On March 30, FCR-D Up cleared at €25.00/MW — flat, zero intraday spread, the kind of clean pricing that makes dispatch planning trivially easy. Twenty-four hours later it was €3.94/MW, an 84% collapse. The 7-day average dropped to €4.81/MW, with the intraday range swinging between €1.83 and €6.95. The 7-day high of €11.51 (recorded March 24) already felt like a different market.
Then it got worse.
The Outage
From April 1 through April 5, FCR pricing data went completely dark. Swissgrid’s feed returned null values, sources flagged as “demo-fallback.” Five days of zero signal. No clearing prices, no intraday ranges, no basis for FCR commitment decisions. The entire reserve revenue stream simply vanished from the calculation.
This wasn’t a market event — it was an infrastructure event. And it exposed a dependency that matters more than any individual price print: if your dispatch optimisation relies on continuous FCR data, a feed outage doesn’t just reduce revenue. It eliminates an entire operating mode.
When the signal recovered on April 6, FCR cleared at €4.55/MW average with a €2.41–€8.76 range — still 8.4% below the 7-day mean. The market came back, but it came back weak.
Revenue: The Damage
MTD actuals against target, day by day through the outage:
April 1: CHF 10.48 actual vs CHF 66.18 target — 84% shortfall. The first day of pure arbitrage-only operation with 0.5 confidence. Essentially flying blind.
April 2–3: CHF 73 and CHF 136 against targets of CHF 132 and CHF 199. The shortfall narrowed to 45% then 31% as arbitrage execution improved, but the gap remained structural — you can’t arbitrage your way to an FCR-shaped revenue curve with a 2 MWh battery.
April 4–6: Progressive recovery — 24.8%, 20.8%, 18.2% below target. By April 6, with FCR data back at €4.55/MW, the combined revenue hit CHF 828.64 against a CHF 1,012.94 target. Better, but still underwater.
For context, the March 30 full-day performance hit CHF 17,710 against an CHF 18,905 target — a CHF 1,195 shortfall on a day with €25/MW FCR. Even the good days were missing target.
The EPEX Lifeline
The one consistent element: EPEX Spot day-ahead pricing held remarkably stable. Off-peak at €80/MWh, peak at €120/MWh, a clean €40/MWh gross spread. For a 2 MWh system, that’s €80 gross per full cycle, roughly €66 net after 82% round-trip efficiency — which, somewhat neatly, aligns with the CHF 66.18 daily target during the outage period.
Solar irradiance shaped the intraday texture. April 3 and 5 saw peak irradiance above 645 W/m² with near-zero cloud cover, suppressing midday prices and creating sharper morning and evening ramps. The optimal windows stayed consistent: charge 00:00–07:00, discharge into the 07:00–10:00 morning peak or the 17:00–21:00 evening peak, avoid the 11:00–15:00 solar suppression window.
The spread is reliable. It’s just not enough to carry the whole revenue target alone.
Mode Switching Under Pressure
The week forced a live test of the three-mode framework: FCR-Active, Trading (pure arbitrage), and Mixed. The decision matrix is straightforward on paper — FCR above €20/MW means go FCR-Active, below €5/MW with decent spreads means Trading, the middle ground gets Mixed. But when your FCR feed goes to null, the matrix collapses to a single row.
During the outage, operations ran Trading mode at 0.5 confidence — the lowest operational confidence level that still permits execution. The constraint isn’t the battery (94% health, 350 cycles, holding well) or the market (€40/MWh spread, stable). The constraint is information.
On April 6, with FCR back at €4.55/MW, the strategy shifted to Mixed: reduce FCR commitment during low-price windows (€2.41–€3.15/MW), execute arbitrage during the 02:00–07:00 charge and 11:00–14:00 discharge windows, resume full FCR-Active from 15:00 when prices recovered to €5–€8.76. That’s the kind of intraday mode-switching that extracts value from a weak FCR market — but it requires the data to be there.
What This Week Means
The FCR collapse from €25 to sub-€5 is seasonal — spring load reduction, fewer frequency events, standard shoulder-season dynamics. That’s not news. What’s news is the five-day data outage revealing that the revenue model has a single point of failure in the Swissgrid feed.
Two things to watch. First, whether FCR data reliability stabilises or whether the April 1–5 outage was the first of a pattern — if Swissgrid’s feed becomes intermittent through spring, the Mixed mode strategy needs a fallback that doesn’t crater confidence to 0.5. Second, whether sub-€5/MW FCR pricing is the new spring baseline or whether the March 24 high of €11.51 still represents a reachable ceiling. The answer determines whether Mixed mode can recover enough FCR revenue to close the 18–20% target gap, or whether April becomes an arbitrage-only month.
The batteries that survive this market aren’t the ones with the best dispatch algorithm. They’re the ones with data redundancy.