Fill Powerwalls first, Tesla EV second, extra to grid third?

[onautopilot]

Funny I was just thinking about this same thing last week. I'm also waiting for PG&E PTO. But I have my system on anyway.. Since they have implemented a similar feature for off grid, it would certainly be nice if it was available on grid. My attempt at a workaround is to set my car to charge at 11:00 am. I lowered the max charging rate to in the car to 30ish amps. Opposite of what I used to do. Seems to be working okay, when I'm actually at home at least..

 

[miimura]

Is there a difference in efficiency between charging at a reduced rate versus the maximum rate? I’ve been experimenting with lowering the amps in my Model 3’s charging UI so that I charge at 3-5 kW, and then I manually start/stop charging from the Tesla app during times of the day when I’m only charging via excess solar and not pulling from the Powerwalls. I have a gen3 TWC so it’ll be nice if Tesla implements this behavior automatically while on-grid like @Er1c* and @morph3ous discuessd.

In a Tesla, the primary difference in charging efficiency is caused by overhead loads. Keeping the car awake and running pumps takes energy. So, to the extent that charging takes longer, the energy consumed by those activities is "wasted" energy.

 

[kairojya]

In a Tesla, the primary difference in charging efficiency is caused by overhead loads. Keeping the car awake and running pumps takes energy. So, to the extent that charging takes longer, the energy consumed by those activities is "wasted" energy.

That’s a good point. I hadn’t considered the overhead load of just having the car awake while charging. Although, I recall being surprised at how low that load was, at least from learning about it via TeslaBjorn’s YouTube videos (via ScanMyTesla and his experiences).

Now I want to do some testing and see the total kWh (input) I use to charge the same SoC at 3 kW vs 11 kW.

I hadn’t considered this aspect of charging an EV while having a PV system and ESS. Specifically how quickly I can deplete my 27 kWh ESS in my setup. I don’t know why I feel differently about running down my Powerwalls to charge my car versus using 50%~ of their energy to power the rest of my home overnight.