I-SEM Daily Briefing — 8 May 2026

Price Profile #

Std dev €21.31/MWh · Median €159.43/MWh · Periods above €150: 35 of 48 (73%)

Week in Context #

Price Duration Curve #

Periods above €150: 35 (73% of day) · Above €200: 5 (10% of day)

Peak / Off-Peak Spread #

Peak avg (07:00–22:00): €168.6/MWh · Off-peak avg: €155.98/MWh · Spread: €12.62/MWh

BESS Dispatch Signal #

Updated 2026-08-27: the BESS simulation previously allowed the discharge window to occur before the charge window ended, which is physically impossible for a battery. Recalculated enforcing charge-before-discharge — see below.

No profitable single-cycle trade today. The day’s cheapest four-period block sits at 21:00 (€140/MWh avg) — the late-evening fade. But the day’s priciest block, €211/MWh, falls at 07:00, earlier in the same delivery day. A battery can’t discharge into a peak that already happened before it charged, so with only one cycle allowed per day, there’s no causally valid pairing left: by the time the evening trough opens up, the morning’s opportunity is already behind it.

Commentary #

Friday softened. Mean dropped to €163.87/MWh — the lowest of the working week — and the signature of the day was the evening that never arrived. Price peaked at €216 at 07:30 and then decayed: through the afternoon, through the evening, reaching a daily minimum of €127.34 at 22:30. Every other weekday this run produced an evening peak above €200. Friday’s topped at €168.

The morning ramp held, as it has every working day this week. 06:00 to 07:30 moved €66/MWh — slightly softer than the €80+ ramps of Tue–Thu, but the same thermal signature in the same window. One exception worth flagging: a single spike to €205 at 11:00, €50 above its neighbours on either side. A single half-hour jumping that far above its neighbourhood is an operational event — a forecast error, short outage, or interconnector swing — the kind of thing visible next day in EirGrid’s system reports.

For storage, no trade today — the run’s first no-cycle day. The day’s real opportunity (charge into the evening fade, discharge into the morning peak) needs a cycle that spans two calendar days, which a same-day model can’t take. It’s a reminder that the single-cycle model understates real BESS revenue on exactly the days when the shape is this lopsided: a rolling 24-hour optimiser would have captured this one.

For the week-level picture and what it means if you're buying, see Weekly Analysis — 10–16 August 2026.