The missing piece for me in any renewable puzzle is evidence. At a grid level (either state or national) has anyone actually figured out how much storage we nee

The missing piece for me in any renewable puzzle is evidence. At a grid level (either state or national) has anyone actually figured out how much storage we need? Based on say a P90 worst case, what % of power is down, for how long, and how much storage do we need to manage that? Or any such similar study. Traditional power gen is much easier. Plonk it down and essentially it works (with various stabilisation mechanisms in place). Renewables however take a lot more planning.