This paper presents a new architecture for CubeSat Electric power system (EPS) to achieve higher efficiency compared to the state-of-the-art architectures. In the literature, several architectures are presented for the CubeSat EPS, and among them, two architectures are utilized in commercial products. The efficiency of the architectures that depend on the number of power converters between the source and load is critical, as it affects the cycle life of the battery. The proposed architecture achieves only one power conversion stage between source and load in all modes of operation and thus, it achieves higher efficiency compared to commercial EPS architectures. Further, the simulation tests are performed for the proposed EPS architecture based on the 1 U CubeSat specifications, and results are presented to demonstrate the performance of the proposed EPS architecture.