The Solais system was an inhabited planetary system that was located in the Alpha or Beta Quadrant. There were at least five planets in this system, including Solais V, which was the homeworld for the humanoid Solari.
In 2365, the Federation starship USS Enterprise-D ferried a mediator to Solais V. He was there to negotiate a peace to a centuries long planetary conflict. (TNG: "Loud As A Whisper")
In 2371, the SS Xhosa ferried cargo to Solais V. (DS9: "The Adversary")