The purpose of the present study is to develop a useful analysis for solar power systems consisting of a concentrator with a receiver (i.e., a collector), an engine/generator, and an operational control system. In the present paper, the collector efficiency is evaluated by considering the sun's position as it varies with time. The validity of the engine simulation model is examined for a Stirling engine, named 'NS30S' developed by SANYO Electric in the project of the New Energy Development Organization (NEDO). In addition, an engine control algorithm is proposed to achieve better performance using solar heat. The overall system performance is predicted by incorporating both the collector and engine/generator models into the algorithm. This enables exact estimation of the overall performance, compared with methods reported in earlier studies. Our simulation model was used to predict the overall performance of a solar Stirling power module of 25 kWe net. Okinawa in Japan appears to be a suitable location to introduce the module. The calculated results show that the system generates 40 MWh/year and that the average system efficiency is about 25%.