Well, the split is probably related to how solarpunk isn't really related to the punk movement. Cyberpunk art usually describes dystopian environments, and the way individuals and communities adapt to is and subvert it.
On the other hand, solarpunk art is an overtly optimistic movement, which leaves very little room for a confrontational political message. The example tweet you cited is pretty, with a "just add trees" city, where the necessary trappings of a vertical city (mass transportation, crowds, pollution, etc) are absent.
This sounds a bit critical of the solarpunk movement, but it's honestly hard for me to reconcile the hard problems I face and what I see in this movement. Merely adding the "punk" affix is not going to transform what would probably better be called solar-hippie.
On the other hand, solarpunk art is an overtly optimistic movement, which leaves very little room for a confrontational political message. The example tweet you cited is pretty, with a "just add trees" city, where the necessary trappings of a vertical city (mass transportation, crowds, pollution, etc) are absent.
This sounds a bit critical of the solarpunk movement, but it's honestly hard for me to reconcile the hard problems I face and what I see in this movement. Merely adding the "punk" affix is not going to transform what would probably better be called solar-hippie.