solo collection？

Good q, Nancy. Afraid my search not too successful but you might have better luck on Google

http://onelook.com/?w=solo+collection&ls=a

I suspect it means a collection of works by a single designer, composer, or performer

A "solo collection" is one in which all items were designed by the same person, and is to be distinguished from a "joint collection" which has items designed by more than one person.