Yes, SOLARIZING is a Scrabble word!

Letter values in Scrabble US: S 1, O 1, L 1, A 1, R 1, I 1, Z 10, I 1, N 1, G 2.

Is it a valid word?

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

reverse some of the tones of (a negative or print) and introduce pronounced outlines of highlights, by exposing it briefly to light, then washing and redeveloping it
become overexposed
overexpose to sunlight
expose to the rays of the sun or affect by exposure to the sun