Isolated renewable energy system offers promising options to electrify communities located in remote areas where the utility grid is not available or extension of the grid is not economical. Proper sizing of renewable energy conversion system along with storage capacity is the key element to achieve the technical and economical feasibility of such renewable-based isolated system. In this paper, a methodology, based on the concept of Power Pinch Analysis, is proposed to determine the minimum renewable generator area, its extreme limits, and the corresponding storage capacity. The proposed methodology accounts for the uncertainties associated with the renewable resource to size the overall system with a predefined reliability. The concept of the chance constrained programming is applied within the Pinch Analysis framework to incorporate stochastic nature of the renewable energy resources. The applicability of the methodology is demonstrated with an illustrative example of photovoltaic-battery system and verified using sequential Monte-Carlo simulation approach as well as through annual simulation of the system with actual isolation data. (C) 2017 Elsevier Ltd. All rights reserved.