Capture rates explained: the number that decides every solar and wind business case

A solar park does not earn "the power price". It earns the power price in the hours it produces — and because every other solar park produces in the same hours, those are increasingly the cheapest hours of the day. The gap between the average price and what wind and solar actually receive has a name, three names in fact: the capture rate, the market value factor, or in German — the language of the market where this number carries legal weight — the Marktwertfaktor.

The four numbers, precisely

For a technology in a bidding zone over a month (or day), at native market resolution:

A capture rate of 100% means the technology earns the average price. Solar in Germany ran near 90% a decade ago; in strong months of 2026 it prints below 60%, and in April 2026 France recorded 8.4%. That slide — price cannibalization — is the single most consequential number in renewable project finance: it sets PPA discounts to baseload, drives merchant revenue models, and is the entire reason battery arbitrage revenue is booming in the same zones where capture is collapsing.

Why the number is slippery

Two published capture rates for the same zone-month rarely match, for boring reasons: hourly vs 15-minute averaging (the market moved to 15-minute settlement in October 2025 — mixing resolutions without interval weighting biases everything), different generation series (TSO EEG feed-in estimates vs ENTSO-E actuals), and whether negative-price hours are handled honestly. We publish every formula, the freeze policy and the null rules — and for Germany we reconcile monthly against the official EEG Marktwerte rather than asking you to trust us.

Where to get the numbers

The Voltcast Capture Index publishes monthly market values, capture rates and negative-price shares for solar, wind onshore and wind offshore across every European bidding zone — provisional rows recompute daily while ENTSO-E actuals revise, frozen rows never restate. The whole monthly index is a free CSV; the keyless API is GET /api/v1/public/capture/{zone}; and the explorer values a generation profile — fixed tilt, tracker, east-west — against any zone. Free to cite with attribution.