Power Supply unit
The rover requires power to operate. The main source of power for each rover comes from a multi-panel solar array. They look almost like "wings," but their purpose is to provide energy, not fly.
When fully illuminated, the rover solar arrays generate about 140 watts of power for up to four hours per sol (a Martian day). The rover needs about 100 watts of power to drive.
The power system for the Mars Exploration Rover includes two rechargeable batteries that provide energy for the rover when the sun is not shining, especially at night