Adele swept the board at the annual show, scooping the top award for 25.
Beyonce had previously also lost out to Taylor Swift and Beck in the cateogry.
In since deleted posts, Solange tweeted on Monday: "There have only been two black winners in the last 20 years for album of the year. There have been over 200 black artist who have performed.
“Create your own committees, build your own institutions, give your friends awards, award yourself, and be the gold you wanna hold my g’s."
Solange had previously tweeted a link to Frank Ocean's reason for boycotting the awards.