The ISIS Electrical Power System (iEPS) is the second-generation compact power system for nanosatellites. It is an off-the-shelf Electrical Power System available in three standard configurations (Type A/B/C), ideal for powering 1U – 3U CubeSats. The system leverages wide bandgap semiconductor technologies, implementing GaN-FETs to improve solar power conversion efficiency and performance. It is equipped with an integrated heater, hardware-based Maximum Power Point Tracking (MPPT) and hardware voltage and over-current protection. The iEPS provides 3.3V and 5 V regulated buses, as well as an unregulated bus. An add-on daughterboard allows additional configurations to suitably power the system and payload instruments.