Output connected to grid

First, check whether the output port is actually tied to a live utility grid. If it is, disconnect it from the grid. If that cause is ruled out and the fault does not clear, contact Sungrow Customer Service. The manual lists code 323 apart from the neighbouring generic System Fault codes. Those are cleared by turning the AC and DC switches off and back on to restart the inverter, but 323 has its own wiring check.