Abstract
Due to fast increase in the world of the population and global warming, designing efficient and low-polluting or clean energy systems are one of the critical problems of the century. In the recent years, most researchers are focusing on wind and solar energy sources as they freely available, complementary, their costs are becoming competitive, and they are clean. Designing optimally hybrid energy is complex as involves various mixed-type variables, tight constraints, and other complexities. In the present paper, we summarize most important optimization works related to the design of hybrid PV-wind systems, and present findings on future trends.