
The Wattsonic WTS 3-Phase is a hybrid solar inverter series available in six models from 6 kW to 20 kW (WTS-4P-3P, WTS-5KW-3P, WTS-6KW-3P, WTS-8KW-3P, WTS-10KW-3P, WTS-12KW-3P). It supports dual MPPT PV inputs, lithium battery storage, on-grid and off-grid operation, and three-phase backup output. TapHome communicates with the inverter via Modbus RTU over RS-485 through the EMS port on the Multi-COM connector.
The TapHome template provides comprehensive monitoring of PV generation, battery state, grid power flow, and per-phase measurements, along with control of running modes, charge/discharge time windows, SOC protection, grid export limits, and off-grid settings.
Hardware connection
Wiring overview

The inverter has all communication ports in the Multi-COM connector (COM2) at the bottom of the unit. There are two RJ45 ports (Meter and BMS) and a 20-pin terminal block for EMS, DRED, relay, emergency stop, and CAN parallel connections.
RS-485 EMS connection

Connect TapHome to the EMS RS-485 pins on the Multi-COM terminal block:
| Multi-COM Pin | Definition | TapHome Connection |
|---|---|---|
| 13 | 485 B1 | B-/D- on TapHome RS-485 |
| 14 | 485 A1 | A+/D+ on TapHome RS-485 |

The Multi-COM connector uses a waterproof cable gland assembly. Wire diameter must be 4–6.5 mm, cross-sectional area 0.5–1.5 mm². Strip the outer insulation to 55 mm and inner wire insulation to 8 mm. Tighten terminal screws to 1.2 +/- 0.1 Nm.
Terminating resistor
A built-in RS-485 terminating resistor for the EMS bus is available on the communication port block (visible in the connector diagram above). Enable it only on the last device on the bus. TapHome Core has its own built-in 120 Ohm terminating resistor on BUS terminals.
Configuration
Communication parameters
The Modbus RTU connection uses the following fixed parameters:
| Parameter | Value |
|---|---|
| Baud rate | 9600 |
| Data bits | 8 |
| Parity | None |
| Stop bits | 1 |
| Slave address | 1–247 (default 1) |
| Byte order | Big-endian |
Enabling Modbus communication
The EMS RS-485 port is enabled by default on the Wattsonic WTS 3-Phase inverters. No additional configuration in the inverter menu or app is required to activate Modbus RTU communication. Simply connect the RS-485 wires to pins 13 and 14 on the Multi-COM connector and configure the correct Slave ID in TapHome.
The default Slave ID is 1. If multiple inverters are on the same RS-485 bus, each must have a unique Slave ID. The Slave ID can be configured through the Wattsonic monitoring app or the inverter display panel.
Device capabilities
Running mode and system control
The template provides full control over the inverter operating mode through the Running Mode Setting service action with four modes:
- General Mode — PV power supplies loads first, then charges the battery, then exports to grid
- Economic Mode — time-of-use optimization configured through charge/discharge time windows
- UPS Mode — priority to battery backup for critical loads
- Off-Grid Mode — standalone operation without grid connection
The current Running Mode is displayed as a module-level service attribute. The Inverter Running Status service attribute shows the real-time state: Wait (waiting for grid), Check/Self-test, On Grid, Fault, Flash/Firmware update, or Off Grid.
Additional system control switches:
- Off-Grid Running Switch — enables or disables off-grid (backup) operation
- Asymmetric Output Switch — enables asymmetric power output across phases for zero-injection mode
- Peak Load Shift Switch — enables battery charging during off-peak hours and discharging during peak hours
Battery management
Battery SOC displays the state of charge as a percentage (0–100%) with eight service attributes providing detailed battery monitoring:
- Battery Health (SOH) — state of health as percentage
- Battery Voltage and Battery Current — real-time DC measurements
- Battery Power — instantaneous charge/discharge power in kW
- Battery Charge/Discharge Energy Today — daily energy counters in kWh
- Total Energy Charged/Discharged — cumulative lifetime energy counters in kWh
Battery State indicates the current charge/discharge direction (Charging or Discharging).
Battery protection is configurable through:
- On-Grid SOC Protection — enables SOC-based discharge cutoff while grid-connected
- Off-Grid SOC Protection — enables SOC-based discharge cutoff in off-grid mode
- Off-Grid Battery DOD Setting — configurable depth of discharge limit (0–100%) for off-grid mode
Charge and discharge scheduling
The module exposes Charge Start Time, Charge Stop Time, Discharge Start Time, and Discharge Stop Time as both readable service attributes and writable service actions. Each time value uses hour/minute encoding. The Charge Start Time service action accepts Hours (0–23) and Minutes (0–59) parameters.
These time windows work with Economic Mode to optimize battery usage around electricity tariff schedules.
Per-phase power monitoring
Three electricity meter devices (Phase A Power, Phase B Power, Phase C Power) provide per-phase active power from the external meter in kW. Each phase includes nine service attributes:
- Backup Voltage, Backup Current, Backup Frequency, Backup Power — measurements on the backup output port
- Inverter Power — active power on the inverter grid port
- Grid Phase Voltage and Grid Phase Current — grid-side measurements
- Grid Line-to-Line Voltages — two line voltage readings per phase (e.g., A/B and C/A for Phase A)
PV generation monitoring
Two electricity meter devices monitor the dual MPPT inputs:
- PV1 & Total PV Generation — PV string 1 instantaneous power (kW) and cumulative total PV generation from installation (kWh), with service attributes for PV1 current, PV1 voltage, total PV generation time, and total backup port energy
- PV2 & Total PV Generation — identical structure for PV string 2
Additional PV sensors:
- PV Generation Energy Today — daily PV energy production in kWh
- Total PV Generated Energy — cumulative lifetime PV generation in kWh
Grid monitoring and export control
Grid Frequency displays the grid frequency in Hz with four service attributes for cumulative grid energy totals:
- Total Energy Purchased from Grid (Inverter Side) and (Meter Side) — two measurement points for grid import energy
- Total Energy Injected to Grid — cumulative grid export energy
- Total Loading Consumed Energy — cumulative load consumption measured at grid side
Daily energy counters:
- Grid Injection Energy Today — daily grid export energy in kWh
- Grid Purchasing Energy Today — daily grid import energy in kWh
- Loading Energy Today — daily load consumption in kWh
- Backup Output Energy Today — daily backup port energy in kWh
Grid Export Power Limit Switch and Grid Export Power Limit (0–100%) enable limiting the power exported to the grid, useful for zero-injection or export limitation requirements.
Temperature monitoring
Four temperature sensors (Temperature Sensor 1 through 4) read internal inverter temperatures in degrees Celsius.
Total AC power
Total Inverter AC Power provides the sum of AC power across all three phases from the inverter in kW.
System diagnostics
The module ReadScript monitors two fault flag registers (H:10112, H:10113) and reports individual fault conditions including: Mains Lost, Grid Voltage/Frequency Fault, DCI Fault, ISO Over Limitation, GFCI Fault, PV Over Voltage, Bus Voltage Fault, Inverter Over Temperature, SPI/E2 Fault, AC Transducer Fault, Relay Check Fail, and Internal/External Fan Fault.
The Clear Over-load Protection Flag service action resets the overload protection lockout after an overload event has been resolved.
The Model Info service attribute identifies which of the six WTS models is connected, and Date and Time reads the inverter’s internal RTC clock.
Additional capabilities
The Wattsonic WTS 3-Phase inverters also expose registers for total 3-phase meter power, total 3-phase backup power, combined PV input power, BMS diagnostics (pack temperature, cell-level min/max voltage and temperature, charge/discharge current limits, status and error codes), off-grid output voltage and frequency settings, per-phase and total inverter power settings, on-grid battery DOD threshold, charge/discharge power limits, and firmware/hardware version information. These can be added in a future template update.
Troubleshooting
No Modbus communication
- Verify wiring: Pin 13 (485 B1) to B-/D- and Pin 14 (485 A1) to A+/D+ on TapHome. Swapped A/B wires are the most common connection issue.
- Confirm communication parameters in TapHome: 9600 baud, 8 data bits, no parity, 1 stop bit.
- Check the Slave ID matches between the inverter and TapHome configuration (default is 1).
- If using a long RS-485 cable, enable the terminating resistor on the last device.
- Check the Communication LED on the inverter front panel — green flashing indicates active RS485/CAN communication.
Inverter shows “Wait” status
The inverter enters Wait status when the grid is not detected or grid parameters are outside the configured regulation limits. This is normal during grid outages. The Inverter Running Status service attribute will show “Wait, wait for on grid” (value 0).
Cloud app and Modbus control conflicts
Changes made through the Wattsonic cloud app and Modbus local writes may not synchronize bidirectionally. When using TapHome for inverter control, avoid making conflicting changes through the cloud app simultaneously.
