Ecotopia is a fun one because it hits all the notes but predates the genre.

Murder in the Tool Library is a favorite of mine because the setting is awesome and aspirational while feeling real and human, and because the murder mystery plot is a change from the usual ecofiction.

The solarpunk TTRPG Fully Automated! is free (libre and gratis) and has several sections devoted to its setting and worldbuilding that helped me understand a bunch of solarpunk concepts by seeing them in practice and to start thinking much bigger with my own fiction. It also has some good advice on creating engaging plots in an aspirational solarpunk setting where a lot of the usual problems have been solved.