The accelerating deployment of residential solar photovoltaic (PV) systems across Europe, driven by the recast Energy Performance of Buildings Directive (EPBD, 2024/1275/EU) mandate for zero-emission buildings by 2030, demands spatially resolved performance benchmarks at the provincial scale. Generic European-level models lack the resolution required for building-level design and investment decisions, and province-specific performance data for Central European climates remain scarce in the peer-reviewed literature. To the authors' knowledge, no prior study has presented a systematic, multi-province performance evaluation of a standardised 12 kWp grid-connected rooftop PV system across all 13 administrative provinces of the Czech Republic. Meteorological inputs were obtained from Meteonorm 8.1 and integrated into PVsyst v7 simulation software.