The Gateway connects but all register values are zero or absent.

Modbus RTU is disabled by default on G4 models. Go to Settings, Advanced Settings, Modbus on the inverter display and confirm Modbus is active. Also check that holding register 0x013E (485CommFunSelect) is set to 0 for Modbus mode, not 1 for EV Charger mode.

RS-485 wiring is connected but no data appears after enabling Modbus.

RS-485 polarity is critical on Solax inverters. Confirm pin 4 (blue wire) connects to the A lead and pin 5 (white-blue wire) to the B lead on your adapter. Also verify that only one Modbus master is on the bus; a second master such as a Wi-Fi dongle or another integration will cause collisions and silent read failures.

Battery power reads plausible values but the sign seems inverted.

The power register (address 297) is a signed int16. Positive values indicate charging and negative values indicate discharging. If your portal shows the opposite, check whether a scaling or sign inversion is applied in your data pipeline before raising a hardware fault.

Is it safe to write to the batterymode registers frequently for automation?

No. The Solax holding registers used for battery mode control (addresses 31, 32, and 86) are stored in EEPROM, which has a limited write cycle life. Frequent automated writes, such as switching mode every few minutes, can degrade the EEPROM irreversibly. Restrict writes to genuine mode changes and avoid polling these registers with write commands on a short interval.

Free Modbus template: Solax Hybrid X1/X3 G3/G4 (battery)

The Solax Hybrid X1/X3 G3/G4 is a solar hybrid inverter family covering single-phase and three-phase residential and light-commercial installations with integrated battery storage support. This ModbusCloud template communicates over Modbus RTU via the inverter's RS-485 COM port and reads battery power flow and state of charge, while also exposing three holding registers that control battery operating mode. The Q.HOME ESS HYB-G3 is an OEM variant covered by the same register map. With live battery data and remote mode control in one template, installers can monitor storage health and adjust charge behaviour directly from the ModbusCloud portal.

Name	Address	Function	Type	Unit	Access
power Instantaneous battery power, positive = charging, negative = discharging.	297	FC04	int16	W	R
soc Battery state of charge, integer percentage.	301	FC04	uint16	%	R
batterymode_a Battery operating mode selector setpoint (self-use, feed-in priority, backup).	31	FC16	uint16		W
batterymode_b Secondary battery charge mode control register, paired with batterymode_a.	32	FC16	uint16		W
batterymode_d Tertiary battery mode or charge period control setpoint.	86	FC16	uint16		W

Solax Hybrid X1/X3 G3/G4 (battery)

Overview

Use cases

Installation

Things to watch for

Registers (5)

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