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EV Charger on Non-Backed Up Panel Drawing from Powerwalls

GHTech

Member
Jun 28, 2020
95
33
Granada Hills, CA
Greetings,

When my 8.16 kW PV and 2 PW's were installed (Sep 2020), we went with backing up all the circuits, including the EV (Honda Clarity Electric) circuit. I just had Tesla come out to fix another issue, move the EV charger circuit from the backed up panel to the non-backed up panel. I was assuming that when the EV is charging that the power will come from the grid, or maybe the solar, but not the 2 Powerwalls. But, the house draw (while the EV is charging) is supplied by the solar and Powerwalls. Thoughts?

Regards,

GHTech
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
10,373
11,719
Riverside Co. CA
Greetings,

When my 8.16 kW PV and 2 PW's were installed (Sep 2020), we went with backing up all the circuits, including the EV (Honda Clarity Electric) circuit. I just had Tesla come out to fix another issue, move the EV charger circuit from the backed up panel to the non-backed up panel. I was assuming that when the EV is charging that the power will come from the grid, or maybe the solar, but not the 2 Powerwalls. But, the house draw (while the EV is charging) is supplied by the solar and Powerwalls. Thoughts?

Regards,

GHTech

Thats normal, if the CTs are connected that way. Its the way mine is. You can use the powerwalls to put energy into the car, provided the grid is up. When the grid is NOT up, that circuit wont work. No chance of the car draining your powerwalls if a power outage happens when you have scheduled charging at night, but you can still use your powerwalls (and solar) to charge your car.
 

GHTech

Member
Jun 28, 2020
95
33
Granada Hills, CA
@morph3ous and @jjrandorin,

Appreciate the info. I was hoping that the car will pull only from the grid, but I guess not. I assume that while charging from the solar and Powerwalls, will switch over to solar and grid, when the Powerwall reserve is reached. And when the sun goes down, the charging will continue using the grid.

Regards,

GHtech
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
10,373
11,719
Riverside Co. CA
@morph3ous and @jjrandorin,

Appreciate the info. I was hoping that the car will pull only from the grid, but I guess not. I assume that while charging from the solar and Powerwalls, will switch over to solar and grid, when the Powerwall reserve is reached. And when the sun goes down, the charging will continue using the grid.

Regards,

GHtech

Yeah thats how it works (for me on self powered anyway).

Note that, its certainly possible for it NOT to work this way and work the way you describe as well. I believe it depends on how / where the CTs are placed in relationship to load, etc. Like most of this stuff, since they are construction projects, there can be different setups between homes depending on sub panels etc.

My understanding is, if the gateway couldnt see that circuit, it would always charge from the grid, no providing powerwall (or solar) to it, nor would it count in your home usage statistics etc in the tesla app (but obviously would in billing from your utility).

I just set my car to charge in the middle of the night, and have my reserve on my powerwalls set to whatever I want it to be, which means that when I drive my vehicle, and it starts charging in the middle of the night, it quickly consumes whatever is left in my powerwalls down to my reserve, and keeps charging, at that point from the grid.

It finishes in the middle of the night as well, and my solar re fills the powerwalls in the morning. No idea how it works when not using self powered mode, though.
 
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sorka

Well-Known Member
Feb 28, 2015
8,250
6,019
Merced, CA
@morph3ous and @jjrandorin,

Appreciate the info. I was hoping that the car will pull only from the grid, but I guess not. I assume that while charging from the solar and Powerwalls, will switch over to solar and grid, when the Powerwall reserve is reached. And when the sun goes down, the charging will continue using the grid.

Regards,

GHtech

You can disconnect the CT from the EV charger circuit in you panel and then the GW2 won't know your using it and won't pull power from the system to push back into the grid side which ends up being used by the charger instead of pulling from the grid.

The downside to disconnecting the CT is that your house kwh usage won't be reflected in the Tesla app.

I'd call Tesla and ask them if they can configure the TEG GW to not pull from solar or powerwalls for non backed up loads.

Now if you only disconnect the CT, any time your using the charger AND exporting power to the grid, your EV charger will use that power first and again, Tesla will think it exported power to the grid that it didn't so if you're tracking costs and importing data to any platform that models your data usage, disconnecting the CT will throw everything off.

Also, if you do nothing and your in advanced mode off peak, you'll use only grid power to charge your ev anyways.
 

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