From a recent site
55%
output on a 17 MWp solar site that could have run at 100%
The plant was doing exactly what it was told. It was told the wrong thing.
The power plant controller miscalculated its set point and held the site back. No alarm was raised, and on screen the plant looked healthy. The set point the grid sent, the set point applied and the available power were all being recorded. Nobody was comparing them.
Catching it means comparing the three values the site was already recording: the set point the grid sent, the set point applied, and the available power.