GoodWe ES Series Overview

GoodWe ES series (3-5 kW hybrid single-phase) includes a Modbus TCP server accessible on port 502 with unit ID 247 (hexadecimal 0xF7). This non-standard unit ID is the most common cause of failed integrations — the default unit ID 1 used by many gateways will silently fail to read any registers.

Key Modbus Registers

Important registers for GoodWe ES: 35103 (Vpv1, uint16, 0.1V), 35109 (Ppv total DC, int16, W), 36005 (E_Day, uint16, 0.1 kWh), 36069 (battery SOC, uint16, %), 36021 (battery power, int16, W, positive=charge), 36025 (total active power export, int16, W).

GoodWe Sensorbox

The optional GoodWe Sensorbox accessory mounts CT clamps on grid cables and adds register 36007 (grid power, int16, W, positive=import). Without the Sensorbox, grid import/export data is unavailable via Modbus — the inverter only knows its own DC input and AC output.

KNX Integration with MDT Modbus Gateway

MDT Modbus gateway polls key registers every 10 seconds. Map battery SOC (register 36069) to KNX DPT 5.001 (percentage, 0-100%). Map battery power (int16, signed) to DPT 9.001. For display on KNX visualisation panels, map E_Day to DPT 14.073 (energy in kWh, multiply raw value by 0.1).

Self-Consumption Logic in KNX

Create a KNX logic block comparing grid power (register 36025) to a threshold. If grid export exceeds 500W continuously for 120 seconds, send an ON telegram to the actuator controlling the immersion heater or pool pump. Use a KNX timer block for the 120-second delay to avoid false triggers from momentary PV fluctuations.

SG Ready Battery Charging

GoodWe ES has no native SG Ready input on the inverter terminal block. Instead, use a KNX dry-contact output module (MDT AKD-0800.01) to close a relay connected to GoodWe's external signal input (AC coupling signal input terminal, see GoodWe ES installation manual section 6.3). This triggers forced battery charge from grid when grid tariff is low.

Work Mode Monitoring

KNX monitoring of GoodWe work mode via register 36074: 0=wait, 1=normal, 2=charge, 4=backup, 8=fault. Map to KNX DPT 5.001 and display as a status indicator in the building visualisation. When value equals 8 (fault), trigger a KNX alarm notification.

Troubleshooting Unit ID

Unit ID 247 is correct for GoodWe; some third-party Modbus gateways default to unit ID 1 and fail silently — always verify communication with a standalone Modbus Poll tool on a laptop connected to the same LAN before wiring the KNX gateway permanently. A successful read of register 35109 returning a plausible watt value confirms correct configuration.