Scientists in California have modeled a solar-heavy/wind power electricity grid, without nationwide HVDC, that could reliably deliver 80% of U.S. electricity needs. 100% of needs would require 3 weeks of energy storage.
— Read on pv-magazine-usa.com/2018/03/01/12-hours-energy-storage-80-percent-wind-solar/
or whatever you'd like, just please think…