The solar panel on the -Y side of the spacecraft is fully deployed, but 20.5 degrees out of position. What happened is that a damper shaft in the solar array's deployment mechanism broke shortly after launch. Data form the spacecraft indicates that this event occurred 43 seconds after the array began unfolding from its launch-stowed configuration into its flight deployed configuration. This damper is a device that was installed to minimize the mechanical shock of deployment by slowing the motion of the array during deployment. The flight team theorizes that the broken shaft caused the damper arm to wedge into the hinge joint connecting the solar panel to the spacecraft.
Efforts are underway to determine the best method to free the damper arm from the hinge joint.
However, the -Y solar panel is currently generating full power, and the 20.5 degree position discrepancy does not pose a significant threat to the success of the mission.