Sunway wattsonic (grid)
The Sunway wattsonic is a three-phase hybrid solar inverter sold under the Sunway brand, deployed in residential and light-commercial PV-plus-storage installations. This template reads the inverter's built-in grid meter over Modbus TCP, capturing total grid power at address 11000 and per-phase active power across phases A, B, and C at addresses 10994 to 10998. Phase currents for all three phases are read from addresses 11010 to 11014. Positive values indicate grid import; negative values indicate export. Connecting the wattsonic to ModbusCloud Gateway gives installers continuous visibility into grid exchange balance and per-phase load asymmetry without additional metering hardware.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 7, read only
- Brand
- Sunway
- Compatible models
- wattsonic
- Last updated
Registers (7)
7 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| currents_a | A | Read | |||
| currents_b | A | Read | |||
| currents_c | A | Read | |||
| powers_a | W | Read | |||
| powers_b | W | Read | |||
| powers_c | W | Read |
Loading registers…
Send your device list
If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor total grid power in real time to verify that PV and battery cover the site load.
- Track per-phase active power on phases A, B, and C to detect load imbalances across the installation.
- Alert on sustained grid import above a threshold to identify unexpected consumption or inverter faults.
- Compare phase currents over time to spot wiring asymmetries or tripped circuit breakers on a specific phase.
- Report daily grid import and export trends to building owners for energy-cost analysis and tariff optimisation.
Installation
Enable Modbus TCP on the wattsonic inverter by ensuring the LAN dongle is connected and active; the inverter is reachable on port 502 with unit ID 255 by default on the local network.
Connect the LAN dongle's RJ45 port to the same network switch or LAN segment as the ModbusCloud Gateway so both devices share IP reachability.
In the ModbusCloud portal, add a new device, select the Sunway wattsonic (grid) template, and enter the inverter's local IP address, port 502, and unit ID 255.
Spot-check the connection by verifying that register 11000 returns a plausible signed watt value matching current grid conditions; phase power registers 10994 to 10998 should sum close to the total.
Things to watch for
All registers return zero or an illegal-address error. Why?
The wattsonic firmware requires the polled address to be the documented address plus one when accessed over TCP. If you have manually configured register addresses, verify each address is offset by plus one from the value shown in third-party documentation. The addresses in this template already account for the correct offset as implemented by OpenEMS.
The gateway connects but no values appear after import. What now?
Confirm the LAN dongle is active and its LED shows a network link. Check that unit ID is set to 255 in the portal device settings. If the inverter is on a different VLAN or behind a firewall rule, port 502 TCP must be open. Try pinging the inverter IP from a device on the same segment to rule out routing issues.
Phase current values look ten times too large. What is the scaling?
Registers 11010, 11012, and 11014 return current as uint16 values in tenths of an ampere, so a raw value of 153 represents 15.3 A. Ensure your portal channel applies a scale factor of 0.1 to these three registers. The total power register at 11000 is in whole watts and requires no scaling.
Per-phase powers do not sum to the total power reading. Is this normal?
Minor discrepancies between the sum of per-phase powers at 10994 to 10998 and the total at 11000 can occur because both sets are read in separate Modbus transactions. Short-lived load transients between polls cause the mismatch. If the gap is consistently large, check for firmware updates on the wattsonic inverter through the Wattsonic app.
Want to see how it works?
