Electrical energy is one of the energies that humans widely use. One of the components used to generate electrical energy is solar cells. By using solar cells, energy can be stored in a battery or used directly. In stores electrical energy into the battery using DC-DC converter is still found to have a loss of power that affects the low efficiency of electricity generated. So it needs a system that can control the process of storing energy to the battery, one of which uses a DC-DC converter with Buck topology that will be used on solar panel electrical power storage system. To optimize the DC-DC Buck converter circuit, we plan a circuit simulation by considering the value of the quality factor Q of the Butterworth filter. The test results showed that the filter with a value of Q = 0.707 was of good quality with a gain of -3.1 dB. If the Q value increase, the gain will be increased, and the time it takes until the voltage stabilizes increases.