Thing is, there's no space in the exotic weapons kiosk for them. There's only 5 spaces for heavy weapons (thunderlord, truth, and 3 swords). The right side special weapons is where Black Spindle and SS go, and the top right is the gunsmith class exclusive exotics. If solar and void versions do exist, they will probably be element swap options in thunderlord just like the dark below fusion rifle that could be solar or arc. How to unlock that I dont know.