Replace main panel or use subpanel?
Here is my setup and what i would like to do. I have a Sqare D QO12L200RB main lug panel as the main disconnet panel for my house. In it there is one 90 amp breaker that feeds the main panel inside my house and the other slots are taken up with the main 220v circuits for the house (A/C, Hot Water heater, Elect. Range, etc.) I would like to run a line to my shed but have no room left in the panel. Is a subpanel the way to go?? Actually, I would prefer to replace the main lug panel with a main breaker, so I have a way to shut it off. Would it be better to do this instead of installing a subpanel?
Thanks in advance for your help!