The projects "Energieschwamm Bruck" and "Smart Exergy Leoben" are dedicated to develop and analyse a smart future municipal energy system. Both projects focus on the concept development for energy sources like heat, gas and electricity while considering future infrastructure and a possible hybridization. In the course thesis, which is based on these projects, the electricity networks of the Styrian cities Bruck an der Mur and Leoben are modeled by using the cellular approach. As a first step is verified if the model of a reduced network for the above mentioned cities with tight industry is accurate enough. Afterwards bottlenecks in the grids and effects of the integration of renewable energy potentials were identified. A pre-existing cell classification is the base for the attribution of consumer, supply and storage structures. In order to generate temporally resolved load profiles, the combination of measurements and standard-load-profiles are used for all structures. The model is created in the software program NEPLAN. Each cell receives a node, which in each case assigns the associated structure. After a first load-flow calculation it is considerable to compare the results with the real network data in order to find out any differences. The reactive power losses which are generated in the reduced lines, are simulated in the model. The calculation results confirm the approximation with the cellular model. Still there are some differences between the load flows, so it is important to consider the topic of the reduced lines and their correct modelling. In a next step the supply integration of photovoltaics potentials are integrated into the model. During a new load flow calculation the focus is the prevention of possible bottlenecks. With this consideration the violation voltages limit of some local network transformers as well wire- and transformer-overloads are recognized. The calculation shows that the transformer is overloaded if the energy-recirculation into the 110 kV levels too high. According to this the maximum integrable photovoltaic potential is defined by the maximum capacity of the transformers.