An Integrated Renewable Energy Optimization Model (IREOM) model has been developed for sizing and optimization of renewable energy systems based on seasonal variation in the load profiles of the study area. An attempt has been made to develop correlations between renewable energy system sizes and their capital cost for the user specified system sizes. The developed correlations were used for the analysis of IREOM model using user specified system sizes and compared with manufacturer specified system sizes. The cluster of seven unelectrified villages having micro-hydro power, biomass, wind and solar energy resources in the state of Uttarakhand. India has been considered for the implementation of IREOM model. Based on the results obtained from the proposed model, suitable sizes of renewable energy systems have been suggested. (C) 2011 Elsevier Ltd. All rights reserved.