<p>Rising photovoltaic (PV) penetration and intensifying climate forcing raise growing concerns about the long-term adequacy of solar electricity supply across Europe. Yet, probabilistic reliability-based assessments using the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate projections remain limited. This study applies a reliability framework coupling daily outputs from a CMIP6 multi-model ensemble (Shared Socioeconomic Pathways (SSP)5–8.5, 2015–2100) with a physical–empirical PV model, evaluated at eight representative European capitals (London, Paris, Berlin, Madrid, Rome, Warsaw, Stockholm, and Athens) spanning northern to Mediterranean regimes. Using daily shortwave irradiation, air temperature, and wind speed as drivers, PV-specific yields were translated into reliability indicators, the reliability index (β) and exceedance probabilities (P50, P90, P95), across thresholds from 1.5 to 4.0 kWh kWp⁻¹ day⁻¹. Results reveal a clear north–south divide that persists but evolves over time. The continental mean yield remains near 2.9 kWh kWp⁻¹ day⁻¹, with Mediterranean and southwestern regions gaining up to + 0.10 kWh kWp⁻¹ day⁻¹ by late century, offsetting modest northern declines of − 0.05 to − 0.15. Reliability decreases almost linearly with higher thresholds (Δβ/ΔT ≈ − 0.25 (kWh kWp⁻¹ day⁻¹)⁻¹), with an ensemble-mean β ≈ 0.98 (≈83% reliability). At the key adequacy level of 2.5 kWh kWp⁻¹ day⁻¹, Mediterranean capitals such as Athens, Madrid, and Rome sustain β = 1.3–1.6, corresponding to P90–P95, considered highly reliable for solar adequacy planning. Western sites (Paris, London) remain within P84–P87, while northern cities approach P70–P80, reflecting moderate but acceptable reliability levels. Temporal trends show gradual strengthening of β in the south and southwest (+ 0.005 per decade) and near-stability elsewhere. These results demonstrate that even under high-emission forcing, much of Europe, especially the mediterranean and western regions, can maintain P90-level adequacy, providing confidence in PV reliability and guiding adaptation strategies for resilient, low-carbon energy systems.</p>