The power register reads zero even when the sun is shining. Why?

The SAJ R5 Series only produces output when it is in normal on-grid state. If the inverter is initialising, in standby, or reporting a fault, register 275 will legitimately read zero. Check the inverter's LED or LCD status before assuming a communication fault. Also confirm the adapter's baud rate matches the inverter port in use: 9600 bps for RS485, 115200 bps for RS232.

The gateway connects but neither register returns any value. What now?

Verify that the RS485 or RS232 adapter has obtained a fixed IP and is reachable from the Gateway on port 502. The SAJ R5 Series Modbus protocol uses half-duplex communication, so only one device can transmit at a time. If another device (such as a meter or data logger) shares the same RS485 bus, collisions will cause read failures. Try isolating the ModbusCloud Gateway as the only master on the bus.

Energy register 305 shows a value that looks far too large. Is scaling applied?

The SAJ R5 Modbus protocol transmits integer values with an implied scaling factor to represent decimal quantities. The energy register is a uint32 spanning two consecutive holding registers. If your portal value appears an order of magnitude too high or too low, confirm that the data type is read as a 32-bit unsigned integer (two registers, big-endian word order), not as two independent 16-bit values.

Which Modbus unit ID should I use for the SAJ R5 Series?

The default Modbus slave address is typically 1. On some installations it may have been changed via the inverter's communication settings menu or through the eSolar configuration tool. If unit ID 1 returns no response, use the inverter's LCD display or eSolar app to check the current address setting, then update the unit ID in the ModbusCloud portal to match.

Free Modbus template: SAJ R5 Series Solar Inverter (pv)

The SAJ R5 Series Solar Inverter is an on-grid photovoltaic inverter available in single-phase and three-phase variants, designed for rooftop and small commercial PV installations. This ModbusCloud template communicates over Modbus TCP via a RS485-to-Ethernet or RS232-to-Ethernet adapter and reads two core registers: instantaneous AC output power and cumulative energy production. With these readings centralised in your ModbusCloud portal, installers and asset managers can track live generation and long-term yield from a single dashboard without relying on SAJ's proprietary cloud service.

Name	Address	Function	Type	Unit	Access
power Instantaneous AC output power of the inverter, in watts.	275	FC03	uint16	W	R
energy Cumulative total AC energy generated since installation, watt-hours.	305	FC03	uint32	Wh	R