This paper tries to develop an efficient methodology for optimizing size of wind-photovoltaic hybrid energy systems. Since finding optimal size belongs to discrete optimization problems, optimization algorithm must be able to effectively handle this kind of problem. For this aim, a Discrete Harmony Search (DHS) algorithm is developed. The proposed methodology is easy to implement, can efficiently handle the discrete problem and can quickly find a good solution. The obtained results show that the proposed methodology finds promising results in less than one second. (C) 2013 Elsevier Ltd. All rights reserved.