Even overnight storage is expensive.

But yes, it needs to work in both the summer and the winter, so anything not at the equator is going to have seasonal challenges. I'm excited about a lot of innovating battery proposals, such as stacking heavy boxes and hydrogen generation, but none of those are anywhere near capable of production scale. The massive gorilla in the room is using EV batteries during the night and recharging them during the day (the car would reserve enough for your morning commute), but that's largely theoretical and charging infrastructure is far from sufficient to make that work at scale (not to mention I don't think there are enough EVs). We have trouble making enough batteries to keep up with EV demand, so there's no hope of using conventional batteries to actually transition a large countries anytime soon.

So until we solve those problems, we need an energy backbone. Nuclear is a great option, especially if we can destigmatize it so construction can be cheaper. I live in an area that would be perfect for it (Utah USA, just stick it in the desert on the other side of the mountains), yet people keep blocking every proposal out of FUD. So a lot of our energy comes from coal and gas, and we sell a our excess to California, which is utterly stupid since we have geography that collects pollution and makes the air unhealthy to breathe.