Solar PV is fundamentally reshaping how Germany’s fossil fleet operates during the summer months.
In 2021, the last full-nuclear summer before the phase-out was completed in April 2023, fossil thermal generation (gas, coal, and lignite) ran almost flat at 18–22 GW throughout the day.
By 2025, the same fleet dips to around 7 GW at midday before ramping sharply into the evening.
With German power consumption already back to pre-pandemic levels in 2021 according to AGEB, the change is not about demand — it is about the shape of residual load.
Solar PV midday peaks grew from around 24 GW in 2021 to around 36 GW in 2025. In May 2026 year-to-date, average midday output has already reached approximately 38 GW.
At the same time, around 7 GW of nuclear capacity and a portion of coal and lignite capacity exited the system.
The impact is particularly visible in the evening ramp. Average ramp rates increased from around 0.52 GW/h in 2021 to around 1.52 GW/h in 2025 — roughly three times steeper.
It will be worth watching how this summer unfolds. Late spring 2026 has already produced some interesting market dynamics.
All figures are hourly averages over the period (for example, mean solar output at each hour of the day between June 1 and August 31).
