Yes, SOLITON is a Scrabble word!

Letter values in Scrabble US: S 1, O 1, L 1, I 1, T 1, O 1, N 1.

Is it a valid word?

SOLITON is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(physics) a quantum of energy or quasiparticle that can be propagated as a traveling wave in nonlinear systems and is neither preceded nor followed by another such disturbance; does not obey the superposition principle and does not dissipate

Also: soliton wave, solitary wave.