The transition from fossil-based to renewable energy systems requires the integration of decentralized energy technologies such as solar photovoltaic (PV). Therefore, it is essential to evaluate multi-energy systems with different spatial and time resolutions. This study presents the first results of a multi-energy system model for the evaluation of district-level energy scenarios in Swiss communities. The model assesses both heat and electricity demand while estimating the potential for integrating decentralized renewables and retrofitting fossil heating systems with low-emission alternatives. Computations are carried out with an hourly resolution and timeframes of one year. The model was applied to a Swiss community, assessing solar PV integration and the effect of replacing fossil heating systems. It was shown that the replacement of fossil-based heating systems poses a significant potential for reducing carbon emissions. The impact of solar PV integration diminishes with increasing share of utilized potential due to a demand-supply mismatch and lack of storage and demand-side flexibility considerations.