KOSTAL Plenticore G3 + BYD + Elli Charger 2 + evcc – EV charging and dynamic battery SoC control

Energy
1

Hello,

I am looking for some advice on how to improve the energy management of my PV system, home battery and EV charging using Home Assistant and evcc.

I am relatively new to Home Assistant, so I would especially appreciate advice on the best architecture for this setup rather than just a workaround.

My setup:

  • PV system: approx. 13 kWp, 50% east / 50% south-west
  • KOSTAL PLENTICORE G3 inverter
  • BYD home battery: approx. 13 kWh
  • KOSTAL Smart Energy Meter
  • Elli Charger Connect/Pro 2 wallbox with RFID and MID meter
  • Škoda Enyaq RS
  • Home Assistant running on Raspberry Pi
  • evcc for EV charging control
  • KOSTAL is integrated into Home Assistant and provides battery, PV and grid entities
  • Elli wallbox is connected via Wi-Fi and controlled by evcc via EEBUS

What I would like to achieve

My goal is to have one central control system. Ideally, I plug in and authorize the Enyaq and Home Assistant/evcc then takes care of the rest.

I would like to have these charging scenarios:

  1. PV surplus charging: Charge the Enyaq automatically when sufficient PV surplus is available.
  2. Fast/immediate charging: I want to be able to select “charge now”, but I do not want this to completely discharge my BYD home battery.
  3. Battery protection: During immediate EV charging, I would like to reserve e.g. 45% of the BYD battery for the house.
  4. Automatic stop: Ideally, if the BYD battery reaches this threshold during immediate EV charging, EV charging should stop instead of simply continuing with 11 kW from the grid.
  5. After EV charging has stopped, the BYD battery should immediately return to normal operation and be available for the house again.

What already works

Home Assistant can access the KOSTAL Battery min SoC setting. I tested changing it from its normal value to 45%, and the setting was also correctly changed in the KOSTAL system.

This successfully prevents the BYD battery from discharging below 45%.

However, this is not quite the desired solution: once the battery reaches 45%, the Enyaq simply continues charging from the grid. And if I manually stop EV charging while the KOSTAL minimum SoC is still 45%, the house also continues drawing electricity from the grid although there is still 45% energy in the battery.

So using the KOSTAL minimum SoC permanently is not suitable.

One possible Home Assistant solution might therefore be:

EV immediate charging starts → set KOSTAL min SoC to 45%
EV charging stops → restore KOSTAL min SoC to 5–10%

But an even better solution for me would be:

BYD reaches 45% while EV is charging → Home Assistant tells evcc to stop EV charging → KOSTAL/BYD remains in normal operating mode.

Is this the approach you would recommend?

Second issue: Elli Charger / evcc

There is another problem which may be related to evcc/EEBUS rather than Home Assistant.

I have confirmed that evcc can reliably STOP the Elli wallbox. If the car is charging and I select “Off” in evcc, charging stops immediately.

Starting/re-enabling charging is less reliable.

I have received this message in the evcc log:

Skoda Enjaq RS: charger out of sync: expected enabled, got disabled

The debug log then also shows repeated vehicle wake-up attempts, for example:

wake-up vehicle, attempts left: 5

In practice, I sometimes have to use both the Elli app and/or Škoda app to get charging started. My goal would obviously be to avoid this and let Home Assistant/evcc control the process.

My questions

  • What would be the best Home Assistant architecture for this setup?
  • Is it better to dynamically change KOSTAL Battery min SoC, or should HA simply monitor BYD SoC and tell evcc to stop the charger at the defined threshold?
  • Can the evcc charging mode (off, now, pv, etc.) be reliably controlled from a Home Assistant automation?
  • How would you implement a simple “Charge now with home battery protection” button in Home Assistant?
  • Does anyone use a similar combination of KOSTAL PLENTICORE + BYD + Elli Charger 2 + evcc?
  • Has anyone seen the evcc/EEBUS error charger out of sync: expected enabled, got disabled with an Elli charger?
  • Is there a better way to handle Elli RFID authorization so that after plugging in/authorizing the car, Home Assistant/evcc can take over completely?

I can provide screenshots of the available Home Assistant entities as well as detailed evcc debug logs if helpful.

Ultimately, I would like the system to be as simple as:

Plug in Enyaq → authorize → select PV charging or “Charge now” → Home Assistant/evcc manages PV, home battery protection and charging automatically.

Any advice would be greatly appreciated. Thank you!

German replies are also very welcome :slight_smile: