Inverter Modbus Register 77: Friendly name Day Grid Export

Technical Definition

The register friendly name Day Grid Export at address 77 is used to monitor friendly name day grid export on the inverter.

• Protocol: Modbus RTU
• Data Type: U WORD
• Unit: kWh
• Access: Read Only

How to Read (Python pymodbus)

Use this code snippet to read this specific value via RS485:

from pymodbus.client.sync import ModbusSerialClient

client = ModbusSerialClient(method='rtu', port='/dev/ttyUSB0', baudrate=9600)
client.connect()

# Read friendly_name Day Grid Export (Address: 77)
# Note: Check if your device uses 0-based or 1-based addressing
result = client.read_input_registers(address=77, count=2, unit=1)

if not result.isError():
    print(f"Raw Value: {result.registers}")
else:
    print("Error reading register")

client.close()

Integration (Home Assistant)

Paste this into your configuration.yaml:

- platform: modbus_controller
  name: "friendly_name Day Grid Export"
  address: 77
  value_type: U_WORD
  unit_of_measurement: "kWh"

Connection Diagram

Here is the standard RS485 wiring for this configuration:

graph TD
    PLC[Host Controller / Home Assistant]
    Device[inverter]

    PLC -- "A+ (D+)" --> Device
    PLC -- "B- (D-)" --> Device
    PLC -- GND --> Device

💡 Engineer's Insight

Analysis: Measures the total energy (kWh) exported to the grid during the current day. Indicates daily surplus energy sent to grid.

Troubleshooting: Zero suggests no export. May occur if solar/battery supply meets demand. Check export limits and grid-tied status if export is expected.