Computer analyses of satellite power systems have generally been divided into two categories. The first may be referred to as System Level Studies, which generally develop mathematical relationships for the power system components, and which are used for ‘high level’ examinations such as energy balance analysis and simplified dynamics studies. The second category of analyses is Circuit Level Studies, which develop circuit level models of the power system electronics, and are typically used for studies such as stability analysis, load transient studies and bus impedance characterizations. Unfortunately, the two categories of analyses are generally not integrated. That is, it is not usually possible to begin with a system level model, and develop it into a detailed circuit model for further studies. In the past, software tools that were suitable for system level studies were not convenient or practical for circuit analysis. Conversely, the electronics circuit analysis programs did not have the capabilities needed to characterize the major power generation, energy storage, and regulation blocks of the power system. However, using the MicroSim PSpice® circuit simulator, MRJ personnel have successfully integrated these two approaches to power systems analysis. Several examples of its usefulness in modelling power system components will be provided, followed by an illustration of system level dynamics analysis.