Growatt SPH Modbus Control

Verified Behaviour for Battery First / Grid First / AC Charge via Local Modbus RTU
Tested on Growatt SPH inverter using Home Assistant and pymodbus debug logs.

This document provides a confirmed and practical reference for controlling Growatt SPH hybrid inverters locally without cloud dependency.

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1. Register Types

Growatt SPH inverters expose two useful Modbus register types:

Input Registers (Function Code 04)

Read-only. Provide real-time inverter data:

• Battery voltage, SOC
• PV power
• Grid flow
• Load power
• Temperatures

These cannot be written.

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Holding Registers (Function Code 03/06/16)

Writable configuration registers:

• Battery First
• Grid First
• AC Charge
• Charge/discharge limits
• Time windows
• SoC limits
• Inverter enable

Not all holding registers are writable.
All registers referenced here are confirmed to work without password.

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2. Time Window Format

Growatt encodes timestamps in a single 16-bit register:

• High 8 bits = hour (0–23)
• Low 8 bits = minute (0–59)

Example:
09:30 → (9 << 8) + 30 → 0x091E

A window of 00:00–00:00 disables the feature.

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3. Battery First

Battery First uses three registers:

Register	Function
1100	Start time
1101	Stop time
1102	Enable (1=on, 0=off)

Behaviour:

• Takes effect immediately.
• Only operates inside the configured time window.
• No password is required.

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4. Grid First

Grid First requires additional configuration:

Register	Function
1080	Start time
1081	Stop time
1082	Enable (1=on, 0=off)
1070	Discharge power limit (required)
1071	Stop-discharge SoC (required)

Behaviour:

• Will not activate unless both 1070 and 1071 are set.
• Priority mode switches instantly when 1082 is set to 1.

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5. AC Charge

Register	Function
1090	Start time
1091	Stop time
1092	Enable (1=on, 0=off)

Behaviour:

• Works only during an active time window.
• Confirmed working even when Battery First is active.
• No detectable lock state on SPH.

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6. Priority Mode Logic

Growatt uses three modes:

• Battery First
• Grid First
• Load First

Rules:

• Battery First and Grid First cannot be active at the same time.
• If both are disabled, system defaults to Load First.
• Modbus writes override cloud/app settings immediately.

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7. Home Assistant YAML Examples

Set a time window

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1100
  values: "{{ [(9 << 8) + 30] }}"

Enable Battery First

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1102
  values: [1]

Full Grid First activation

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1080
  values: "{{ [(22 << 8) + 0] }}"

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1081
  values: "{{ [(6 << 8) + 0] }}"

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1070
  values: [3000]

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1071
  values: [20]

service: modbus.write_registers
data:
  hub: growatt
  slave: 1
  address: 1082
  values: [1]

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8. Example Switch in Home Assistant (Battery First)

- platform: modbus
  scan_interval: 30
  switches:
    - name: "Battery First"
      hub: growatt
      slave: 1
      address: 1102
      write_type: holding
      command_on: 1
      command_off: 0
      verify:
        input_type: holding
        address: 1102
        state_on: 1
        state_off: 0

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9. Troubleshooting

• Battery First enabled but no charging → time window not set.
• Grid First not working → registers 1070 and 1071 missing.
• AC charge inactive → 1090/1091 still at 00:00.
• Modbus write ignored → wrong register type or model-specific behaviour.

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10. Conclusions

• SPH supports full energy-priority control via Modbus.
• No unlock/password required for Battery First, Grid First, or AC Charge.
• Time windows are essential.
• Inverter responds instantly to local Modbus control.