Sunsynk 3p hybrid inverter (grid)

Installation

1. 1Enable Modbus RTU on the Sunsynk 3p hybrid inverter by navigating to Advanced Settings and then Multi-Inverter on the inverter display; note the configured Modbus SN (unit ID, typically 1).
2. 2Connect the RS-485 A and B terminals on the inverter to the ModbusCloud Gateway using a twisted-pair cable; keep the cable run to the minimum practical length and avoid sharing the pair with high-voltage wiring.
3. 3In the ModbusCloud portal, add the Gateway, create a new device, import the Sunsynk 3p hybrid inverter (grid) template, and set the unit ID to match the Modbus SN configured on the inverter.
4. 4Verify the connection by spot-checking the power register (address 625): under a known load or during active solar production the value should be a non-zero signed integer consistent with measured grid flow.

Things to watch for

01

All registers read zero or return timeout errors. What is wrong?

Confirm the RS-485 A and B wires are not swapped. The idle voltage between A and B on the Sunsynk RS-485 port should be around 4 to 5 V with nothing connected. A reading near 0 V or constant timeout usually indicates reversed polarity or a missing common ground between the Gateway and inverter.

02

Phase current registers read garbage or implausibly large values. Why?

The Sunsynk 3p hybrid inverter stores phase currents as signed int16 with a scaling factor of 0.1 A per unit. If your polling stack is treating the raw register value as unsigned, negative currents will appear as large positive numbers. Confirm your Modbus client interprets these registers as signed 16-bit integers.

03

The Gateway connects but the energy register shows no change. What now?

Address 522 is a uint32 spanning two consecutive 16-bit Modbus registers. Verify your client reads two registers starting at address 522 and combines them in big-endian word order, which is the standard Sunsynk byte order. Reading only a single register at that address will return an incomplete and static-looking value.

04

RS-485 communication is unstable with random CRC errors. What should I check?

If your RS-485 adapter includes a 120-ohm termination resistor, try removing it. The Sunsynk RS-485 port is typically the only device on the segment and adding a termination resistor at both ends of a short cable can over-terminate the bus, causing signal reflections and intermittent CRC failures.

Registers (5)

5 read / 0 write

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