SAJ H2 Series Hybrid Solar Inverter (battery)

Installation

1. 1Enable Modbus TCP on the SAJ H2 inverter by connecting the AIO3 Wi-Fi module and confirming that port 502 is accessible on your local network via the eSAJ or AIO3 configuration interface.
2. 2Connect the ModbusCloud Gateway to the same LAN segment as the inverter, ensuring no firewall rules block TCP port 502 between the Gateway and the inverter IP address.
3. 3In the ModbusCloud portal, add a new device, import the SAJ H2 Series Hybrid Solar Inverter (battery) template, and enter the inverter IP address plus Modbus unit ID (typically 1).
4. 4Spot-check the connection by reading the soc register (address 40972) in the live data view and confirming the value matches the inverter display or the eSAJ app.

Things to watch for

01

No values appear even though the gateway shows connected.

Confirm the inverter's AIO3 module is online and port 502 is open. Some H2 firmware versions only expose Modbus TCP when the Wi-Fi module has an active cloud connection. Try polling with a Modbus TCP test tool from the same network segment to isolate the problem before adjusting portal settings.

02

The power register reads negative or unexpected values. Why?

Register 16550 is a signed int16. Depending on inverter firmware and metering direction, negative values may indicate power flowing into the battery or from the grid. Verify the sign convention in your installation against the inverter display and apply an offset or inversion in your dashboard channel if needed.

03

The energy counter resets or jumps unexpectedly after a restart.

Register 16597 is a uint32 cumulative counter. A full inverter power cycle or firmware update can reset this counter to zero. Store baseline readings in the portal at commissioning so historical totals remain accurate even after a counter reset.

04

Is it safe to write to the battery mode registers during normal operation?

Use the six writable batterymode registers (addresses 13895, 13905, 13828, 13830, 13831, 13832) with caution. Writing incorrect values can switch the inverter to an unintended operating mode, affect battery charge depth limits, or interfere with grid-protection settings. Always test writes during a controlled maintenance window and confirm the inverter returns to the expected state before leaving site.

Registers (9)

3 read / 6 write

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