Register 13021 always shows large positive values. Why?

Older Sungrow SH Series firmware returns battery power at address 13021 as an always-positive uint16. After firmware updates released around late 2024, the value became a signed int16 indicating direction. Ensure the template data type matches your firmware version. If in doubt, read the battery running state register (13000) to determine charge or discharge direction independently.

Modbus TCP connects but no register values appear in the portal.

Verify that Modbus TCP is explicitly enabled in the WiNet-S or inverter web interface. Even though some units ship with Modbus TCP active, the setting can reset after a firmware update. Confirm the device IP address is reachable from the ModbusCloud Gateway, and that the unit ID is set to 1. Sungrow uses big-endian word order; mismatched byte order will produce nonsense values rather than no values.

Write commands to battery mode registers have no effect. What is wrong?

Forced charge or discharge via the batterymode registers only takes effect when the EMS mode register (address 13049, batterymode_b) is first set to 2 (force mode). Sending a charge or discharge command to address 13050 while the EMS is still in normal mode (0) will be silently ignored by the inverter.

Is it safe to write charge or discharge setpoints remotely without restrictions?

Use caution when writing to the batterymode registers. Setting power setpoints beyond the inverter's or battery's rated limits can trigger protection faults and may affect warranty compliance. Always confirm the maximum charge and discharge power for your specific SH Series model and battery combination before sending setpoints via the portal, and include safeguard checks in any automation that writes to these registers.

Free Modbus template: Sungrow SH Series Hybrid Inverter (battery)

Name: Sungrow SH Series Hybrid Inverter (battery)
Brand: Sungrow
SKU: b12b4d52-7dcc-46a2-90ac-ba067fe43f5f

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Free Modbus template: Sungrow SH Series Hybrid Inverter (battery) | ModbusCloud

Registers (9)

5 read / 4 write

Name	Address	Function	Type	Unit	Access
power_in_config_a Battery running state, encoded status flag from the inverter.	13000	FC04	uint16		R
power_in_config_b Battery current, signed, tenths of an ampere.	13020	FC04	int16	A	R
power_in_config_c Battery power, signed watts, positive when charging.	13021	FC04	int16	W	R
energy Total battery discharge energy, cumulative, tenths of a kilowatt-hour.	13026	FC04	uint32	kWh	R
soc Battery state of charge, percentage of usable capacity.	13022	FC04	int16	%	R
batterymode_a Charge or discharge command: 170 charge, 187 discharge, 204 stop.	13050	FC16	uint16		W
batterymode_b EMS mode selection: 0 normal, 2 force charge or discharge mode.	13049	FC16	uint16		W
batterymode_c Secondary EMS mode control register for battery operation.	33047	FC16	uint16		W
batterymode_i Charge or discharge power setpoint in watts for forced EMS mode.	13051	FC16	uint16	W	W