question

Set the ESS mode to "Keep battery charged". Nothing else should be needed.

Unfortunately that charges the battery. I’m looking for a mode that neither feeds-in or charges the battery.

Under what conditions will the battery charge?

When the cost of generation is cheap enough. If we use a tariff like octopus agile that changes every 30 mins, I’d be looking to run the system in 3 modes:

1.Low tariff - charge batteries

2. Expensive tariff - run house off batteries

3. Middle tariff - not cheap enough to warrant charging the batteries and not expensive enough to run the house off the batteries once inverter inefficiencies are taken in to account. In this mode, the system should sit idle ready to act as a UPS should the grid fail.

I have no problem coding the logic, just need to know what parameters to change to achieve the above 3 states.

• during "1.Low tariff - charge batteries"
  => set ESS mode to "keep batteries charged". This will immediate start charging the batteries from the grid with the max current allowed by the BMS.
• during "2. Expensive tariff - run house off batteries"
  => set to normal ESS-Mode (optimized, either with or without battery life); set grid-setpoint to 0W or slightly below zero watts in order to reduce grid usage the most. Note that there will be a slight feed in to the grid, when loads switch off as ESS-mode/the inverter is lagging behind a bit because of the ESS.loop in the Cerbo..
• during "3. Middle tariff"
  => set ESS Min-SoC% to the actual SoC%. In addition set DVCC limit Charge Current to 0A to prevent "accidental" charging if SoC drops a bit below Min-SoC (calculated by BMS) but/while grid is still available.

That’s very useful information. Thank you for the settings.