from the utility is interrupted? I would not think so.

RSD is not limited to DC voltage. There should never be DC voltage on the AC output. In the 2020 NEC RSD was revised to only apply to AC when it originates in the PV array. Prior to that, all PV AC was under RSD if the system required RSD.

 

[ggunn]

RSD is not limited to DC voltage. There should never be DC voltage on the AC output. In the 2020 NEC RSD was revised to only apply to AC when it originates in the PV array. Prior to that, all PV AC was under RSD if the system required RSD.

I still don't get it; see post #26. Are you talking about PV with ESS where the PV continues to run in an outage?

 

[jaggedben]

I never regarded AC conductors outside the array as being controlled. And now the 2020 NEC says they are not.

The only practical difference I see is, if your RS switch only deals with DC, that it has to be grouped with the service or feeder or other AC disconnect that shuts down the AC side. I've yet to see an AHJ go that nitty gritty.

Ggunn your comments about UL1741 don't really cover systems with backup capability. Or Enphase IQ8.

 

[BackCountry]

I never regarded AC conductors outside the array as being controlled. And now the 2020 NEC says they are not.

The only practical difference I see is, if your RS switch only deals with DC, that it has to be grouped with the service or feeder or other AC disconnect that shuts down the AC side. I've yet to see an AHJ go that nitty gritty.

Ggunn your comments about UL1741 don't really cover systems with backup capability. Or Enphase IQ8.

Exactly, there has to be a rapid shutdown initiator.

 

[ggunn]

Exactly, there has to be a rapid shutdown initiator.

I did not think that the ground mounted PV system that is the subject of this thread has ESS attached or Enphase inverters. Was I mistaken, or did the thread diverge?

 

[BackCountry]

I did not think that the ground mounted PV system that is the subject of this thread has ESS attached. Was I mistaken, or did the thread diverge?

Probably diverged — just making the point about Enphase.

 

[jaggedben]

I did not think that the ground mounted PV system that is the subject of this thread has ESS attached or Enphase inverters. Was I mistaken, or did the thread diverge?

OP: "a DC-coupled ESS for partial home backup will be in the basement."

 

[wwhitney]

Going back to the OP, I think it's clear now that under the 2017 NEC rapid shutdown is required as soon as the DC conductors reach the outside of the building?

In that 690.12(B)(1)'s "or" is inclusive, and the conductors are clearly outside the array boundary. So once the DC conductors reach the outside of the building, they fall under the scope of 690.12 ("PV system circuits installed on . . . buildings").

Cheers, Wayne

 

[ggunn]

OP: "a DC-coupled ESS for partial home backup will be in the basement."

OK; is it interconnected so that the PV system will continue to run during an outage?

 

[jaggedben]

OK; is it interconnected so that the PV system will continue to run during an outage?

That's what 'partial home backup' means to me.

 

[jaggedben]

Which means that neither the service disconnect nor the feeder disconnect at the garage can be the rapid shutdown initiation device in this installation.

 

[BackCountry]

Which means that neither the service disconnect nor the feeder disconnect at the garage can be the rapid shutdown initiation device in this installation.

Right, so an external rapid shutdown initiation switch is required. Seems like the design on this could be altered if equipment was all outside, but that’s coming from a Californian.

 

[ggunn]

That's what 'partial home backup' means to me.

Not necessarily. It means to me that in the event of an outage part of the home will have power and the rest will not, irrespective of whether the PV continues to run or not. With Powerwalls and microinverters it is fairly easy to keep the PV running so that with judicious load management and sunny days it can be possible to run indefinitely, but with string inverters and DC coupled backup, I don't know; I haven't dealt with that.

 

[jaggedben]

Not necessarily.

Oh come on. Yes necessarily, especially since it's a DC coupled ESS, meaning both the PV and ESS power the same inverter. Backup means that if power from the grid is lost then the system will keep running from whichever is available, that's the whole point.

Beyond that, he said it was Solaredge, and we know generally how that works. I just don't know what exact equipment he is using and how Solaredge supports an RS switch these days, I haven't kept up.

It means to me that in the event of an outage part of the home will have power and the rest will not, irrespective of whether the PV continues to run or not. With Powerwalls and microinverters it is fairly easy to keep the PV running so that with judicious load management and sunny days it can be possible to run indefinitely, but with string inverters and DC coupled backup, I don't know; I haven't dealt with that.

It's basically all the same. As you know, with Powerwalls and microinverters in backup setup, the service disconnect cannot be the rapid shutdown switch.