The paper presents a case study of an office building with a façade integrated PV system in Norway. Due to the urban surrounding the PV system is subject to significant overshadowing. The aim is to optimize the solar energy potential of the building in order to propose improved alternatives to the current system applying a multi-level simulation approach. The first level is performed to calculate the maximum solar potential on the building envelope in an unobstructed scenario. The second level examines the shading effect on the building in its urban context. The analyses allow localizing the areas of the building with the highest solar potential. In the third level, the energy output of different solar technologies (solar thermal and PV) is evaluated. The results demonstrate that the solar potential analysis in the early stage is important for choosing the most performing system.