How do you ensure high reliability in spacecraft power system design?

Power system reliability is critical as complete failure ends mission. Strategies: Solar array - String redundancy (extra strings for cell failures), Blocking diodes prevent reverse current, and Failure-tolerant harness routing. Batteries - Cell redundancy and bypassing, Battery charge control redundancy, and Thermal management for uniform temperature. Power electronics - Redundant units (primary/backup), Cross-strapping for flexibility, and Fault-tolerant regulators. Protection - Fuses and circuit breakers (latching vs non-latching), Isolation of failed loads, and Safe mode power-positive design. Analysis: FMEA (Failure Modes and Effects Analysis), Fault tree analysis for critical functions, Worst-case analysis for component degradation, and Parts derating. Testing: Component-level qualification, System-level hot/cold cycles, and Fault injection testing. Heritage: Use proven designs, GIDEP alerts for known issues.