[pprd]

There is a way to feed the energy you make using renewable sources into the grid so you can use them when they are around. Since you're still connected to the grid, conventional energy sources or better yet, renewable energy being generated elsewhere, can take over when the renewables aren't available.

[InclinedPlane]

Which is what I said.

The problem is still severe. In a country the size of the US it is still possible for there to be days of very little wind across the whole country. And, of course, once the Sun goes down on the West coast there won't be any power coming from solar for many hours. Which means that in a worst case scenario you need to rely on nuclear, coal, or hydrocarbon based power generation. And it means that you can't avoid having to build out conventional power generation capacity to match peak loads (which can occur when solar and wind power production is effectively zero).