04What happens when supply runs tight?
Paying to keep the lights on when the wind drops
Can the plants that run on demand cover the days when wind and solar all but stop, and what does it cost to keep them ready?
Over the 12 months to 14 October 2026, Germany saw about 481 hours of low renewable output, the longest low-wind-and-sun spell running 52 hours, against a peak residual load near 40 GW.
To insure against that, the German parliament (Bundestag) passed a capacity law, the StromVKG, on 9 July 2026. It sets auctions in 2026 and 2027 for 11 GW of firm capacity, plants that can run whenever they are asked, paid to stay available from 2031 on contracts of up to 15 years.
The European Commission approved the scheme on 2 September 2026 and expects it to cost €1–3 billion in 2031 and €0.9–2.3 billion a year from 2032 to 2045. Consumers pay it through a levy, and the levy figure is an estimate until a follow-up law sets it.
Why a grid pays for plants that may never run
A power system has to meet demand in its hardest hours. In a grid built on wind and solar, those are the dark, still winter days of a Dunkelflaute, when both all but stop, sometimes for days at a time. Grid batteries today typically hold one to two hours of output, far short of a spell that lasts days. So the grid still needs firm capacity: plants that can run whenever they are asked, whatever the weather.
A market that pays only for the energy sold can leave such plants short of money. A gas plant kept for the worst few days of the year sells little power and may not cover its costs, so owners close old plants and hesitate to build new ones. A capacity mechanism pays plants to be available, whether or not they run, and recovers the cost from consumers through a levy.
The first chart shows what the European Commission expects Germany's scheme to cost each year, as a range. The second compares how much of demand wind and solar covered during a Dunkelflaute with an ordinary hour, and that gap is what such a scheme is meant to fill.
Great Britain has run a capacity market since 2014, and France has had a capacity mechanism since 2017. How much firm capacity Germany needs depends on imports, storage, demand that can pause and how many old plants stay open, and published studies reach different answers. Dunkelflaute records each spell since 2021, and Storage tracks the batteries that shorten the gap.
Questions
How often does Germany run short of wind and solar power?
Over the 12 months to 14 October 2026, Germany saw about 481 hours of low renewable output; the longest spell of low wind and sun ran 52 hours, against a peak residual load near 40 GW. Residual load is demand minus wind and solar, the power other plants and batteries must cover.
What will Germany's capacity law cost?
The European Commission, approving the scheme on 2 September 2026, expects it to cost €1–3 billion in 2031 and €0.9–2.3 billion a year from 2032 to 2045. The law, passed on 9 July 2026, auctions 11 GW of firm capacity; consumers pay through a levy, which is an estimate until a follow-up law sets it.
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