The gateway connects but both registers always read zero.

Zero readings during daylight usually mean the inverter is in standby or the RS485 bus is wired incorrectly. Confirm the inverter is in normal operating mode, then swap the A and B wires at the Gateway end. Many SofarSolar installations require the A/B polarity to be reversed from what the label implies.

Why do I get a timeout error on every poll?

A timeout almost always points to a baud-rate or slave-ID mismatch. Confirm the inverter is set to 9600/8/N/1 and slave ID 1 in its communication settings, and that the Gateway unit ID in the portal matches. If you share the RS485 bus with a logger stick, it may be blocking the line.

The energy register value looks implausibly large or wraps unexpectedly.

The energy register is a uint32 spanning two consecutive holding registers. If only one 16-bit word is being read, the value will be wrong. Ensure your poll reads two registers starting at address 540, and that the portal template is set to uint32 (big-endian word order).

Communication was stable but stopped working after a firmware update.

SofarSolar has a documented history of register address changes between firmware generations. After an inverter firmware update, verify the slave ID and baud rate are still set correctly in the communication menu, and compare the power register reading against the inverter display to confirm address 533 still maps to PV power.

Free Modbus template: SofarSolar Hybrid Inverter (pv)

The SofarSolar Hybrid Inverter is a residential and light-commercial solar inverter with integrated battery management, connecting PV arrays, battery storage, and the grid in a single unit. This ModbusCloud template uses Modbus RTU to read two core PV-side registers from the SofarSolar Hybrid Inverter: instantaneous generation power and cumulative energy yield. With these readings flowing into your ModbusCloud portal, you can track solar output trends, verify system uptime, and generate yield reports without relying on a proprietary cloud service.

Name	Address	Function	Type	Unit	Access
power Instantaneous PV generation power output, in watts.	533	FC03	uint16	W	R
energy Cumulative PV energy generated, total lifetime production.	540	FC03	uint32	Wh	R

SofarSolar Hybrid Inverter (pv)

Overview

Use cases

Installation

Things to watch for

Registers (2)

Working with Modbus in your projects?

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SofarSolar HYD 3…6K-EP (battery)

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