@Star12Mt Looks like you’ve collected a lot of great suggestions. For Becky Chambers, I’d recommend her novella To Be Taught, If Fortunate. It’s my favorite of her works, very sci-fi (scientists exploring life on another planet), and deeply hopeful, though not specifically solarpunk like Monk and Robot. Her first series (Wayfarers) is also hopeful space sci-fi.
For Kim Stanley Robinson, my favorite of his works is the Mars Trilogy. Like all of his work it can be a long slog, heavy worldbuilding, pages and pages of geology, etc. But all of it’s good, like an epic story wrapped up in a fascinating nature documentary, all imagining a better future.
Another one I'd add, that’s very sci-fi and also very solarpunk, is Jayan F.R.’s novel The Wind of Venus (set in a community of airships floating around Venus). It’s a wholesome coming of age story for the first half, then there’s more action the second half. I gather it’s book one of a forthcoming series.
I also strongly second Ruthanna Emrys’ A Half Built Garden, hopeful sci-fi first-contact story, and very solarpunk. Susan Kaye Quinn’s Nothing is Promised series is a great read too, more near-future climate tech intrigue on Earth.