Solarpunk is what you’re looking for. There’s not a ton of solarpunk books, but they exist, and they have that Star Trek style sense of wonder and exploration, with acknowledgement that not everything’s fixed and that they had to go through an apocalypse to get there

If you haven’t yet, read/watch The Magicians. Not quite the same plot, but >!they become kings and queens of their own narnia at some point. No one is particularly happy about this and they run into a lot of pushback “Strange women lying in ponds distributing swords is no basis for a system of government…” style !<