How much does a battery earn in Germany? The open numbers

Germany has Europe's largest grid-scale battery pipeline, the deepest intraday market, the reBAP imbalance regime, and — since the solar buildout collided with a nuclear-free, increasingly coal-free grid — the continent's most reliable daily price spread. Every developer deck, lender memo and optimizer pitch about DE-LU storage leans on a revenue number. This article explains where our number comes from, what it shows, and how to use it without fooling yourself — all of it from the free Battery Revenue Index, updated daily.

The shape of the German battery day

The DE-LU revenue engine is the solar duck. Midday photovoltaics push prices toward — and increasingly below — zero; the evening ramp pays. A 2-hour battery charging in the 12:00–15:00 trough and discharging into the 19:00–21:00 peak captures that spread nearly every day of the summer half-year. The days that make the annual number, though, are the outliers: negative-price middays (Germany leads Europe in negative hours — the tracker is here) paired with tight evening peaks, and the winter Dunkelflaute days when the stress index lights up and the evening hours clear in the hundreds.

Duration economics, visible in one chart

The 1h/2h/4h split on the DE-LU page is the duration argument settled with data. Per MW of power, a 4-hour system always earns more than a 2-hour system — it sells more energy — but not twice as much, because hours five through eight of the spread are shallower than hours one through four. Per MWh of capacity (what you actually pay for), the ordering inverts. That tension — revenue per MW versus cost per MWh — is the entire duration debate, and you can now watch it move daily rather than argue about it annually. Germany's evening ramp has been lengthening as solar deepens the trough, which is the structural case the 4h developers are making; the daily index is where you check whether the data agrees.

Arbitrage isn't the only stack

The same megawatt can, instead, stand ready in the reserve markets. Our DE-LU rows carry the day's FCR capacity settlement (the four-hour symmetric blocks from regelleistung.net) and the aFRR capacity prices alongside the arbitrage figure — side by side, never summed, because full arbitrage and full FCR are alternative lives for the same asset. The historical pattern every German operator knows: FCR was the easy money until the fleet saturated it (prices fell hard through the early 2020s), and the marginal battery's revenue migrated to energy arbitrage — which is why the arbitrage index is the number that now decides investment cases, and why aFRR energy-market co-optimization (not yet in BESS-v2, stated plainly in the methodology) is the frontier the optimizers compete on.

From ceiling to bankable number

Our index is a perfect-foresight ceiling and says so on every surface. Getting from the ceiling to a project number is three haircuts, and the explorer applies each one interactively: forecast error — flip the foresight toggle from "perfect" to "Volt forecast" and watch the capture rate: the schedule is re-chosen each day on our pre-auction P50 and settled at actual prices, no lookahead; availability — maintenance, curtailment, connection limits (the slider goes to 70%); and degradation — price each cycled MWh at your cell-warranty cost and the marginal summer cycle sometimes stops paying, which the engine then honestly refuses to run. What's deliberately out: grid fees and taxes (too regime-specific to bake into a benchmark) — bring your own, the explorer's output is the clean revenue line they subtract from.

And the number for next week

The platform's third layer is the one no incumbent publishes: the 7-day expected revenue forecast for DE-LU with P10–P90 bands, derived from our quantile price models and scored weekly against the realized index, misses on the record. If you run a battery, it's a free dispatch-planning signal; if you're evaluating one, four weeks of watching forecast-vs-realized tells you more about revenue uncertainty than any static sensitivity table.

The live numbers: battery-revenue/de-lu. The full daily CSV back to 2015, free with attribution: download. The launch story and the full three-layer design: the platform article.