Batteries (or pumped storage hydro, which is more like a gravity-driven capacitor)
But yeah batteries would be nice.
It's a meaningful contribution I would have thought.
[0] https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power...
Starting this year, in Romania you cannot put new PV capacity online without the storage for it, is mandatory. Possibly for existing ones, but I am not sure.