Inverters are the problem. They're closed source and power engineers cant test their fault behavior well.

(One of ) the problem with inverter the angular velocity of a spinning rotor is trivially easy to define and measure. The operating frequency of the grid that an inverter needs to target is hard to define under the realtime constraints of a failing grid.

Which is what brought Spain down. It wasnt the panels and windmills, it was the inverters.