I solo'd him. What I did was I send T7 in to tank the emperor while I took out the clones. I popped saber ward followed by Call on the Force right away. Then I ran back to the room with the spiral ramp. When the emperor caught up to me, I pushed him off the edge. He would reset to the throne room, summon clones, but always come running back. I just kept pushing him right off. Eventually, after about 3 pushes or so, it killed him. It's the only way to kill an Emperor in Star Wars, it seems.