On the build side, this is fantastic. I always love the use of those bootleg hands, and the color scheme is appealing to me. However, I will say that your explanation of why he has no weapon lind of shows a bit of a misunderstanding of how toa powers work (this is me nitpicking, it doesn’t really matter as long as the MOC looks great). Toa don’t carry a weapon as a tool of force, since it is against the Toa code of honor to kill. Instead, they use them to channel their elemental power ig. Kopaka uses his sword to freeze things, Lewa Nuva uses his swords to glide, etc.) So either Solaris just breaks the rules and kills anyway, or he has completely mastered his elemental powers, something I find unlikely, seeing as you said he has absorbed so much radiation that he has become infused with its power.
Anyway, nice moc lol