An electrical power supply apparatus is disclosed. The apparatus comprises a plurality of rechargeable battery components, a solar panel and a control unit enclosed in a main body and electrically connected to the rechargeable battery components and the solar panel. The control unit controls the apparatus to alternately use each rechargeable battery component for outputting electrical power, and alternately charging each rechargeable battery component using the solar panel. The control unit further comprises an orientation sensor for detecting the orientation of the main body and determining the state of the apparatus based on the signal received from the orientation sensor.