In order to accomplish the reliable planning and operation of large interconnected power systems with high penetration of renewables, knowledge of the impacts on individual transmission lines and power plants within the system is required. This may be accomplished using high-resolution optimal power flow simulations with which different scenarios can be assessed. This paper presents detailed numerical weather prediction models that can be used for accurate predictions of solar and wind generated electricity. Furthermore a high-resolution power demand model that accounts for the spatial and temporal variations of different sectors is presented. The models are demonstrated in the case of one-year hourly resolution simulation of the central European power system.