EPEX SPOT cleared France-Germany day-ahead at €46.58/MWh for Thursday 21 May delivery, almost double the €23.68 clear nine sessions earlier on 12 May. Germany cleared €106.35/MWh, France cleared €59.77/MWh, with Spain at €59.00 and Italy at €100.55 forming a sharp continental cluster split1. The spread reversal sits at the seventh trading session after 12 May, and Netherlands at €101.69 confirms the high-price cluster runs with Germany rather than against it.
Mechanism is the German carbon stack pricing through the cross-border basis. At €47 TTF and €75/t EUA, the German CCGT marginal cost sits near €129/MWh; French day-ahead leans on EDF's 350-370 TWh full-year nuclear guidance and the 29.3 TWh April output that priced May-26 baseload at €21.80/MWh on 28 April. Flamanville-3 declared commercial on 5 May sustains the surplus, although September's one-year overhaul will strip 1.6 GW at heating-season start. The 7 May FR-DE compression to €37.47 sat on a high-price German clear at €136.03; 21 May reverses that with Germany 22% lower than 7 May but France 39% lower still, widening the basis from the bottom rather than the top.
For desks long the FR-DE spread on cool-weather German solar overshoot, 21 May was the payout: Germany cleared 123 negative-price hours in April at a mean of -€36/MWh2, and intraday solar volatility into a carbon-stacked thermal fleet now prices the FR-DE basis as a function of German thermal dispatch rather than French nuclear surplus alone. The forward read flips in September: Flamanville's one-year overhaul strips 1.6 GW at heating-season start, reversing the French nuclear surplus that has suppressed Continental clearing since Q1, so summer extension of the FR-DE long now needs a Hormuz-driven TTF break to keep the German carbon stack alive into autumn.
