This paper presents a simulation model of green energy devices, which is developed for analyzing energy balance of a micro-grid and for optimizing its management. Several renewable energy based electricity production and storage are modeled and analyzed in the making of strategies for sustainable micro-grid management. In this study, two different simulation models are described, which call a “long-term simulation model”, and a “detailed short-term simulation model”. The first one is a high speed simulation model; it aims for prediction of the energy supply and demand balance of the micro-grid. In contrast, the second one is an accurate verification model; it use for detailed signal analysis of the devices and system. A case study, renewable energy model using photovoltaic, fuel cell, biomass and tidal power generation, is conducted and its simulation result is presented.