Electrical Power Systems (EPS) are essential subsystems in space systems. Either new or increased requirements in the frame of current projects influence design and technology for power generation. conditioning, distribution and energy storage. This paper, though, does not deal with these topics but with another new requirement, i.e. the introduction of intelligent controllers into the subsystem. Based on the EPS design for the European space station the paper discusses the subsystem architecture with respect to data management and topological aspects leading to a bus concept for internal data transmission. Furthermore, functional requirements for the on-board subsystem software are explained and topics like redundancy, built-in-test-equipment (BITE) and future use of expert systems are addressed.