This paper investigates the solar energy systems potential in a Nearly Zero Energy Building (NZEB) in order to reduce the use of non-renewable energy. The Hooke-Jeeves optimization scheme (implemented in the software GenOpt) is employed to find the best configurations of the solar thermal panels (ST-panels), photovoltaic panels (PV-panels) and hot water storage tank that reduces the overall cost, including the energy demand from other supplies. Various locations with different climatic conditions (temperate, continental, and oceanic climate) were analyzed. Solar collectors’ area, solar collectors’ scope and volume of hot water storage tank are set as the optimization variables, while the overall cost, consisting of investment costs and operating cost, is the objective function to minimize. The optimization results show that it is preferable to dedicate a larger roof area to photovoltaic collectors in the locations where the cooling loads are higher and that a larger roof area should be reserved to thermal solar panels in the locations where the heating loads are higher.
