Optimal power generation and storage technology suites must be selected based on the overall spacecraft mission and hardware design to insure a minimum system cost. Several new technologies in solar generation (high efficiency multi-junction GaAs-based cells, concentrator arrays, thin film cells, etc.) offer increased performance and/or reduced system-level cost. The savings at the array level often benefit the overall system performance in terms of drag, mass, inertia, and propellant loading. In addition, battery technologies often impact the spacecraft thermal control system and overall dry mass. This paper discusses the design algorithms implemented and executed at The Aerospace Corporation to determine optimal power subsystem suites as a function of spacecraft design and total system cost. The analysis includes ballistic coefficient, disturbance torque, station keeping, and temperature control requirements and links these parameters to design impacts in the propulsion, attitude determination and control, and thermal subsystems. In addition, the algorithms include roll-ups for mass and power and most importantly system cost, including launch. This type of analysis is essential for selecting power system components and determining optimal spacecraft design to minimize mass and/or cost as a function of mission performance parameters, and must be continually revisited as new technologies emerge to determine their best applications.