Understanding Hybrid Solar Inverters and Modbus RTU
Several manufacturers offer hybrid solar inverters with Modbus RTU (RS-485) communication, suitable for integration with battery storage systems and Building Management Systems (BMS), including Tridium Niagara N4.
Please look at LoRa Wireless RS485 transmitter and receiver with LCD screen – 2 Units
However, there is an important distinction between two types of communication:
- Inverter ↔ Battery BMS: Communication for battery state of charge (SOC), voltage, current, temperature, charge/discharge limits and protection. This often uses CAN bus rather than Modbus RTU.
- Inverter ↔ Building Management System: Communication using Modbus RTU over RS-485 for monitoring, alarms, operating modes and, where supported, control of battery charging and discharging.
If you need Modbus RTU communication directly between the inverter and battery, check the manufacturer’s supported battery communication protocol. An inverter having an RS-485 Modbus port does not automatically mean its battery interface uses Modbus RTU.
Manufacturers worth considering
| Manufacturer/range | Battery communication | External Modbus integration |
|---|---|---|
| Sunsynk hybrid inverters | CAN or RS-485, depending on battery | Model-specific RS-485 Modbus support |
| Deye hybrid inverters | CAN / RS-485, depending on battery | Model-specific Modbus RTU |
| Solis hybrid inverters | Usually CAN or RS-485, depending on battery | Modbus RTU on supported models/interfaces |
| GoodWe ET / ES series | Battery-specific CAN / RS-485 | Model-specific Modbus integration |
| Victron MultiPlus-II GX | Primarily CAN-based managed battery integration | Documented Modbus TCP through GX |
These are candidate ranges, not a guarantee that every model supports direct battery Modbus RTU.
Sunsynk specifically documents battery BMS communication over CAN or RS-485, with the required protocol and pinout depending on the battery model.
Victron offers particularly well-documented external monitoring and control using Modbus TCP, including battery and inverter registers.
The key requirement is protocol compatibility, not simply an RS-485 connector. Many hybrid inverters use proprietary RS-485 BMS protocols or CAN bus rather than standard Modbus RTU.
Suitable inverter and battery combinations
The following are supported combinations or documented RS-485 candidates, rather than proof of open, generic Modbus RTU interoperability.
| Hybrid inverter | Battery | Communication | Status |
|---|---|---|---|
| Deye SUN-5K-SG04LP1-EU | Wattsonic Li-LV series | RS-485, protocol setting 14 | Listed by Deye |
| Deye SUN-5K-SG04LP1-EU | Pylontech US5000 | RS-485, protocol setting 12 | Listed by Deye |
| Sunsynk 5 kW SG04LP1 | Manufacturer-approved lithium battery | CAN or RS-485, battery-dependent | Compatibility list required |
Deye’s published approved-battery lists cover the SG04LP1-EU family and identify RS-485 battery options and configuration numbers.
Sunsynk confirms that the inverter must be configured with the correct battery protocol and communication cable pinout.
Please look at LoRa Wireless RS485 transmitter and receiver with LCD screen – 2 Units
