Standardized Indicator Framework to Compare Rooftop PV Impacts Across Heterogeneous Urban Public Buildings: Evidence from 12 Municipal Markets in Madrid

Urban public buildings offer large rooftop PV potential, yet cross-building comparison is often hindered by heterogeneous sizes, operating conditions, and incomplete monitoring. This study develops and applies a standardized indicator framework to benchmark rooftop PV impacts across 12 municipal food markets in Madrid, Spain, using harmonized geometric, energy, PV-system, economic, and environmental metrics. Annual PV impact is screened through changes in purchased electricity derived from pre- and post-installation bills, using 12-month windows where available, while PV generation is represented by the expected production reported in project documentation. The framework includes energy intensity (kWh/m2·year), relative electricity reduction, the reduction-to-expected-production ratio, investment cost per installed capacity, and levelized cost of energy. Descriptive statistics and an LCOE sensitivity analysis are included using discount rates of 3–7%, OPEX values of 1–2% of gross CAPEX, a 25-year system lifetime, and an optional annual degradation rate of 0.5%. The portfolio comprises approximately 735 kW of installed PV, with an aggregated billing-based electricity reduction of approximately 0.994 GWh/year compared with 1.192 GWh/year of expected PV production. The median consumption reduction is approximately 40%, and the reduction-to-expected-production ratio ranges from 0.38 to 2.42. This dispersion confirms that the ratio is a screening and data-consistency indicator rather than a PV performance ratio or a causal estimate of PV generation. The framework supports transparent portfolio screening, cross-building benchmarking, identification of anomalous cases, prioritization of detailed audits, and definition of monitoring requirements for municipal PV programs.