We reconciled our capture index against the official EEG Marktwerte

Germany settles billions of euros of EEG subsidy every year on one published statistic: the monthly Marktwert per technology, computed by the four TSOs and published on Netztransparenz. It is the closest thing the capture-rate world has to an official answer sheet. So when we launched the Voltcast Capture Index — the same statistic, computed independently from ENTSO-E generation actuals and published day-ahead auction results — the first thing we did was grade ourselves against it. In public, every month, automatically.

The honest read

In ordinary months we land within a couple of percent — June 2026 solar agreed to +0.4%. In heavy negative-price months the gap widens systematically: April 2026 solar shows +45% — which sounds alarming until you see it is €5.9/MWh absolute on an official value of €13.17, and until you understand why. The official calculation weights hours by the TSOs' own EEG feed-in series, which attributes more (largely rooftop) solar to the negative midday hours than ENTSO-E's transmission-metered actuals do — pulling the official value further down exactly when prices go negative. Same physics, different meters.

We could have quietly tuned our series to match theirs. We did the opposite: the divergence is published, its mechanism is documented on the methodology page, and no marketing copy carries a tolerance number until the generation-basis gap is fully characterized. A reconciliation you can't explain is worse than none — and a statistic that only matches the official one by construction would tell you nothing new. Independence is the product.

Official values: Netztransparenz Monatsmarktwerte (EEG settlement basis). Ours: Voltcast Capture Index, methodology capture-v1 — free with attribution.