Unified framework for the assessment of rooftop solar PV electricity generation potential in EU-27

Achieving climate neutrality in European cities requires large-scale deployment of renewable energy, with solar photovoltaics (PV) expected to play a central role under EU initiatives such as the European Green Deal, REPowerEU, and NetZero Cities. Although rooftop PV potential has been examined in individual cities, differences in data sources and methodological assumptions hinder direct comparison across Europe, and a harmonized assessment covering all 27 EU capital cities remains lacking. This study fills that gap by applying a unified framework integrating Copernicus urban datasets, a 16-year climatological record (2008–2023), and PVGIS performance simulations. The effects of urban shading, cloud cover, and aerosol loading are quantified separately through three modification factors (SMF, CMF, AMF), enabling explicit attribution of irradiance losses across cities. Exploitable rooftop area ranges from 2.6 km 2 in Valletta to 72.2 km 2 in Paris, translating into annual generation potential of 0.2 TWh to 3.8 TWh respectively. Obtained estimates suggest that rooftop PV can meet or exceed household electricity demand in cities such as Luxembourg (180%), however data across the EU capitals indicates that there is an empirical ceiling of 35% for rooftop PV as a standalone measure. Annual avoided CO 2 emissions may reach up to approximately 1 million tCO 2 e, while net economic revenues may exceed 330 MEUR current market values s. The findings propose a harmonized approach yielding metrics that support a differentiated approach to urban solar policy, identifying where rooftop PV can make a major contribution to local electricity supply and where complementary measures remain necessary.