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.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 2, read only
- Brand
- SAJ
- Last updated
Registers (2)
2 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| energy | Wh | Read |
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Use cases
- Monitor instantaneous AC output power to verify the SAJ R5 Series is performing within expected generation ranges during daylight hours.
- Track cumulative energy production over time to calculate yield ratios and identify performance degradation across a PV portfolio.
- Alert on sustained low power output during peak solar hours to detect shading, soiling, or inverter faults early.
- Compare daily energy totals across multiple SAJ R5 Series sites to benchmark installation performance and spot outliers.
- Report monthly generation figures automatically from the portal to support feed-in tariff administration or tenant billing.
Installation
Connect an RS485-to-Ethernet adapter to the RS485 port on the SAJ R5 Series inverter, or an RS232-to-Ethernet adapter to the RS232 port, and assign the adapter a fixed IP address on your local network.
Ensure the ModbusCloud Gateway is connected to the same LAN as the adapter, then add the Gateway in the ModbusCloud portal under Settings and assign it to the correct site.
In the portal, navigate to Devices, select Add Device, search for the SAJ R5 Series template, and import it. Enter the inverter's IP address, set the TCP port to 502, and confirm the Modbus unit ID (default is typically 1).
Trigger a manual poll in the portal and verify that registers 275 (power) and 305 (energy) return plausible values. Cross-check the power reading against the inverter's local display or SAJ eSolar app to confirm correct mapping.
Things to watch for
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.
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