This document discusses the importance of modelling energy systems with detailed representations of surrounding regions. It presents a case study comparing different levels of detail in modelling Germany's energy system within the context of surrounding countries like France, Poland, Austria and others. The study uses EnergyPLAN to model each country's system individually and also connected together. It finds that modelling with greater detail, representing each surrounding country separately rather than aggregated, reveals more nuanced results about how increased wind power in Germany may affect its own CO2 emissions versus the overall connected system's emissions. The level of geographic detail is important for policymakers and researchers to understand impacts across interconnected energy infrastructures.