@alxd i dont see why it couldnt use electronic instruments, as long as it's understood that the electricity is generated in a sustainable/regenerative way. in general i feel like harmonizing human technological progress with nature is the whole point of solarpunk, so i feel like it'd be fitting
as for albums i associate with the genre, it's purely a vibes-based association, but Plantasia by Mort Garson comes to mind: https://www.youtu.be/SZkR3PyHTs0