There are always unknown unknowns that might be correlated, like that flaw in the component. Weather systems like a https://en.wikipedia.org/wiki/Dunkelflaute are known facts. The good thing is that we do have excellent weather data for the last 75 years, so it is totally feasible for proponents of renewables to run their models through that historical data and say: Look, if we have that amount of renewables and that amount of batteries that would have been enough for the last 3 quarters of a century.

That would be go a very long way to convince me.