I'm a fan of the YouTuber "andrewism", who regularly makes videos on an anarchist solar punk society. I don't think he supports solar punk just as an aesthetic, but believes it's legitimately part of what an ideal and egalitarian society would look like, alongside other concepts he's discussed like library economies.
I don't think solar punk is idealist either. Idealism doesn't just mean it's still just a concept, or that people want to use it as a goal. Solar punk is materialist because it describes a society that reproduces the values that sustain it, like land stewardship and collectivism. It describes a super structure with communal control of resources, which then does the whole self reinforcement with the base (which, admittedly, solarpunk also describes). It's not just the aesthetic.