The control in the Tesla app for off-grid car charging is only a go/no-go depending on Powerwall SOC. Tesla really should provide the ability to charge from surplus solar when the grid is up or down. People have been asking for this for a long time. It could be implemented in the car or the Gen3 Wall Connector.
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Best Way To Install Car Charger with PowerWalls?
- Thread starter ftrv8
- Start date
Vehicle Charging During Power Outage | Tesla Support
Powerwall now coordinates with Tesla vehicles during a power outage to charge your car without exceeding the energy and power capabilities of your Powerwall.
Earlier in the thread was a link to the Powerwall load shedding capability. I'm guessing that a sufficiently sized relay would be able to turn off an L2 outlet. Probably would want an override or similar in case you do want to use it during an outage.
eml2
Member
Tesla already provides ability to charge Tesla car from surplus solar when grid is down. It seems that the way it changes the charge rate (to match surplus solar) is via frequency curtailment. I observed (when off-grid) from local API (https://your-teg/api/meters/aggregates) that battery.frequency was in the range between 59.7 to 59.85 while my Model X charge rate varies. When it is on-grid, frequency is within a very close range between 59.99 and 60.01.
Since Tesla said that no internet connection is required to support car charging during power outage (Vehicle Charging During Power Outage | Tesla Powerwall), it is plausible that the car charger is using frequency to adjust charging rate. It may also be the only way to do so since Tesla never includes charging rate adjustment in the app.
One of the side effects of lowering frequency is that all my AC clocks will run slower (a few seconds) after a few hours. In addition, if this is the only way to adjust the charging rate, then it will never able to charge the car with only surplus solar (which requires constant charge rate adjustment) when on-grid.
Same here. We charge thru a 14-50 backed up connection. Right now with WFH it’s done during the day. We’ll add a number of miles at an Amp rate that let’s us charge from the sun with still some power going into the Powerwalls so we’re not drawing from them. With whole house back up for charging if we lose power we’ll still be able to add enough range to get to a Supercharger if need be for a longer needed trip. The SCs at least from past PSPSs in our area seem to be powered when areas around it weren’t.
Hi All,
Not sure if this will get a reply since this thread is a couple of years old, but the discussion here is closest to my situation so here goes…
I installed my 11.5kW Tesla panels last year with 2 PWs. The PWs are in my garage and they gave me a sub panel with 2 breakers (I think the breakers are for the PWs). My mains was already at 200A and all the house circuits are still on it.
I bought the Juicebox 40 charger thinking I would use a NEMA 14-50 outlet for it and have gotten multiple quotes for connecting it. All except one said they will add a 50A breaker on the mains, some recommended hardwiring a Juicebox 48.
Just one guy gave me a quote to add the 50A breaker on the sub panel in the garage.
So my question is…
1. Has anyone used that setup via the Tesla PW sub panel to connect their EV? Is that what it means to be on the backup side?
2. Any reason not to go with that setup?
3. Is that setup what is shown here Vehicle Charging During Power Outage | Tesla Support
Not sure if this will get a reply since this thread is a couple of years old, but the discussion here is closest to my situation so here goes…
I installed my 11.5kW Tesla panels last year with 2 PWs. The PWs are in my garage and they gave me a sub panel with 2 breakers (I think the breakers are for the PWs). My mains was already at 200A and all the house circuits are still on it.
I bought the Juicebox 40 charger thinking I would use a NEMA 14-50 outlet for it and have gotten multiple quotes for connecting it. All except one said they will add a 50A breaker on the mains, some recommended hardwiring a Juicebox 48.
Just one guy gave me a quote to add the 50A breaker on the sub panel in the garage.
So my question is…
1. Has anyone used that setup via the Tesla PW sub panel to connect their EV? Is that what it means to be on the backup side?
2. Any reason not to go with that setup?
3. Is that setup what is shown here Vehicle Charging During Power Outage | Tesla Support
I would install the Tesla HPWC (1st)or use the UMC with the NEMA 14-50 (2nd) so I keep the functionality integration with the Tesla Powerwalls, per your point 3. If you buy juicebox, you lose that integration.
The EV charger can be tied into any metered (backed up) subpanel or service panel, as long as all codes are followed. I can't be sure how your Powerwall subpanel is connected so I won't say go ahead there without some drawing or diagram.
Definitely make sure the electrician you hire is competent, and I would make sure they pull a permit.
Hi @Vines
Thank you so much for your reply.
If it helps explain my install, here’s the wiring diagram showing the 125A backup load center to which that licensed electrician said he can connect the Juicebox 40. I had called the Tesla Solar system HelpDesk after I got his quote and plan to check if that voids the Tesla warranty and was told that it would not.
But any insight here would help.
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What extra integration do you get with the Tesla EVSE? I use a non-Tesla unit and I still have the option in the app to select how much power to share during a power outage. I assume that's controlled by the car, not the charger. Are there more options with a HPWC?
With the Tesla ecosystem, you can program a battery reserve percentage for EV charging when off grid.
So in my home, my car will not charge until my Powerwall batteries are set at 90% charge. From there more solar production automatically dumps into my car charger, at a rate that matches the PV generation roughly.
Are you using ChargeHQ for that charging rate matching to PV-Gen?
So when do we get to see your new, wrapped Performance Y?
Are you sure this won't work with a non-Tesla EVSE? If it's controlled by a frequency shift, wouldn't the car still be able to detect it?
I am not using ChargeHQ, just the regular Tesla integration.
I went for a LR this time, not a performance, and I just got the wheels on. The wrap shop has a little work to do and then its time to take a few pics.
For now here is my new steering wheel leather wrap.
I am not sure it won't work, but the Tesla integration says that it will work with the UMC and HPWC.
If other chargers work that would be interesting to know.
Lol I guess I should have read your signature...
Tesla integration does "excess PV charging" via the app? Or are you doing something super next-level fancy using their API?
I'm still trying to figure out what to do with all this extra solar from the recent atmospheric river blowing some solar panels and micro-inverters onto my roof.
Currently, the app only does "Vehicle Charging while off grid" which does vary charge rate with pv irradiance.Lol I guess I should have read your signature...
Tesla integration does "excess PV charging" via the app? Or are you doing something super next-level fancy using their API?
I'm still trying to figure out what to do with all this extra solar from the recent atmospheric river blowing some solar panels and micro-inverters onto my roof.
In the future, I think the app is supposed to charge from sun while on grid to reduce NBC, but that's not deployed to my app yet.
Ooohhhh you're basically operating in "off grid" mode right now? Aren't you losing your NEM exports?
No, I am only referring to the off-grid behavior.
I basically charge at work 90% of the time anyway and let my PV and Powerwall system handle the details. We are definitely collecting some NEM 2.0 export credit.
Off grid behavior is independent of the EVSE used. I happen to have JB-40 for my EVSE and the feature is enabled for me.
As far as I know, Tesla has not implemented "surplus solar" charging yet. I don't think they need EVSE integration for this either (assuming Tesla cars)
Re: the original question, I would just be slightly cautious when adding loads to the sub panel to make sure you don't end up confusing the Powerwalls. Make sure the CTs know about the new load. In my case I had "generation" sub panel and each circuit there was a Powerwall or solar with their own CTs. I don't recall if there was separate CT for my separate "load" panel.
So when you are off grid and your home battery percentage exceeds the "Vehicle charging while off grid" percentage, then the juice-box 40 starts charging your Tesla at a rate proportional to the excess solar PV?
Interesting if so, and doesnt fully agree with this page:
Vehicle Charging During Power Outage | Tesla Support
Edit: I guess it does say "Any Wall Connector"
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