Add battery storage and AC charge controls for Growatt MIN TL-XH

[sadegroo]

Add battery storage and AC charge controls for Growatt MIN TL-XH

Summary

Adds ESPHome controls for battery-first charging, AC (grid) charging, and time-slot scheduling on the Growatt MIN 2500-6000 TL-XH hybrid inverter series. These registers allow Home Assistant automations to trigger AC charging during cheap grid tariff windows.

Background

The Growatt Modbus RTU protocol document lists two separate holding register ranges for storage/battery control:

• Registers 1000–1120 ("Six group for Storage Power") — used by older MIX/SPH models
• Registers 3000+ ("Use for TL-X and TL-XH") — used by TL-XH series

On the MIN TL-XH, the 1000-range registers return Modbus exception 1 (Illegal Function) on any write attempt. The password/unlock mechanism described in the protocol (registers 135–138) also returns exception 1. These registers simply do not exist on TL-XH firmware.

The 3000-range registers accept writes directly without any unlock sequence.

What's added

Switches

Entity	Register	Description
AC Charge Enable	3049	Enable/disable grid-to-battery charging

What's changed

• Replaced non-functional register 1090 (Battery First Power Rate) with register 3047
• Replaced non-functional register 1091 (Battery First Stop SOC) with register 3048
• Replaced non-functional register 1092 (AC Charge switch) with register 3049
• Fixed entity names containing / (will become an error in ESPHome 2026.7.0)

What's NOT changed

All existing read-only sensors (PV power, AC output, energy totals, battery SOC, grid voltage/frequency, temperatures, fault codes) are unchanged. These use input registers that were already working correctly.

Testing

Verified on a Growatt MIN 5000TL-XH:

• Writes to register 3048 confirmed: value read back correctly after write
• Writes to register 1091 confirmed failing: Modbus exception 1 (Illegal Function)
• Writes to register 135 (unlock) confirmed failing: Modbus exception 1 (Illegal Function)
• Register 0 (On/Off, first group) confirmed writable — Modbus communication itself is functional

Automation example

To AC charge during a dynamic cheap-tariff window from Home Assistant:

automation:
  - alias: "AC charge during cheap grid power"
    trigger:
      - platform: state
        entity_id: sensor.cheap_power_active  # from your tariff integration
        to: "on"
    action:
      - service: number.set_value
        target:
          entity_id: number.growatt_battery_first_power_rate
        data:
          value: 100
      - service: number.set_value
        target:
          entity_id: number.growatt_battery_first_stop_soc
        data:
          value: 100
      - service: switch.turn_on
        target:
          entity_id: switch.growatt_ac_charge_enable

References

• Growatt Inverter Modbus RTU Protocol II V1.20 (English)
• Growatt MIN 2500-6000 TL-XH Installation Manual, Section 7.3