This clicking noise occurs when determining the grid impedance measurement; you need not worry about this in any way.
When determining grid impedance, the inverters give a cyclical current pulse to the connected grid. This pulse is audible. Grid impedance refers to the alternating current resistance of the power distribution grid.
The volume of the current pulse varies according to the power being fed into the grid. The device type and hardware components being used (e.g. chokes) are also important. To keep the volume as low as possible, we recommend installing the inverter against solid walls. Noise emissions may be increased by plasterboard and wooden walls.
Background: According to standard DIN VDE 0126-1-1, all devices that feed into the power distribution grid must be able to detect an outage of the power distribution grid and consequently perform an all-pole disconnection from the grid. This increases the safety of persons. In addition, the supply grid operator can perform maintenance work on the grid without any danger from devices feeding in.
To detect an outage of the power distribution grid, a different procedure that has been allowed in Germany from 2006 is now used with our inverters. The essential advantage is that this procedure works silently.
However, retrofitting the impedance measurement for stock inverters to the currently used procedure is not possible due to hardware requirements.
This applies for all Sunny Boy and Sunny Mini Central inverters.