This paper presents the second Electric Power Supply (EPS) prototype designed for supplying power to the Space Plasma Ionic Charge Analyzer (SPICA) CubeSat. In order to power the CubeSat with higher efficiency, Gallium Arsenide (GaAs) solar panels are mounted on each side of the cube, converting solar power into electrical energy. Solar cell area limitations require maximizing the available electrical energy generated. To extract the utmost available power from the solar panels, a Maximum Power Point Tracking (MPPT) method that uses the optimal duty ratio of a DCIDC converter isimplemented. The DCIDC converter in combination with high performance GaAs solar panels and a MPPT technique will not only improve the power extraction but will also further increase efficien cy.