Major Outage

A technical fault on the offshore substation transformers forced the Saint-Nazaire wind farm into a full production stop for around three weeks at the start of December 2023, with poor weather initially preventing repairs offshore. Partial recovery began on 21 December 2023, when the park resumed operating at roughly half capacity while repair work continued, with full operation only restored in early February 2024 once intervention conditions on the substation allowed the remaining work to be completed. Output for December 2023 dropped to about 252 GWh — well below the 800 GWh recorded in November 2023 — though EDF Renewables noted at the time that the cumulative impact on the wind farm's first full operating year would remain limited. The incident is the first significant operational outage on France's first commercial-scale offshore wind farm and was attributed by the operator to transformer-side faults at the integrated offshore substation rather than to the array or export cables; the OFTO-side 225 kV export link operated by RTE was not implicated. In a subsequent interview, EDF power solutions' offshore wind asset-management director described the impact on the annual production curve as "marginal" compared with the dominant wind-resource signal, and the operator confirmed that no permanent damage to the substation electrical equipment resulted from the event.