Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2006.2000.2005XuDaming Longyun Kang Binggang Cao 9200669In the design of standalone hybrid wind/photovoltaic power systems, the optimal sizing is an important and challenging task. The coordination among renewable energy resources, generators, energy storages and loads is very complicated. The sizing of standalone hybrid wind/PV power systems can be taken as a multi-objective optimization problem involving two conflicting objectives being maximization of power reliability and minimization of cost. The Loss of Power Supply Probability (LPSP), which is the index of power reliability, is obtained by simulation. The Pareto-optimal solutions are found using the elitist non-dominated sorting GA (NSGA-II) and this has been validated by solving the multi-objective problem with the tangency method, which also belongs to the-constraint method. The decision variables are not only the size of Photovoltaic (PV) panels and the capacity of batteries included in traditional methods, but also the type and size of Wind Turbine Generators (WTGs) and the tilt angle of PV panels.]]>Ai, B., H. Yang, H. Shen and X. Liao,20032814911512Ashwal, A.M.A. and I.S. Moghram,1997104351Borowy, B.S. and Z.M. Salameh,199611367375Deb, K., A. Pratap and S. Moitra,2000Deb, K.,2001Deb, K., K. Mitra, R. Dewri and S. Majumdar,20043103920931Duffie, J.A. and W.A. Beckman,1991New YorkNew YorkElhadidy, M.A. and S.M. Shaahid,1999187786Habib, M.A., S.A.M. Said, M.A.E. Hadidy and I.A. Zaharna,199924919929Hartley, L.E., J.A.M. Lozano, M.P. Utrillas, F. Tena and R. Pedros,199917291309Kaldellis, J.K.,2004773550Kellogg, W.D., M.H. Nehrir, G. Venkataramanan and V. Gerez,1998137075Lasnier, F. and T.G. Ang,1990Marion, W. and K. Urban,1995McGowan, J.G. and J.F. Manwell,199916928933Willis, H.L. and W.G. Scott,2000