You build electrolyzers and batteries?
* Battery storage is minutes of electric output
Cold snaps and inversions (clouds are low, no wind, cold) are counted in days to weeks.
New solar parks often come with a couple of hours of battery storage. You numbers seem to be out of date.
You're mixing up the use of batteries for grid stabilization with their use for storage.
But it might come as a shock to you, cities are taking in order of MW to GW
A typical grid-storage battery will have enough storage to dispatch power at 100% of its rated capacity for 4 hours.
Of course if you draw out the energy at less than full capacity, it will take longer to fully discharge.
The largest battery currently in the US - Moss Landing - for example is rated 750 MW/3,000 MWh - which means it can sustain 750MW of output for 4 hours and it does this daily.
This is not "20 minutes".