I-SEM Daily Briefing — 31 May 2026

Price Profile #

Std dev €24.9/MWh · Median €126.9/MWh · Periods above €150: 10 of 48 (21%)

Sunday, a near-scarcity event without quite breaking €200. Mean €136.99, peak €196.68 at 18:30, range €82.68. The evening peak built sharply but topped just below the scarcity threshold — three periods cleared €193–197 but none crossed €200.

Periods 1–2 (€140, €137 at 23:00–23:30 with wind at 52%) look real this time — Saturday’s tail faded to €141 at 22:30, and the €140 at 23:00 fits the trend. The wind boundary glitch is in period 3 only (54% → 36%).

Overnight ran €123–140 from 01:00 to 06:30. Morning ramp barely existed — €117 at 06:00 → €121 at 07:00 to 09:30 (flat), no morning peak. Wind held 22–28% through the working day (relatively low) but Sunday’s softened demand kept midday prices contained at €114–130 from 10:00 to 16:00, with the floor at €114.00 at 14:30.

Then the evening built: €117 at 15:00 → €131 at 16:30 → €165 at 18:00 → €197 at 18:30 (one-period spike), holding €185–195 across 19:00–21:00 before fading to €155 at 22:30.

10 of 48 periods cleared above €150; 0 above €200. Near-miss scarcity.

Price vs Wind #

Mean wind: 32.3% · Range: 21.6%–52.4%

V-into-evening wind shape, modest depth. Wind held 35–52% overnight (peak at 04:00–05:30), drained through the morning to 24% by 06:30, held 22–28% through the working day (the day’s lowest sustained wind window), and then drifted back up through the evening — 30% at 18:30, 38% at 21:00, 47% by 22:30.

The evening recovery is what kept this off the scarcity board. From 18:30 (the €197 peak), wind climbed from 32% to 41% over the next 2 hours. That recovery is what capped the peak at €197 rather than letting it climb through €200 like May 29’s evening did. Wind recovery during a peak window is the difference between a near-scarcity day and a scarcity day.

Compare to May 29: same V-into-evening shape, similar wind levels, but May 29’s wind kept falling (35% → 14%) while May 31’s wind started recovering (32% → 41%). Net result: May 29’s evening cleared €200+ for 3 periods; May 31’s evening cleared at €197 but never crossed.

Week in Context #

Three weekend days (May 30, 31, June 1) bookending the wind-shape variance week. Sunday’s near-miss is the bridge: the wind shape was right for scarcity but the wind recovery saved the merit order from climbing into peakers.

Price Duration Curve #

Periods above €150: 10 (21% of day) · Above €200: 0 (0% of day)

The PDC has a sharp single-peak top (1 period at €197) followed by a smooth descending shelf through the evening cluster (9 more periods €152–195) and a long gradual mid-section through the working-day prices. No real flat trough — the cheapest 4 periods averaged €115.

The shape signals “shaped day, no scarcity.” A real evening peak that’s worth capturing but doesn’t break into peakers. From a BESS perspective, a clean spread-capture day in the wider €80 range.

Price Spread #

Captured spread: €76/MWh · Charge: €117/MWh (14:00) · Discharge: €193/MWh (19:30)

BESS Dispatch Signal #

Simulated 1MW/2MWh battery, one optimal DAM cycle. Gross before network charges and capacity costs.

€95 gross — solid mid-range Sunday. Charge €117 in the midday trough (14:00–15:30 at €117 avg), discharge €193 in the evening peak (19:30–21:00 at €193 avg). Captured spread €76, ROI 40.7% on the €233 charge cost.

The dispatch picked the evening cleanly — the morning had no peak to compete with. The captured spread €76 is reasonable; what matters analytically is that the spread failed to enter top-tier territory because the evening peak failed to break €200. One more percentage point of wind drainage during the 18:00–19:00 window and today would have been a top-5 day at ~€130 gross. The threshold for top-tier BESS revenue sits around the €200 line — and today missed it by €3.

28-day BESS series: cumulative €2,852, mean €102/day.

Commentary #

Sunday, a near-scarcity event with the evening peak topping at €196.68 — three euros short of the scarcity threshold. Wind held 22–28% through the working day (the day’s lowest sustained wind window), but recovered through the evening from 30% to 47% as the peak built. That recovery was the difference between a near-miss and a top-5 BESS day. Compare to May 29: same V-into-evening wind shape, similar wind levels, but May 29’s wind kept falling while May 31’s wind started climbing — and May 29 cleared €203, May 31 cleared €197.

The structural reading: there’s a discontinuous reward function at the €200/MWh threshold. Peakers price in at €200+; gas at high load prices at €175–195. The merit order doesn’t smoothly climb through €200 — it steps into peaker bids. A day that climbs to €197 and stops looks similar to a day that climbs to €203 in everyday statistics; for BESS revenue they differ by ~€30–40 gross on a single cycle. Forecasting the scarcity threshold (binary) matters more than forecasting the peak price (continuous).

For storage, €95 gross — solid Sunday in the mid-range, captured spread €76. 28-day cumulative €2,852, mean €102/day. The day failed to break into top-tier BESS revenue by 3 euros on the discharge price. Top-tier BESS days are scarcity days; near-miss days are mid-range days; the binary distinction is the €200 threshold. That’s the structural rule emerging from the data — a useful one for any operator modelling BESS revenue distributions.