Yes, SOLILOQUY is a Scrabble word!

Letter values in Scrabble US: S 1, O 1, L 1, I 1, L 1, O 1, Q 10, U 1, Y 4.

Is it a valid word?

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

speech you make to yourself
a (usually long) dramatic speech intended to give the illusion of unspoken reflections