Fox: Feed-In First and predbat_best_soc_min causing expensive import peaks

[WhatIsThisAllAboutSilly]

Describe the bug
The FoxEss "Feed-In First" mode does not allow the battery to discharge, even when its above minimum SoC on grid, so in situations where the load > solar, it imports.

Given with some tariffs the import is significantly more than the export (e.g. cosy import at 32.05p/kWh vs say 12p export) means this is costing money that predbat can't 'see' due to looking at 30 min blocks.

I've tried switching switch.predbat_set_export_freeze_only and switch.predbat_set_export_freeze with no effect.

Expected behaviour
On Fox systems you should keep it in self-use mode but then stop the battery from charging by setting foxess_inv_max_charge_current to 0. Max SoC limit, or Force Charge limit does not stop the battery from charging, only foxess_inv_max_charge_current does.

Predbat version

v8.43.1

Environment details

• FoxEss H1-5.0-G2
• EP11-H

[WhatIsThisAllAboutSilly]

Trying this as a fix:

discharge_freeze_service:
- service: number.set_value
entity_id: number.foxess_inv_max_charge_current
value: 0
- service: select.select_option
entity_id: select.foxess_inv_work_mode
option: "Self Use"

[WyndStryke]

Feed-in first (= "Freeze Export" in predbat) works fine with my Fox setup, using modbus (In fact I try to use Feed-in first as much as possible because it is more efficient than self-use).

Can you attach your apps.yaml, predbat logs, plan, etc. You can find their download links on the dashboard page.

Are you using the Fox Cloud, or the Fox Modbus integration?

[WhatIsThisAllAboutSilly]

Modbus here too.

Are you sure that when your in feed-in first mode, SoC > Min on Grid and Load > Solar, you are using your battery? Definitely not the case for me.

In any case, I've solved it by doing:

With two scripts that are called:

alias: FoxESS Disable Battery Charge
sequence:
  - action: number.set_value
    target:
      entity_id: number.foxess_inv_max_charge_current
    data:
      value: "0.0"
description: ""


sequence:
  - action: number.set_value
    target:
      entity_id: number.foxess_inv_max_charge_current
    data:
      value: "30"
alias: FoxESS Enable Battery Charge
description: ""

[WyndStryke]

Are you sure that when your in feed-in first mode, SoC > Min on Grid and Load > Solar, you are using your battery? Definitely not the case for me.

Yep, just works for me, no problem. This is what I have.

  # Services to control charging/discharging
  # charge_start_service - Should be set to a service that is called when charging starts
  charge_start_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Force Charge"

  # charge_freeze_service - If your inverter supports charge freeze set to a service that starts this mode
  # The Back-up work mode does not exist on older firmware versions
  charge_freeze_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Back-up"

 # charge_stop_service - Should be set to a service that is called when charging/charge freeze stops
  charge_stop_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Self Use"

  # discharge_start_service - Should be set to a service that is called when force export (discharge) starts
  discharge_start_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Force Discharge"

  # discharge_stop_service - Should be set to a service that is called when export/export freeze stops
  discharge_stop_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Self Use"

  # discharge_freeze_service - If your inverter supports export freeze set to a service that starts this mode
  discharge_freeze_service:
    service: select.select_option
    entity_id: select.work_mode
    option: "Feed-in First"

What does it do if you select 'feed-in first' via the app? (putting predbat into read-only mode for the duration).

[WhatIsThisAllAboutSilly]

Then that is very odd then, I've reverted my config back to how it was (i.e. matching yours) and will see how it behaves this week...

[WyndStryke]

Then that is very odd then, I've reverted my config back to how it was (i.e. matching yours) and will see how it behaves this week...

Keep in mind that there can be differences in things like firmware versions etc. My firmware is probably about 4 months old, but feed-in first was still working with my previous firmware too (dating from late 2024).

[WhatIsThisAllAboutSilly]

OK, this issue appeared yesterday, however I now think its a FoxESS bug as today I forced a higher minimum reserve and it was fine.

So wondering if the inverter, even with SoC > Min SoC on grid, still applies a minimum further SoC before it'll allow battery discharge.

[WyndStryke]

There's the global min soc and min_soc_on_grid which takes effect when the mode scheduler is off, and then the min soc within the mode scheduler slot.

'Reserve' in predbat uses the min soc on grid setting, and can change it, as per the standard apps.yaml configuration. I doubt that is the issue because you'd be able to see the min soc changing if you put it onto a graph.

There's also the effect of cold weather, if it is close to zero the system will avoid discharging too far, but I doubt that is the issue right now. Similarly the stormwatch feature will charge the battery if it thinks that a storm is coming, but I doubt that is a factor too (only relevant if you have home backup configured, and have turned on the stormwatch feature).