Wattsonic wattsonic (battery)
The Wattsonic hybrid inverter is a residential and light-commercial PV storage system that combines solar conversion and battery management in one unit. This ModbusCloud template connects to the wattsonic over Modbus TCP via the inverter's built-in LAN dongle at port 502. It reads battery power flow and state of charge, and exposes the on-grid discharge end SOC setpoint for remote control. With live battery power and SOC visible in your portal, you can track storage behavior, automate charge protection, and verify that the system responds correctly to grid conditions.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 3, read and write
- Brand
- Wattsonic
- Compatible models
- wattsonic
- Last updated
Registers (3)
2 read, 1 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| soc | % | Read | |||
| limitsoc | % | Write |
Loading registers…
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Use cases
- Monitor battery power in real time to verify the Wattsonic is charging from surplus PV and not drawing from the grid unexpectedly.
- Track state of charge over time to detect gradual capacity fade across seasons and flag batteries that no longer reach full charge.
- Alert on SOC dropping below a threshold during peak evening hours to catch inverter misconfiguration before it affects self-consumption.
- Write a higher discharge end SOC limit via the limitsoc register to protect the battery during EV charging periods.
- Compare daily battery power curves against PV production to confirm the Wattsonic operating mode is set correctly for the site.
Installation
Connect the Wattsonic LAN dongle to your local network and confirm the inverter is reachable by IP. No RS485 wiring is needed for TCP access; the dongle exposes Modbus TCP on port 502.
In the ModbusCloud portal, add your ModbusCloud Gateway to the same LAN segment as the Wattsonic inverter, then create a new device and import the Wattsonic (battery) template.
Set the unit ID to 255 and enter the inverter's local IP address and port 502 in the device connection settings. Save and activate the configuration.
Spot-check the soc register in the live data view and compare the reading against the Wattsonic app or display. If the value is zero or an error, verify the unit ID and that the LAN dongle is online.
Things to watch for
All registers return exception code 2 (illegal data address). What is wrong?
Wattsonic inverters require the polling address to be the documented address plus one. If the template address is 43000, the device expects 43001 to be queried. This is a known quirk of the Wattsonic register table. Check that the template addresses in your portal match the OpenEMS offsets, which already account for this shift.
The gateway connects but battery SOC reads zero even though the battery is charged.
Confirm the LAN dongle is fully initialised and the inverter is not in standby or night mode, which can suppress some register responses. Also verify unit ID is set to 255. If using Wi-Fi instead of a wired LAN dongle, switch to a wired connection as the Wi-Fi interface is known to produce intermittent timeouts and read errors.
I wrote to the limitsoc register but nothing changed on the inverter.
Register 52503 accepts values from 100 to 900, representing 10 to 90 percent. Writing outside this range is silently ignored. Also note that Modbus writes to the Wattsonic are not immediately reflected in the Wattsonic cloud app; the change takes effect on the inverter itself but may not propagate back to the cloud interface.
Is it safe to write to the limitsoc register frequently from an automation?
Use caution. Register 52503 controls the on-grid battery discharge end SOC, which governs how deeply the battery can discharge. Writing incorrect values can prevent the battery from discharging at all or push it below manufacturer-recommended depth of discharge, potentially accelerating degradation. Always write values within the 100 to 900 range and test changes during commissioning before enabling automated writes.
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