Sci Fi and Fantasy stories very rarely fall just into those labels for categories. Really, they're usually descriptions of a setting -- there's such a thing as a sci fi story that's really all sci fi and nothing else, and I think there's probably such a thing as a fantasy novel that's just fantasy. But that's not common. What happens more often is subgenres of SF/F become the setting-side of a descriptor, where another genre label becomes the plot-side.
For example, steampunk is mostly adventure novels. Urban Fantasy is mostly pulp detective fiction, and in a closely related boat paranormal romance is sort of Urban-Fantasy-Shelved-Elsewhere.
I'm not sure that's even true of the actual majority of the works in these genres. But they are definitely recognizable by their correspondence.
So -- what's the corresponding genre to Solarpunk?
Is it back to pure SF? Speculating on new technologies and running through their implications?
Is it a techno version of Urban Fantasy?
Is it adventure?
I have no idea.
I have seven Wikipedia pages open right now, and I'm going to start putting together a brainstorming document. I am eagerly open to input from anybody else who's looking to start writing Solarpunk. What kind of story captures the spirit of this milieu?