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Off-Grid Solar Management

Home AssistantESP32Must/Growatt InvertersPylontech BMS

POWER_GRID: DISCONNECTED (ISLAND MODE)

True technological sovereignty requires energy autonomy. This project outlines the architecture of an isolated (Off-Grid) photovoltaic system managed entirely via software.

Base Hardware

  • Hybrid Inverters: Must / Growatt.
  • Lithium LiFePO4 Battery Banks: Pylontech.
  • Solar Arrays: Configured in series/parallel to maximize MPPT voltage.

Telemetry and IoT Integration

The biggest issue with commercial inverters is their stock monitoring software (slow, dependent on third-party clouds, not customizable).

The solution: Extract data directly from the RS485/CAN port.

Using ESP32 microcontrollers flashed with ESPHome, we intercept the serial communication between the inverter and the battery.

# ESPHome Modbus register mapping example
sensor:
  - platform: modbus_controller
    modbus_controller_id: inverter
    name: "Battery Voltage"
    address: 10005
    value_type: U_WORD
    unit_of_measurement: "V"

All this telemetry flows into Home Assistant, where custom Python automations dynamically decide whether to trigger heavy loads (water pumps, backup runs, secondary nodes) based strictly on solar production surplus.