SMA - Sunny Boy Storage 2.5

Use cases

• Monitor battery state of charge and charge or discharge power on a live cloud dashboard for residential customers.
• Create alerts when battery state of charge drops below a critical threshold to prevent deep discharge events.
• Track grid feed-in and grid reference values over time to optimize self-consumption strategies.
• Remotely adjust the feed-in management operating mode to comply with updated grid operator requirements.
• Generate weekly or monthly energy storage reports for end customers without visiting the site.
• Compare active power and battery capacity trends across multiple SMA Sunny Boy Storage installations.

Installation

1. 1Connect the ModbusCloud gateway (MCG or MLP series) to the SMA Sunny Boy Storage 2.5 via RS485 wiring, observing correct A, B, and GND terminal assignments.
2. 2Set the Modbus RTU baud rate to 9600 and parity to odd on both the gateway and the inverter to ensure matching communication parameters.
3. 3Enable Modbus RTU communication in the SMA inverter settings menu and assign a unique Modbus slave address.
4. 4Configure the same slave address on the ModbusCloud gateway so it polls the correct device on the bus.
5. 5Import the SMA Sunny Boy Storage 2.5 template in the ModbusCloud platform and assign it to the gateway.
6. 6Verify live data appears on the ModbusCloud dashboard and confirm that register values match the inverter display.

Things to watch for

01

The gateway cannot communicate with the inverter. What should I check?

Verify that the RS485 wiring is correct (A to A, B to B, GND to GND). Confirm that both the gateway and inverter are set to 9600 baud with odd parity. Make sure Modbus RTU is enabled in the inverter configuration menu.

02

The BMS operating mode register returns no data or an error. Is this normal?

The BMS operating mode read register may be unsupported or a placeholder on certain firmware versions. Check the SMA documentation for your specific firmware and update if necessary.

03

Values appear but seem incorrect or out of range. What could cause this?

Registers on the SMA Sunny Boy Storage 2.5 use uint32 and int32 types that span two consecutive registers. Ensure the byte order and word order settings in the gateway match the SMA register specification. Also verify that register addresses have not shifted due to a firmware update.

04

Can I connect multiple SMA inverters on the same RS485 bus?

Yes, assign a unique Modbus slave address to each inverter and add a corresponding device entry in the ModbusCloud platform for each one. Use proper bus termination on the first and last device.

Registers (18)

17 read / 2 write

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