Electric Utilities worldwide are experiencing problems with system management with large PV systems being added to their generation mix.
In Australia Nine more solar farms could have output cut to zero due to system strength issues
Earlier in Australia AEMO slashes output of five big solar farms by half due to voltage issues
The above articles reference additional similar problems.
In Arizona TEP has identified areas in there service territory that are already saturated with PV systems TEP PV Saturation Maps