The gateway connects but all register values show zero or null.

Verify the LAN or WiFi+LAN module is installed, not the default WiFi-only dongle. The default WiFi module does not expose Modbus TCP. Also confirm the unit ID is set to 247, which is the GoodWe factory default, and that the inverter is powered up by DC or AC before polling.

Why does the soc register return an implausible value?

The soc register at address 39005 returns a raw uint16 with no scaling factor. Confirm your poll is using function code 3 and reading a single 16-bit word. Some tools default to 32-bit reads which merge adjacent registers and produce garbage. Re-read with exactly one register length.

Connection drops randomly after working for a few minutes.

A dynamic IP address on the LAN module is the most common cause. Assign a static IP to the module via your router DHCP reservation, or configure a fixed address in the module settings. Random reconnects can also occur if the inverter goes into standby; ensure DC voltage is present from the PV strings.

Is it safe to write to the batterymode_a and batterymode_b setpoint registers?

Write these registers with care. Writing an incorrect EMS mode value or an out-of-range power limit to batterymode_b can force the battery into continuous charge or discharge, potentially triggering BMS protection or voiding warranty. Always verify the intended mode value against GoodWe documentation before writing, and return the inverter to auto mode after testing.

Free Modbus template: GoodWe ET/EH/BH/BT Hybrid Inverter (battery)

The GoodWe ET/EH/BH/BT series are hybrid solar inverters with integrated battery storage management, designed for residential and light-commercial PV installations. This ModbusCloud template communicates via Modbus TCP and reads battery power flow and state of charge, while also exposing the EMS mode and EMS power limit setpoint registers for active battery control. Connecting the GoodWe ET/EH/BH/BT to ModbusCloud lets installers track real-time battery behavior and automate charge or discharge decisions directly from the portal.

Name	Address	Function	Type	Unit	Access
power Battery power flow, positive for discharge, negative for charge, in watts.	35264	FC03	int32	W	R
soc Battery state of charge, 0 to 100 percent.	39005	FC03	uint16	%	R
batterymode_a EMS operating mode setpoint, controls charge, discharge, or auto behavior.	47511	FC16	uint16		W
batterymode_b EMS power limit setpoint, maximum power for the active EMS mode, in watts.	47512	FC16	uint16	W	W