Sunway wattsonic (pv)
The Sunway wattsonic is a hybrid PV inverter that converts DC output from rooftop solar arrays into AC power for residential and commercial use. This ModbusCloud template reads the device over Modbus TCP using the inverter's built-in LAN dongle on port 502. The single monitored register is the real-time PV generation power at holding address 11028, giving installers and asset managers a live watts figure directly in the portal without additional hardware. Even a single power reading enables yield tracking, alert configuration, and integration into multi-site energy dashboards.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 1, read only
- Brand
- Sunway
- Compatible models
- wattsonic
- Last updated
Registers (1)
1 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read |
Loading registers…
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Use cases
- Monitor real-time PV generation power to verify the installation is producing as expected on clear days.
- Alert on a drop in PV power below a threshold to detect soiling, shading, or inverter faults quickly.
- Track daily PV output over time to compare seasonal yield and spot long-term performance degradation.
- Compare PV power readings against irradiance data to verify inverter conversion efficiency on site.
- Report live generation figures to building owners or facility managers via the ModbusCloud portal dashboard.
Installation
Connect the wattsonic inverter's LAN dongle to the same local network as the ModbusCloud Gateway, and confirm the inverter has a stable IP address on port 502.
In the ModbusCloud portal, add a new device, import the Sunway wattsonic (pv) template, and set the unit ID to 255 as used by the inverter's built-in Modbus TCP server.
Assign the gateway to the device entry in the portal, enter the inverter's local IP address and port 502 under the communication or Modbus section, then save.
Trigger a manual poll in the portal and verify that register 11028 returns a non-zero watt value during daylight hours to confirm connectivity.
Things to watch for
Why does register 11028 always return zero at night?
This is expected behaviour. The wattsonic reports zero PV generation when no solar input is present. Verify the reading is non-zero during daylight. If it remains zero in full sun, check that the unit ID is set to 255 and the correct inverter IP is configured in the portal.
The gateway connects but no values appear in the portal. What now?
Confirm the inverter's LAN dongle is active and the inverter is reachable on port 502 from the gateway's network segment. Some firmware versions require the Modbus TCP server to be explicitly enabled under the inverter's communication or network settings. Check that the local firewall is not blocking port 502.
Register addresses from the official documentation do not match what works. Why?
The wattsonic register table uses zero-based addresses internally, but the Modbus TCP server applies a +1 offset. The address 11028 in this template already accounts for this offset. Do not subtract 1 when configuring the gateway: use 11028 as-is.
The PV power value looks correct sometimes but shows errors intermittently. What causes this?
The wattsonic LAN dongle can produce read timeouts under continuous polling. Community users report that adding a 100 ms inter-request delay reduces errors significantly. Also confirm only one Modbus TCP client is polling at a time, as the dongle supports a limited number of concurrent connections.
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