What do you do when the wind isn’t blowing or the sun isn’t shining? Or, you live in a boring place where those things rarely happen.

There are already grid-scale (and home) storage solutions that solve this, but also redox flow battery tech is moving along fairly quickly, and those could potentially be made using relatively common metals unlike other battery types (like lithium). This video gives a good overview of how they work.

Regarding nuclear, I think micro-nuclear power could be useful and should be looked into, but with large scale nuclear plants, start-up costs and time are prohibitively high vs solar and wind. Most people aren't aware that nuclear projects often take 10-20 years before they're up and running, and we just don't have that kind of time. They also wouldn't fit very well with the decentralized smart grids that would be more ideal for solar and wind. Unless we can somehow magically solve these problems very quickly, nuclear just seems like a much worse option compared to the alternatives, and even China has been moving away from nuclear and more towards wind and solar.