A fuel cell microgrid with photovoltaics effectively reduces greenhouse gas emission. A system operation optimization technique with photovoltaics and unstable power is important. In this paper, the optimal operation algorithm of this compound microgrid is developed using numerical weather information (NWI) that is freely available. A GA (genetic algorithm) was developed to minimize system fuel consumption. Furthermore, the relation between the NWI error characteristics and the operation results of the system was clarified. As a result, the optimized operation algorithm using NWI reduced the energy cost of the system. (c) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.