Nanosatellites and CubeSat platforms require power management techniques which function effectively because their size and weight limitations together with their power budget restrict their operational abilities until their mission duration finishes. The existing small satellite system design maintains continuous operation for all onboard equipment, which leads to excessive power consumption and decreased mission duration. The research presents a hybrid power conservation system which combines hardware and software components to solve power conservation issues present in small satellite systems. The system integrates hardware-based power management components which consist of power distribution networks and load switching equipment with onboard microcontroller systems that execute intelligent power management through software. The system establishes three operational modes, which include normal operation power-saving mode and survival mode, to control power consumption based on battery status, mission demands and subsystem operational status. The system disables all non-essential subsystems during low-energy operations while keeping necessary functions active to protect mission security. The system operates under evaluation through simulation analysis, which uses actual subsystem power models together with orbital illumination patterns for assessment. The results show that the system achieves a 25-35% reduction in average power consumption, which leads to longer mission time because traditional systems maintain continuous operation of their subsystems. The proposed approach demonstrates an affordable lightweight solution which enhances energy efficiency for nanosatellite missions, making it appropriate for upcoming long-duration CubeSat and small satellite missions.