Tesla to add the ability to Charge EV with excess solar

[CrazyRabbit]

Just got off the phone with Tesla support. This is brand new to them, and yep, they are finding some bugs, and the docs might not be the best wording.

They told me you can only enable one GW at a time. I guess could make sense.

But the key question, that he could not answer, is what is "excess solar"? How is it measured? He stated lots of folks
want control with PW charge status, before the car gets, which it does not have now, and the dev team may not be open to
put in for some reason.

So, at the moment, I told him I see no value since it does not have enough control and flexibility in my situation.

But again, what are they measuring to define "excess solar"? Maybe if I know this, it might answer some questions for me?

Excess solar means:
If battery charge below reserve:
PW first, home loads, vehicle then grid.
If battery charge above reserve:
Home loads first, vehicle second, PW third then grid.

 

[CrazyRabbit]

It really doesn't matter where your car charging is connected. What really matters is where your Grid CTs are placed. When my PW system was first installed, the Grid CTs were placed on the Gateway 1 switch at the grid input. That meant that the system was blind to the loads that remained in my main panel like my EV charging. This was not a big deal at the time, but I knew that I would be installing air conditioning in the main panel that I would want to offset with Powerwall energy, so I needed to measure the total grid draw closer to the meter. I opened a case with the third party installer and they moved the Grid CTs to the conductors between the main breaker and the breaker bus in the main panel. The PW Gateway is fed by a breaker in the main panel.

Long story short, my EV charging is not backed up, but the Powerwall system can measure my total grid draw and when it wants to zero out the total house load, it can. I would like the Charge on Solar feature to tell the car to absorb all the power that would otherwise be exported to the grid during Off Peak. That means, charge the Powerwalls first and only start the car charging after the PWs stop or reduce charging to the point that grid export begins. I also have a non-Tesla EV so this Charge on Solar thing isn't going to work for that car either. I'm pretty sure the car has to vary the charging current based on data from the Tesla cloud, not using the Wall Connector or something to signal the car through the charge port.

Everyone is different. Since we have no control on charge lvl of Powerwall I would like to see vehicles charge first. incase I go off grid, I don’t want to see solar shut off because powerwalls are full.
If you are willing to change your reserve level you can make powerwalls charge first, 100% backup.

 

[h2ofun]

Excess solar means:
If battery charge below reserve:
PW first, home loads, vehicle then grid.
If battery charge above reserve:
Home loads first, vehicle second, PW third then grid.

That is what I assume and therefore have no interest.

 

[h2ofun]

Everyone is different. Since we have no control on charge lvl of Powerwall I would like to see vehicles charge first. incase I go off grid, I don’t want to see solar shut off because powerwalls are full.
If you are willing to change your reserve level you can make powerwalls charge first, 100% backup.

I just will use my manual process, much simpler

 

[jjrandorin]

Excess solar means:
If battery charge below reserve:
PW first, home loads, vehicle then grid.
If battery charge above reserve:
Home loads first, vehicle second, PW third then grid.

Thats how I read all the information as well (thanks for summarizing).

For me personally, I would want "excess solar" to mean "solar generation after my powerwalls are completely full, regardless of my reserve setting."

I just got all the firmware versions for this now (at least for my wifes model Y), and once I read through it and saw "excess solar" ment "any solar past the reserve" I decided I wouldnt even walk through setting it up.

In fact, I would imagine that for "most" of the people who got powerwalls, they would prefer their powerwalls filled before their car got power. If you are willing to spend what these things cost, you have put some value on the resiliency aspect, and 1/2 a powerwall status just to fill your car with "clean energy" but not fill your powerwalls doesnt sound like something most people with powerwalls would want.

Hopefully at some point they put in a toggle or something that says "prioritize powerwall " or something else that lets you tell it "hey fill my powerwalls to 100%, always, before you start sending any power at all to my car.

I would love to be able to send "excess solar after my powerwall is filled" to my car, but I am not interested in the slightest at sending "excess power after powerwall reaches its reserve setting (50% in my case right now) to the car, leaving the powerwall at 50%".

 

[wwu123]

Or alternatively, there are some EVSE's from Solar Edge, Enphase, and Emporia that can take a CT reading of energy going back across the meter. The EVSE then instructs the EV (doesn't need to be a Tesla) to charge at a rate to soak up that energy. Those options may make more sense than relying on the Tesla App.

It's funny, there are already several vendors with EVSE's that charge with excess solar, just need a CT right at the meter. The definition of "excess solar" seems to be pretty standard among them, it's just what would be exported at the meter, and that works fine with post NEM1-type rate schedules, by minimizing exports. They can all work in conjunction with Powerwalls, they just aren't aware of the Powerwall behavior, whatever the Powerwall is doing is just part of net home consumption/generation.

Now Tesla won't do such as feature, for lack of a $50 CT, for solar users whether Tesla or third-party, without a Powerwall. But if you have a Powerwall, then you in most cases have that $50 CT at the meter (not the gateway). But suddenly the logic of "excess solar" seems to be complicated, and arbitrary, to different people. Why not just have Powerwalls do their logic modes the same way they always do and without regard to the new feature, and have "excess solar" be the same thing that every other vendor with a $50 CT defines it as?

 

[miimura]

It's funny, there are already several vendors with EVSE's that charge with excess solar, just need a CT right at the meter. The definition of "excess solar" seems to be pretty standard among them, it's just what would be exported at the meter, and that works fine with post NEM1-type rate schedules, by minimizing exports. They can all work in conjunction with Powerwalls, they just aren't aware of the Powerwall behavior, whatever the Powerwall is doing is just part of net home consumption/generation.

Now Tesla won't do such as feature, for lack of a $50 CT, for solar users whether Tesla or third-party, without a Powerwall. But if you have a Powerwall, then you in most cases have that $50 CT at the meter (not the gateway). But suddenly the logic of "excess solar" seems to be complicated, and arbitrary, to different people. Why not just have Powerwalls do their logic modes the same way they always do and without regard to the new feature, and have "excess solar" be the same thing that every other vendor with a $50 CT defines it as?

Exactly. "Excess solar" is solar that would otherwise be exported to the grid. Period.

Of course, "Charge on Solar" is not the same thing, but there should be a toggle for the behavior to be only "Excess Solar" above the car's grid charge setpoint.

 

[swedge]

For me personally, I would want "excess solar" to mean "solar generation after my powerwalls are completely full, regardless of my reserve setting."

I just got all the firmware versions for this now (at least for my wifes model Y), and once I read through it and saw "excess solar" ment "any solar past the reserve" I decided I wouldnt even walk through setting it up.

JJ,

Well said! I, for one, would appreciate it if you would try it out and confirm that it actually does what they say it does.

Interestingly, as long as the grid is alive which it usually is, the PW won't discharge below the reserve. So if I understand the second definition of excess solar ("any solar past the reserve") this would usually be equivalent to "any solar", which seems a bit odd. And when the gird is down, I won't be concerned about NBCs on imports and I'll want PW to top up anyway. This makes me wonder if the solar car charging behavior is different when on and off grid.

I have been car charging both before the PW and after PW, depending on my need to use the car. In either case, I want the PW at 100% at 3 when our rate goes up. To manually charge the car first, I turn off the PowerWall with the on/off rocker switch. (So far I have remembered to turn it back on, but I'm sure I'll forget one of these days.). So I'm not real sure which definition of excess solar I will prefer.

 

[h2ofun]

Thats how I read all the information as well (thanks for summarizing).

For me personally, I would want "excess solar" to mean "solar generation after my powerwalls are completely full, regardless of my reserve setting."

I just got all the firmware versions for this now (at least for my wifes model Y), and once I read through it and saw "excess solar" ment "any solar past the reserve" I decided I wouldnt even walk through setting it up.

In fact, I would imagine that for "most" of the people who got powerwalls, they would prefer their powerwalls filled before their car got power. If you are willing to spend what these things cost, you have put some value on the resiliency aspect, and 1/2 a powerwall status just to fill your car with "clean energy" but not fill your powerwalls doesnt sound like something most people with powerwalls would want.

Hopefully at some point they put in a toggle or something that says "prioritize powerwall " or something else that lets you tell it "hey fill my powerwalls to 100%, always, before you start sending any power at all to my car.

I would love to be able to send "excess solar after my powerwall is filled" to my car, but I am not interested in the slightest at sending "excess power after powerwall reaches its reserve setting (50% in my case right now) to the car, leaving the powerwall at 50%".

Yep, unless this way, not thanks. The tech person I talked with told me they are all pushing back on the tesla development team to add this but implied so far they are not interested for some reason.

 

[CrazyRabbit]

Thats how I read all the information as well (thanks for summarizing).

For me personally, I would want "excess solar" to mean "solar generation after my powerwalls are completely full, regardless of my reserve setting."

I just got all the firmware versions for this now (at least for my wifes model Y), and once I read through it and saw "excess solar" ment "any solar past the reserve" I decided I wouldnt even walk through setting it up.

In fact, I would imagine that for "most" of the people who got powerwalls, they would prefer their powerwalls filled before their car got power. If you are willing to spend what these things cost, you have put some value on the resiliency aspect, and 1/2 a powerwall status just to fill your car with "clean energy" but not fill your powerwalls doesnt sound like something most people with powerwalls would want.

Hopefully at some point they put in a toggle or something that says "prioritize powerwall " or something else that lets you tell it "hey fill my powerwalls to 100%, always, before you start sending any power at all to my car.

I would love to be able to send "excess solar after my powerwall is filled" to my car, but I am not interested in the slightest at sending "excess power after powerwall reaches its reserve setting (50% in my case right now) to the car, leaving the powerwall at 50%".

Charge on solar uses Powerwall to balance out zero, so as implemented Tesla wouldn’t want to charge PW all the way to 100%.
But I would want to see four tiles (home loads, PW, Vehicle, grid) and let you stack them in your priority. PW would probably need a charge level slider 0-95% leaving 5% for netting the system, then after vehicle is at charge limit would it top out PW.

 

[Rocket_man]

I agree. But sometimes, I know I will need the car during those few hours between full PW and rate increase. While I am doing things manually still, I sometimes turn the PW off (using the rocker switch) in the morning and slow charge the car. When I leave with the car, obviously I unplug it, but also turn the PW back on. Frankly, I don't expect the Charge on Sunshine to guess when I'm gonna need the car.

I just received my first NEM2 true-up, and NBC's were determinative. (I think this was an error, as discussed in another thread.) But the details of how and when charging the car on solar affects the true-up is still a question mark for me. More head scratching in my future...

As for discharging the car to the grid, the inverter in the car is not capable of grid-tied exporting. My Enphase micro-inverterters can do it, as can the electronics in the PowerWall, so it is clearly possible. But not with the electronics in current Tesla cars.

I do this a different way. Note the state of charge of your PW. Say it is 65%. Go into Settings and change your reserve to 65%. Then start your car charging. Once you are done charging the car go back in the Setting and set your reserve back to 20%. I sometimes forget this last step and leave the PWs at 65% through the night. I'd like Tesla to build in a switch to just allow the system to do this on its own. "Use PW to charge Car? Yes/No" is a simple setting that would avoid this manual step and would be all I need.

At this time of year with the AC's running at high duty cycles, my PW's hit the 20% reserve by 1 am. So I've set the car to begin charging at 1:30 am so by then the PW's won't go below 20%. If the grid goes down overnight I might be screwed if the car is still wanting to charge. But that is not a big risk for me. But this is another good example of why a simple setting 'Use PW to Charge car' would be a great feature to have. I NEVER want to use the PWs to charge my car.

 

[Rocket_man]

I got home early on Friday and my panels were still generating, so I plugged my car into the Tesla Wall Charger. I have my car scheduled to charge at 1:30 am. I do this to avoid pulling power from the PW's to charge the car. After plugging in the car, I got this new screen pop up and the car began Charging on Solar. When I set up the feature you can set the location where to Charge on Solar. Obviously at my home right? Where else can I Charge on Solar? I have a M3 RWD with LFP batteries so I set the limit to 100% and 32 amps is the max the car can charge. It began charging and I got tied up with something else and didn't monitor it very well. It was in the afternoon and I did notice I some messages that said it was waiting for Solar implying there was not enough power to keep charging.

I just left the car plugged in overnight and I assumed it would finish the charge at 1:30 and this morning I'd have 100%. But that is NOT what happened....

 

[power.saver]

I got home early on Friday and my panels were still generating, so I plugged my car into the Tesla Wall Charger. I have my car scheduled to charge at 1:30 am. I do this to avoid pulling power from the PW's to charge the car. After plugging in the car, I got this new screen pop up and the car began Charging on Solar. When I set up the feature you can set the location where to Charge on Solar. Obviously at my home right? Where else can I Charge on Solar? I have a M3 RWD with LFP batteries so I set the limit to 100% and 32 amps is the max the car can charge. It began charging and I got tied up with something else and didn't monitor it very well. It was in the afternoon and I did notice I some messages that said it was waiting for Solar implying there was not enough power to keep charging.

I just left the car plugged in overnight and I assumed it would finish the charge at 1:30 and this morning I'd have 100%. But that is NOT what happened....
View attachment 960651

You have to move the yellow slider to 100% if you want to have it charge to 100% after there's no more solar. As you have it set, the charge limit is only 40% with grid charging.

 

[Rocket_man]

This morning I checked the Tesla App and the car was at 87%. It looks like Charge on Solar overrides any schedule you may have set for your car. Maybe some people would want this, but if I had plans this morning and I wanted a 100% charge when I woke up I might be a little annoyed.

Checking the app I see a new display. It shows my car in the garage and I'm putting 4 kW into the car from Solar. Also I see that my PW's have only gained 3% from last night. It has been a cloudy day. My panels can produce 12-13 kW on a sunny day. The car was at 87%. It doesn't show that on this display. I went into the car app and I reduced the charge rate down to 20 amps and it did reduce the power going into the car. But since I wanted my PWs to charge up I shut off the Charge on Solar.

So you can see how it works. I'm not sure how it benefits me. I'd much rather have a setting "Charge car using PWs Yes/No" instead of this feature. For the longest time Tesla seemed to be oblivious to the fact that many Telsa car owners also have Tesla Solar and even in the same app one didn't know the other existed. Now that Tesla seems aware that there are a lot of customers like this (yes I'm being sarcastic) maybe there will be more features that integrate the car and solar in the app. This really doesn't benefit me since it takes my PW's out of my dailing charging routine. I have a higher priority need for my PW's than I do for the car. This is an obvious setting. Maybe someone who actually owns these products should be in charge of developing the app.

 

[Rocket_man]

You have to move the yellow slider to 100% if you want to have it charge to 100% after there's no more solar. As you have it set, the charge limit is only 40% with grid charging.

Ok, thanks. I completely misunderstood that slider setting.

Also after shutting this off... I just noticed it had started Charging on Solar again. I had to turn it off again. My PW's are only at 38% but getting 8.7kWs.

 

[swedge]

Maybe someone who actually owns these products should be in charge of developing the app.

That looks like a new graphic, showing the car in the garage. Maybe what happened is they let a graphic designer specify how the new feature works. ;-)

I am actually please to see them making improvements. The addition of Export Everything helped a lot in keeping my true-up down, even though we added a Model Y to our consumption. Hopefully they will continue to refine the software even more.

 

[buckets0fun]

That looks like a new graphic, showing the car in the garage. Maybe what happened is they let a graphic designer specify how the new feature works. ;-)

I am actually please to see them making improvements. The addition of Export Everything helped a lot in keeping my true-up down, even though we added a Model Y to our consumption. Hopefully they will continue to refine the software even more.

I had high hopes for the export everything option. Something to automate it, ‘export everything until X% because we know you use that much for the house until off peak. Not to mention we realize you want the reserve you had setup for power outages to remain.’

Home assistant is sounding better and better…

 

[Rocket_man]

It turned on again. It looks like just tapping 'stop charging' only stops charging until the system checks again to see if there is enough solar to charge the car. Then it automatically starts charging again from solar. I I had to just disable the feature to get my PW's charged up. PW's at 56%. Probably won't get to 100% today.

 

[phsoccer]

It turned on again. It looks like just tapping 'stop charging' only stops charging until the system checks again to see if there is enough solar to charge the car. Then it automatically starts charging again from solar. I I had to just disable the feature to get my PW's charged up. PW's at 56%. Probably won't get to 100% today.

I’m still waiting on the car to update so I can try this. Is it easy to wait until the PWs are near 100% and just turn it on? This would not be that different from the way I do it now where I manually tell the car to start charging as soon as my system starts exporting power. Hopefully this will be easier than me watching to raise and lower the charging amps as the panels change how much they are generating throughout the day.

 

[Rocket_man]

I’m still waiting on the car to update so I can try this. Is it easy to wait until the PWs are near 100% and just turn it on? This would not be that different from the way I do it now where I manually tell the car to start charging as soon as my system starts exporting power. Hopefully this will be easier than me watching to raise and lower the charging amps as the panels change how much they are generating throughout the day.

That is pretty much how I do it already. If my PW's get to 100% while the sun is still out I can test how this works. If it pulls from the PWs to charge the car, or it redirects the energy it would have exported to the car instead. This is how I would have wanted/expected it to work.

In the big picture, since I have thousands of banked kWh with my power company it doesn't cost me to charge the car from the grid. So for me this seems like more a gimmick. Others may find it useful. Maybe in a grid down condition it might be helpful, but in this situation I definitely want my PW's charged to 100% and stay there.