I don't know a lot of solarpunk. The most would be star trek, and it works by focusing on exploration.
Fantasy works well IMO because it features a broad diversity of scenarios and possibilities. Monsters can be akin to natural threat or opposing factions. You can work an utopian city or a distopian one. It's familiar because it's culturaly rooted for centuries.
To get the equivalent, you would need a universe where solarpunk lives with cyberpunk and many other kinds of futures. Which is kind of what star trek does: by focusing on exploring the fringes of the federation, they get to meet independent planets and hostile empires that will fuel the stories. Andromeda works quite a bit like that btw.
So my point here is first that by focusing on the solarpunk aspect I feel like you make it harder start a story. The document should have something to start the stories, so an imperfect society or one that is a beacon of hope in the galaxy for example.
And the second is the exploration aspect will be very important for that. Both for investigation and exploring. But reading more, it's actually grounded, no space exploration. So it's oriented toward investigation. But there are no specific rules for that either.
There is an odd thing too: how do you justify characters with combat training in an utopian solarpunk society? I guess the organisation would provide the formation.
I am personally not found of the setting being rooted in the US and limited to the solar system, but that's a matter of taste. Likewise the 2d10 roll bellow and the classless system. But it seems to work. I like the medium crunch but the card system is new to me, it's interesting.
Something to consider is a tie between the mechanics and the universe. For example in dnd you have the alignment and the planes. In cyberpunk you have the humanity versus the augments. These do a lot to build an identity. For solarpunk, maybe it could be that dying is easy but reviving is also. There could be a corruption similar to alignment that would reflect how progressive vs capitalistic/selfish a character is. Something for your system to be less "generic with some solarpunk lore dump". Something that would make the system mechanically solarpunk.