I was digging up old layers of the Internet and found out about old (well, late 90s, early 2000s) texts by Bruce Sterling who mentioned his Viridian notes where he describes something very close to a solarpunk movement (sustainability focused tech and social changes). It is fun to read because some have very strong cyberpunkish vibes but with the twist that cyberpunk describes the world we are in right now and viridian is the world we want.
It led me to learn that there is a label that more or less matches solarpunk in political theory: Bright Green Environmentalism
This is a huge corpus of text and I obviously disagree with some things, and the 1999 vibes of promoting at the same time intense air travel (for multi-culturalism) and sustainability sounds a bit tone-deaf, but I find it interesting to dive in with a tolerant curiosity.
(Dig that 1999 GIF btw!)
Obviously you can't describe that in detail in a manifesto, but it makes it clear that anything not anti-authoritarian can not be called Solarpunk without completely perverting the idea. That is a form of protection against co-optation of ideas.