This is an example of a space-qualified CubeSat Power Module (EPS). It has an output power buses: 3.3 V, 5 V, BCR (4.17-4.34 V) and battery raw with BCR efficiency: 95% and 3 Photovoltaic input channels.
The EPS is one of the most important modules of any spacecraft and its functioning is mission critical. It provides to each subsystem and payload the required power over the whole mission.
It has undergone successfully spacecraft environmental testing to ensure it can withstand the harsh space environment. The graphics are kindly provided by EnduroSat http://endurosat.com