This is the place in which you can be placed of any faults (non conformities with a normal behaviour) during your life in the prison.
Solitary contains one bed and one Camera.
Reasons that you can be placed here: trying to break out of the prison (for example, a hole in any wall or floor of the prison or in the vent), stolen a Key from a Guard.
While you're in Solitary, you'll skip three days and all of your skills will be decreased by 10.
All Contraband items that you've placed in the prison will be confiscated.