In this study, the planned facilities for the Teuri and Yagishiri Islands interconnection microgrid (small-scale power network) systems were surveyed. In the small and isolated islands of this area, the wind state changes dramatically with location and influences the production of electricity by wind power generators and solar cells. Based on the estimated values of the electrical power output by renewable energy, a method of optimizing the operation of the main electrical and heating equipment was developed using a genetic algorithm (GA). The optimum conditions for installing the wind power generators include wind blowing from all directions at high speed throughout the year. Operation of the photovoltaic power plant is favored by high winds, which produce a large cooling effect over the solar cells. Adoption of the proposed analysis method will optimize the operation plan of the isolated island microgrid with a large utilization rate of renewable energy. The proposed operation plan obtained the effect of a planned utilization rate of annual renewable energy of 40% or more. The large rate of renewable energy is taken as the proposed microgrid without a battery, and the high effect was obtained by the proposal design method of this study. (C) 2018 Published by Elsevier Ltd.