And you have offered no refutation of that statement largely because you have no clue how the grid works.
If you have a large fraction of your grid supplied by renewables you need to have idle capacity built and standing by in case the renewable production drops suddenly. This idle capacity is a cost that must be paid for and it is not cheap. That is why there is pressure on Germany to subsidize natural gas plants to prevent them from shutting down because they can't sell enough electricity to make them viable on their own. Germany has recently changed their system to allow gas production to be given priority over wind and solar (i.e. wind and solar power is dumped) to make the economics better for the absolutely essential gas plants.
What you seem to be referring to as "idle capacity" is actually existing capacity. And yes the sun goes down and the wind doesn't always blow but renewables can feed into the existing grid so we can throttle back that coal burner for a good portion of the day.