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Failed solar/powerwall inspection

Zinc_Saucier

Member
Jul 30, 2020
56
31
Massachusetts
If someone has 3x Powerwalls and AC coupled solar connected to the built-in panelboard on the Gateway 2, that means there's really no place to put an external throw switch. How in the world are people supposed to even set this up?

I’m in MA not CA, but my local solar installer is planning on installing the Gateway externally for PWs located in the basement to satisfy requirements to be able to turn off the solar and batteries. I was given the option to have a combo meter/breaker installed outside instead (at an additional cost of course) if I wanted the Gateway inside with the PWs.
 

adspguy

Member
Dec 1, 2016
204
189
Bedford MA
Also in MA and Eversource our utility required an external switch for the powerwalls and solar. In the picture the left meter is the grid and the right meter is a separate solar generation meter. The inverter and powerwalls (and their breakers) are in the basement. The inverter output goes through the meter and back inside to its breaker where it is combined with the powerwall’s breaker. Then the output from those breakers comes back out to the big switch which then goes to the gateway. Much more complicated to comply with the utility’s requirement for two outdoor meters and cutoff.
345CA076-6D07-4C59-A110-4B4B9E559944.jpeg

This was all included in the original “large system” 12.24kW price.
 
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holeydonut

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Jun 27, 2020
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East Bay NorCal
Also in MA and Eversource our utility required an external switch for the powerwalls and solar. In the picture the left meter is the grid and the right meter is a separate solar generation meter. The inverter and powerwalls (and their breakers) are in the basement. The inverter output goes through the meter and back inside to its breaker where it is combined with the powerwall’s breaker. Then the output from those breakers comes back out to the big switch which then goes to the gateway. Much more complicated to comply with the utility’s requirement for two outdoor meters and cutoff. View attachment 612317
This was all included in the original “large system” 12.24kW price.


Hmmm so you basically have a generation panel in you basement that feeds into the gateway 2. It sounds like you aren’t using the integrated panel on the gateway 2.
 

miimura

Well-Known Member
Aug 21, 2013
6,492
6,251
Los Altos, CA
Hmmm so you basically have a generation panel in you basement that feeds into the gateway 2. It sounds like you aren’t using the integrated panel on the gateway 2.
In California, if you install the Gateway 2 outside, the breakers in the internal panelboard can be the shutoff. I have micro-inverters and two Powerwalls and my equipment is all outdoors. There are no disconnect boxes in my installation. The breakers are the shutoffs and are labeled as such.
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
In California, if you install the Gateway 2 outside, the breakers in the internal panelboard can be the shutoff. I have micro-inverters and two Powerwalls and my equipment is all outdoors. There are no disconnect boxes in my installation. The breakers are the shutoffs and are labeled as such.

That makes sense... if the Gateway is outdoors they can just open it up and flip off the Eaton breakers.

But for some reason I feel like PG&E or the constantly evolving fire rules are going to crap all over me if I tried this now. My gut is telling me smart-a$$ PG&E troubleman (do they fix trouble or cause trouble?) is going to say how it's too hard to flip off Eaton breakers while wearing gloves. Or some bored inspector is going to say it's hard to see the Eaton breakers since they're so teeny tiny.

I'm going to see if Sunrun can turn my Enphase 3C-ES box into a Generation panel that the 3x Powerwalls plug into as well. So I'll have 35A for solar, plus 30A x 3 for each Powerwall feeding this Enphase box (125 A max rating).

Then I can run this (outside of my house) to an Eaton CD224NRB which will have one of those big-a$$ levers.

Then run this cool outdoor switch thing to the TEG 2 (through a 125 A breaker on the internal panelboard).

This way I can't get dinged for:
1) people with glove-hands
2) failing to have a single OCPD for the self-generation equipment

Then I can pay @Vines to use his fancy CNC machine to make one of the most fancy warning plaques in the world. With 3M reflective tape lettering.
 
Last edited:

holeydonut

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Jun 27, 2020
2,114
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East Bay NorCal
Damn it, the Enphase combiner can’t support more than 80A and can’t be commingled with Powerwalls.

I wonder if it’s possible to splice in that big lever switch between the energy gateway’s internal panelboard and the bottom lugs on the gateway.
 

charlesj

Active Member
Oct 22, 2019
1,239
272
Monterey, CA
In California, if you install the Gateway 2 outside, the breakers in the internal panelboard can be the shutoff. I have micro-inverters and two Powerwalls and my equipment is all outdoors. There are no disconnect boxes in my installation. The breakers are the shutoffs and are labeled as such.
Yep, just like mine.
 

holeydonut

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Jun 27, 2020
2,114
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East Bay NorCal
SON OF A, I just looked at my Sunrun line diagram and they have it going like this.


Main Service Panel rated at 200 A (solar ready Square D SC2040M200PF with 225 A bus bar)
Main Service Panel Houses a 200 A main breaker
Feeds into a 200 AC Disconnect (the box with the big lever)
Feeds Tesla Energy Gateway 2


Yes, they put the AC Disconnect outside of the Gateway which means the switch does nothing that the main 200A breaker wasn't already doing.

upload_2020-11-27_21-36-28.png
 

Vines

Active Member
Jul 20, 2018
2,050
2,379
Silicon Valley, CA
As far as code goes there is no reason in most cities that Powerwalls must have a means of disconnect on the external structure. I cannot speak as to Rocklin rules, but it is good practice to be able to shut down power to the facility from the outside.

Rooftop PV however may remain energized by the addition of Powerwalls, so they still must be able to be rapid shutdown, there are multiple code compliant ways to do this.
 

holeydonut

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Jun 27, 2020
2,114
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East Bay NorCal
Cross-posting this from my other thread...

According to PG&E, molded case circuit breakers are not allowed for the disconnect between the Grid and the distributed energy generation system (which I think includes both solar and ESS). So for the grid disconnect, you need that big box like what @adspguy posted.

https://www.pge.com/includes/docs/p...lity/electrictransmission/handbook/060559.pdf
#11: Molded case circuit breakers, pull-out type disconnects, or any other similar device are not acceptable as an approved disconnect switch.

That means Sunrun did put the bladed AC disconnect in the right location; since they wanted the bladed disconnect to work with PG&E's requirement. But their disconnect wouldn't work for a fire-safety requirement since the house itself would still be energized and potentially unsafe for emergency workers in my home.

As @Vines pointed out, if you use the same disconnect to keep both PG&E safe and firemen safe... then PG&E would disable your home backup solution if they ever had to work on services near your home. I guess the "safest possible answer" is to provide firemen access to shut off your PV and batteries that is a separate item than the big lever box that PG&E requires.

I'm trying to see if fire-safety requirements also deny the use of molded case breakers...

Seems like overkill to do this, but then the inspectors can't poo poo on anything.
 
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h2ofun

Active Member
Aug 11, 2020
2,936
564
auburn, ca
SON OF A, I just looked at my Sunrun line diagram and they have it going like this.


Main Service Panel rated at 200 A (solar ready Square D SC2040M200PF with 225 A bus bar)
Main Service Panel Houses a 200 A main breaker
Feeds into a 200 AC Disconnect (the box with the big lever)
Feeds Tesla Energy Gateway 2


Yes, they put the AC Disconnect outside of the Gateway which means the switch does nothing that the main 200A breaker wasn't already doing.

View attachment 612491

If one is wearing gloves, seems the switch is easy to engage, while the breakers take some extra effort
 

holeydonut

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Jun 27, 2020
2,114
1,500
East Bay NorCal
If one is wearing gloves, seems the switch is easy to engage, while the breakers take some extra effort


Yeah, I agree the big lever option makes sense because the teeny tiny BR style breakers are hard to operate with gloves. Now that I've seen PG&E's requirement, I understand why Sunrun wanted to put their bladed disconnect outside of my gateway. They wanted it so that if PG&E ever had to work on my house, I'd still have electricity.

But where Sunrun put the bladed disconnect, it wouldn't de-energize my home for fire safety. My understanding is that firemen need to be able to access the roof without the solar being active. And they need to be able to take an axe to the wall without hitting live wires.

There doesn't seem to be a perfect world where the same disconnect could be used for both PG&E and fire safety. So I need to use what Sunrun drew up for PG&E, but I would still want to add a new disconnect somewhere within the Gateway for the firemen. I would assume the firemen would want a gigantic lever as well, but I can't find language that says firemen safety denies the use of a molded case breaker as the disconnect.
 

h2ofun

Active Member
Aug 11, 2020
2,936
564
auburn, ca
Yeah, I agree the big lever option makes sense because the teeny tiny BR style breakers are hard to operate with gloves. Now that I've seen PG&E's requirement, I understand why Sunrun wanted to put their bladed disconnect outside of my gateway. They wanted it so that if PG&E ever had to work on my house, I'd still have electricity.

But where Sunrun put the bladed disconnect, it wouldn't de-energize my home for fire safety. My understanding is that firemen need to be able to access the roof without the solar being active. And they need to be able to take an axe to the wall without hitting live wires.

There doesn't seem to be a perfect world where the same disconnect could be used for both PG&E and fire safety. So I need to use what Sunrun drew up for PG&E, but I would still want to add a new disconnect somewhere within the Gateway for the firemen. I would assume the firemen would want a gigantic lever as well, but I can't find language that says firemen safety denies the use of a molded case breaker as the disconnect.

Have you called your fire department to ask them if there is any requirement that you imply is not in the code?
 

holeydonut

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Jun 27, 2020
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1,500
East Bay NorCal
Have you called your fire department to ask them if there is any requirement that you imply is not in the code?

Yes, but they said the person inspecting wouldn't be coming out of the fire department, so that's still kind of a shot in the dark. Local fire safety AHJs can always add requirements on top of the federal language; the guy just didn't know who to put me in contact with lol.

In 2017 NEC 705.23, there is some language around requirements for "Interactive energy systems" (power systems, energy storage, and associated premises wiring). I think based on this a UL98 breaker on the DC side is ok; and a UL489 (molded case) is ok on the AC side of these systems.

Since Enphase microinverters have built-in DC rapid shutdown, I guess a UL489 for both PV and ESS is ok for the fire safety rapid shutdown. But PG&E wants that big beefy lever ... because PG&E gonna PG&E.
 

SMAlset

Well-Known Member
Mar 4, 2017
9,185
9,913
SF Bay Area
Also in MA and Eversource our utility required an external switch for the powerwalls and solar. In the picture the left meter is the grid and the right meter is a separate solar generation meter. The inverter and powerwalls (and their breakers) are in the basement. The inverter output goes through the meter and back inside to its breaker where it is combined with the powerwall’s breaker. Then the output from those breakers comes back out to the big switch which then goes to the gateway. Much more complicated to comply with the utility’s requirement for two outdoor meters and cutoff. View attachment 612317
This was all included in the original “large system” 12.24kW price.

That’s one honking large AC Disconnect box there (comparing it to the TG2 next to it). Here’s ours; PG&E area. I’d have to go out and measure it but positive it’s way smaller.

E11470B0-BCB7-421D-8A33-701A1FFFEE35.jpeg
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
That’s one honking large AC Disconnect box there (comparing it to the TG2 next to it). Here’s ours; PG&E area. I’d have to go out and measure it but positive it’s way smaller.

View attachment 613159

Yeah, it looks like they put the 60A Eaton disconnect on your home while adspguy has the 200A model. I have no clue how your install is running 8 kWp of solar plus 3 PW's through a 60 A disconnect. Maybe that box you have only shuts down the solar? If so, that setup wouldn't work for PG&E's requirement to prevent all energy generation systems and storage from touching the grid.

The way adspguy's is wired would satisfy both the utility's need for a safety disconnect as well as the fire-safety need for a rapid shutdown. But if the local utility ever had to do work on adspguy's home and flipped that switch, he'd lose power at his house since his backup would be disabled too.
 

holeydonut

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Jun 27, 2020
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East Bay NorCal
Looks like a Tesla Tech will be out here tomorrow to install the exterior disconnect. @holeydonut I'll take some pics for you on what they did.


Awesome, thanks for that! Hopefully the Tesla Tech will be able to explain what happens in the two emergency scenarios...

1) When PG&E needs to disconnect your system from the grid to safely work on their equipment
2) When a fireman needs to rapidly shut down your system to safely get on the roof and poke holes in your walls
 

Vines

Active Member
Jul 20, 2018
2,050
2,379
Silicon Valley, CA
Cross-posting this from my other thread...

According to PG&E, molded case circuit breakers are not allowed for the disconnect between the Grid and the distributed energy generation system (which I think includes both solar and ESS). So for the grid disconnect, you need that big box like what @adspguy posted.

https://www.pge.com/includes/docs/p...lity/electrictransmission/handbook/060559.pdf
#11: Molded case circuit breakers, pull-out type disconnects, or any other similar device are not acceptable as an approved disconnect switch.

That means Sunrun did put the bladed AC disconnect in the right location; since they wanted the bladed disconnect to work with PG&E's requirement. But their disconnect wouldn't work for a fire-safety requirement since the house itself would still be energized and potentially unsafe for emergency workers in my home.

As @Vines pointed out, if you use the same disconnect to keep both PG&E safe and firemen safe... then PG&E would disable your home backup solution if they ever had to work on services near your home. I guess the "safest possible answer" is to provide firemen access to shut off your PV and batteries that is a separate item than the big lever box that PG&E requires.

I'm trying to see if fire-safety requirements also deny the use of molded case breakers...

Seems like overkill to do this, but then the inspectors can't poo poo on anything.

The thing is that PGE doesn't require an approved disconnect for this type of installation unless:
1. The meter to be installed is larger than CL320 (wont be on a 225A panel)
2. The meter is any type of Current Transforming (CT) meter (rare, most meters pass the amps directly through themselves, CT meters don't)
3. There is a line side tap
4. The Main Service enclosure is larger than a 400A unit
5. The service is 3 phase

Once you do have a required disconnect there is a narrow list of allowed ones, all of them are bladed lockable.

PGE does not control whether your rapid shutdown or equipment service disconnect is anything specific.

Molded case circuit breakers are allowed as a means of service disconnect and also as a means of rapid shutdown.
 
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