In this study, optimum dimensions of Solar Domestic Hot Water System (SDHWS) were determined according to initial capital cost and energy consumption cost in different locations of Turkey. Typical Meteorological Year (TMY) data of 12 different locations which represent climatic characteristics of Turkey were used. Analysis was performed by using Particle Swarm Optimization / Hooke-Jeeves (PSO/HJ) hybrid algorithm which is a part of EnergyPlus®-GenOpt® programs. For each location, optimum number of solar collectors and hot water storage tank volume was determined. Initial investment and energy consumption costs decreased 6.1% for Gaziantep whereas solar fraction increased 42.8% for Ankara. In average, 4.5% decrease in initial investment and energy costs and 35.4% increase in solar fraction were obtained.