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Inverter breaker tripping when both cars charging

I've had a situation twice in the last month when the breaker for one of my Tesla solar inverters will trip when both our Teslas are charging at the same time and each one is pulling 32A. I'm wondering if they installed the wrong size breakers on the inverter outputs. The sub-panel with the two breakers for the inverters has 30A breakers which then feed into the generation meter. The meter then feeds into a 100A breaker in the gateway. Something doesn't add up here. Why would there be a 100A breaker in the gateway but only 30A x 2 breakers feeding into it? I don't currently have the Tesla electrical plans so I can't verify if this was how it was originally designed. Can't the inverter generate 7.6kW? That's 32A and would need a larger breaker to handle the full output. Am I missing something here?

According to the Powerwall+ datasheet, the breakers should be 50A. Which would make a lot more sense with the 100A in the gateway. How did this pass inspection?!?
 
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I've had a situation twice in the last month when the breaker for one of my Tesla solar inverters will trip when both our Teslas are charging at the same time and each one is pulling 32A. I'm wondering if they installed the wrong size breakers on the inverter outputs. The sub-panel with the two breakers for the inverters has 30A breakers which then feed into the generation meter. The meter then feeds into a 100A breaker in the gateway. Something doesn't add up here. Why would there be a 100A breaker in the gateway but only 30A x 2 breakers feeding into it? I don't currently have the Tesla electrical plans so I can't verify if this was how it was originally designed. Can't the inverter generate 7.6kW? That's 32A and would need a larger breaker to handle the full output. Am I missing something here?

According to the Powerwall+ datasheet, the breakers should be 50A. Which would make a lot more sense with the 100A in the gateway. How did this pass inspection?!?
For what it is worth, on my PowerWalls (non plus) I have 30A breakers and my SolarEdge 7.6kw inverter has a 40A breaker.
 
My regular Powerwalls have 30A breakers, but I think that the Powerwall+ should have 50A based on the documentation. I really need to bug Tesla to send me the design documents so I can see what they thought they were installing. I already found other issues the 'professional' electrician made so I'm not really surprised unfortunately.

They ran 10AWG for the Powerwalls and 8AWG for the Powerwall+s. That plus the 100A breaker in the gateway makes me think this was a mistake.
 
That's at least the sixth mistake they made when wiring up my system...sigh. Here's the running list:

1) Missing CT on non-backup loads.
2) Wrong size breaker feeding/back-feeding gateway.
3) Wrong size breakers on four circuits in backup panel.
4) Missing handle ties on MWBCs in backup panel.
5) MWBC hooked up to the same phase.
6) Wrong size breakers on Powerwall+.

The utility inspector caught #2, but both them and the city inspector missed everything else.
 
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h2ofun

Active Member
Aug 11, 2020
3,700
891
auburn, ca
That's at least the sixth mistake they made when wiring up my system...sigh. Here's the running list:

1) Missing CT on non-backup loads.
2) Wrong size breaker feeding/back-feeding gateway.
3) Wrong size breakers on four circuits in backup panel.
4) Missing handle ties on MWBCs in backup panel.
5) MWBC hooked up to the same phase.
6) Wrong size breakers on Powerwall+.

The utility inspector caught #2, but both them and the city inspector missed everything else.
Inspectors usually catch nothing. Mine was approved with nm #6 wire with a 60 amp breaker. Code is only to 55. Still waiting to hear from the installer and when they are going to fix. I sure would hate to have to go back to the contractors board.
 
Sure enough, the plans called for 50A breakers on the inverters. Just sloppy work from the electrician and multiple inspectors.
Good electrical inspectors increase safety, I have to say. Unfortunately, not all of them are as thorough as they could be.

Same goes for electrical installers. A poorly done job can be a literal hazard down the road and hurt someone or cause damage.
 
That's at least the sixth mistake they made when wiring up my system...sigh. Here's the running list:

1) Missing CT on non-backup loads.
2) Wrong size breaker feeding/back-feeding gateway.
3) Wrong size breakers on four circuits in backup panel.
4) Missing handle ties on MWBCs in backup panel.
5) MWBC hooked up to the same phase.
6) Wrong size breakers on Powerwall+.

The utility inspector caught #2, but both them and the city inspector missed everything else.

And 7) Improperly secured conduit from the main panel to the gateway.

Status on issues:

1) Fixed after about three months of bugging them and missed appointments (main inverter was also offline for the same three months)
2) Fixed prior to PTO
3) Awaiting new breakers to fix
4) Will fix once parts for #3 arrive
5) Corrected myself by swapping two circuits in the backup panel
6) Corrected myself with new breakers
7) Fixed prior to PTO

So it's been a little painful, but the system is working great now. Was able to charge the 4 Powerwalls from 0-100% this week and still have a little left over to sell to the grid. And I learned a ton about the system along the way. The inverter issue appeared to be a SW/FW issue. Once they pushed an update it corrected itself. It just took them three months to actually try.
 

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