This study examines the reliability of k-out-of-n: F balanced systems incorporating common bus performance sharing. The system comprises m sectors, with each sector containing n components. Each component has multiple performance levels to fulfill random demands. All components are interconnected through a common bus, enabling the surplus performance from certain components to be transmitted to deficient components via the bus. The system remains balanced as long as the difference in the number of functional components between any two sectors does not exceed a threshold d . A sector fails when the number of nonfunctional components reaches k, and the entire system fails if either K-f sectors fail or the system becomes unbalanced, whichever occurs first. Existing studies primarily focus on forcing-down functional components or activating standby components as the primary means of maintaining balance, which often leads to component wastage. However, performance sharing can also achieve rebalancing in practice. This study contributes by developing reliability models for performance sharing in balanced systems and proposing algorithms to determine the optimal performance sharing policy maximizing system reliability. The universal generating function is utilized to calculate the balance probability and system reliability. Furthermore, a case study involving a wing system in a Solar-powered Unmanned Aerial Vehicle is presented to illustrate the effectiveness of the proposed methodology.