I soloed the Esseles Flash point with my lvl 25 smuggler and companion. It was easy since I wasn't taking any damage. I'm guessing it can be soloed at a lower level char, but not sure where that point is. I was NOT able to solo Esseles with my lvl 12 trooper and companion. I could not take out the Iron boss. Which is interesting as it's listed as a 2 player group for my trooper and listed as a 2+ player group for my smuggler. I did try to solo Esseles with my smuggler at an earlier level (like 12 or 13) and could not defeat the Iron boss either. Both times I didn't have the best armor/fire power, stims, or fighting strategies in place.