The power register always reads zero even during daylight. Why?

The inverter may be in standby or waiting mode rather than actively feeding the grid. The DT/SDT protocol uses a status register at address 782 where 0 means pause or waiting, 1 means working, and 2 means error. Confirm the inverter is in working state before diagnosing the Modbus connection.

The Gateway connects but no register values appear in the portal.

The default unit ID on GoodWe SDT/DT inverters is 247. If the unit ID in the portal does not match the inverter setting, all reads will time out silently. Verify the ID via the SolarGo app or inverter display, then update the unit ID field in the ModbusCloud portal accordingly.

Energy values look implausibly large or jump erratically. What is wrong?

The energy register (address 786) is the high word of a 32-bit uint32 spanning registers 786 and 787. If only the high word is polled in isolation, the value will appear to contain fractional or inflated data. The template reads both words as a single uint32, so ensure no partial override has been applied to the register definition.

RS485 communication drops intermittently when multiple inverters share the bus.

GoodWe RS485 buses require a 120-ohm termination resistor on the last device in the chain. If the termination dip switch under the RS485 connector of the final inverter is not set to ON, reflections on the line cause intermittent read errors. Also keep total bus cable length within the RS485 specification and avoid unshielded cable near AC wiring.

Free Modbus template: GoodWe SDT/DT Inverter (pv)

The GoodWe SDT/DT Inverter is a three-phase, grid-tied PV inverter designed for residential and commercial solar installations. This ModbusCloud template connects to the GoodWe SDT/DT over Modbus RTU via the RS485 port, reading instantaneous AC output power and cumulative energy yield. With these two registers in the ModbusCloud portal, installers and building owners can track live PV production and lifetime energy totals without relying on the GoodWe SEMS cloud. The result is local, EU-hosted performance data that survives internet outages.

Name	Address	Function	Type	Unit	Access
power Instantaneous AC output power of the PV inverter, in watts.	781	FC03	uint16		R
energy Cumulative total AC energy generated since installation, 32-bit value.	786	FC03	uint32		R