Distributed power generation technologies such as wind turbines, solar cells and co-generation systems are gaining the opportunities of participating into grid power systems due to rapid technology improvement. The purpose of this study is to analyze potential of autonomous small scale decentralized power supply systems which involves distributed power sources and electricity storage facilities, through the numerical simulation of their coordinated operation based on the signals of electricity prices. Here we assume that each decentralized system communicates only with its neighboring systems, and that electricity is traded intermittently between the systems on demand.