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Roadmap wish item: Powerwall/S3XY optimizations for charging

The recent software feature updates to charging behaviors when there is a grid outage is a good start.

But, something I would appreciate having the ability to do through software and associated communications is to charge my vehicle after and only after the Powerwalls have had their fill for the day.

Car is plugged in, Gateway/Powerwalls monitor PW-SoC, PW-SoC hits a user defined amount (100%?), car communicates with Gateway/API to determine current solar production and varies its own draw accordingly with an aim to not transfer PW-battery to EV-battery, car continues to vary its draw until solar production isn't sufficient or the EV-battery hits user defined charge limit, then normal grid-power/net-metering. User always has option to override charging behavior in the car to demand charging at any time (power from grid or Powerwalls).

Presently, my system will hit 100% SoC on the Powerwalls around 2pm daily depending on clouds. But, the only controls I have for when the car tries to charge itself is literally to plug/unplug the mobile charger or schedule a time for charging to start. I have to monitor for clouds or heavy house loads and stop/start charging if I want to only charge the car via solar production.

Writing out the above this seemed initially like more of a car behavior, but I think it could be better done (less code) by the Gateway side of the communication. The Gateway has all the necessary state information except for EV-battery charge state and EV charger connection state. Best for the Gateway to signal the car that it was ready to have the charge happen. The car already has an API for 'start/stop charging' let the Gateway signal the car when to begin or end.

This might be too niche of a use case though given my low daily miles (estimated at less than 20 miles/day?). My vehicle spends most of its day (sunlight hours) in its own garage; retired person. I assume most other drivers likely need more charge than what solar production could provide or can only charge when solar production is not possible (late day/night).

Personally, I am unreasonably happy with my solar production system that I can operate my house off-grid for seemingly months on end (self-powered) and drive my car on solar production only (manual process, watchful owner). Anything to make that easier for me to do only makes me more unreasonably happy.

Other ideas:

1) Allow for the prioritization of PW-SoC, EV-SoC, net metering by user choice. (This likely would supercede TOU tiering, but probably needs to be user selectable too) [Where do you want the electrons to go?]
2) Allow for permissible/preferred power sources for the vehicle charging: solar production only, solar production via Powerwall, grid power via Powerwall (storm watch for example), grid power only. [Custom: wind, wave, ...] [Multiple ordered priorities with consideration of TOU settings] [How green do you want your vehicle power? Or, which flavor of power do you want?]
3) Intelligent control of vehicle charging draw based on available solar production and weather forecast. [Given that certain weather apps can predict rain with minutes of accuracy, have the vehicle take that same information to predict when it should charge itself and at what rate of charge] [What's the weather like?]

What else would be nice to see Tesla add to the roadmap that involves both the vehicles and the energy systems?


Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
Riverside Co. CA
I like the term "unreasonably happy", lol. I also like some of your ideas. I like the idea of the car / powerwall / gateway system being intelligent enough to work together for the car to basically charge from "left over" solar after the powerwalls are charged,

Just like the PWs fill from left over solar under self powered, it seems like it would be possible for that left over solar to be shifted to a Tesla vehicle through the HPWC or car mobile charger, if connected, rather than sent to grid, until there was no excess or until the car was at its designated charge level.

It makes too much sense for it to work that way for it not to happen at some point, and would be another differentiator for tesla vs other systems (integration).

I feel at least that will come at some point.
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