The Cost of Darkness: A Three-Layer Event Study of Photovoltaic Generation and Electricity Prices During the August 2026 Solar Eclipse over Spain

The rapid decarbonization of European power grids has elevated solar photovoltaic (PV) generation to a central pillar of the energy mix, yet high penetration levels introduce volumetric and ramp risk. On 12 August 2026, a total solar eclipse over Spain caused a forecastable contraction in PV generation, offering a natural stress test for both system operations and electricity markets. The novelty of this study lies in its explicit three-layer decomposition of the event into the physical generation shortfall, the operational ramp requirement, and the day-ahead price co-movement, together with an identification-aware treatment that separates anticipatory bidding from a causal price effect. Using 15 min resolution data from Red Eléctrica de España (REE) and the Iberian Energy Market Operator (OMIE) for August 11–13, the analysis documents a peak PV shortfall of 78.9% (3.00 GW) at 20:45 CET and a cumulative deficit of 4.48 GWh during the 19:30–22:00 window, with ramp rates 57% steeper than the clear-sky baseline. Day-ahead prices exhibited a peak premium of +45.43 €/MWh (+24.6%) at 20:30 relative to a structural counterfactual; however, because day-ahead auctions clear before delivery, this price movement is interpreted as anticipatory bidding rather than a purely causal shock, an identification challenge that is explicitly discussed and left to future work using intraday and balancing market data. An illustrative economic decomposition is also provided, together with a discussion of the conditions under which co-located battery energy storage (BESS) could mitigate asset exposure to similar events, offering insights ahead of the 2 August 2027 eclipse in southern Spain.