I analyzed yesterday’s French balancing market: a 324.8 €/MWh night spike, an 11.4 €/MWh midday low, and another evening ramp

Yesterday’s French balancing market in RTE showed a pretty clear real-time stress pattern.

The intraday UPWAP ranged from 11.4 €/MWh at 11:30 to 324.8 €/MWh at 01:30, with another strong rise in the evening above 220 €/MWh.

After going through the imbalance data, activation volumes, generation mix, wind forecast data and unit unavailability, the day seems to break down into 4 distinct phases:

1) Main night spike at 01:30 — 324.8 €/MWh

This was the most interesting move of the day because demand was not especially high at that time: French load was around 47.2 GW.

What stands out is the combination of:

France already importing very heavily: -14.3 GW

actual wind below intraday forecast: 2.50 GW actual vs 2.78 GW forecast

a sharp hydro drop just before the spike: from 10.6 GW at 01:00 to 9.4 GW at 01:30

clear upward reserve activation: 308 MW aFRR upward, plus 55 MW RR upward

The system imbalance was -45.4 MWh and the balancing direction was upward.

So even in the middle of the night, the system seems to have briefly lacked flexibility, and the balancing price jumped accordingly.

2) Morning tension from 06:00 to 07:45

This was less of a sudden shock and more of a structural stress period.

At 06:00, load was 43.4 GW, solar was still 0 GW, France was importing -14.4 GW, and the upward balancing price was already 134.3 €/MWh.

By 07:45, load had risen to 46.3 GW, and the upward balancing price was still 149.0 €/MWh.

There was continued reserve use during this window, including:

87 MW mFRR upward

125 MW RR upward

This looks like a classic morning ramp with limited margin in the system.

3) Midday collapse at 11:30 — 11.4 €/MWh

This is the easiest part of the day to explain.

At 11:30:

balancing price fell to 11.4 €/MWh

system imbalance was +212.5 MWh

balancing direction turned downward

solar output had climbed to 9.34 GW

load was 49.8 GW

On the balancing side, RTE was clearly absorbing surplus energy:

139.6 MW aFRR downward

16.7 MW RR downward

So this part looks like a straightforward case of strong solar pushing the system into surplus and crushing the balancing price.

4) Evening ramp from 18:00 to 18:45

This was probably the clearest example of renewable-

driven stress during the day.

Between 18:00 and 18:45:

load rose from 47.3 GW to 50.6 GW (+3.23 GW)

solar dropped from 1.45 GW to 0.31 GW (-1.14 GW)

hydro ramped from 9.5 GW to 12.8 GW (+3.29 GW)

upward balancing price rose from 156.4 €/MWh to 226.3 €/MWh

At the same time, wind was still well below the intraday forecast:

18:00: 1.88 GW actual vs 2.49 GW forecast

18:45: 2.21 GW actual vs 3.23 GW forecast

So the evening story looks pretty clean: rising demand, collapsing solar, underperforming wind, and hydro having to ramp hard to keep the system balanced.

The strongest signal in the data is probably the wind forecast error.

Actual wind generation was below the intraday forecast during 86 of 92 quarter-hours available in the forecast file, with an average shortfall of about 447 MW.

To me, this day looked less like a random price event and more like the balancing market pricing the scarcity of grid flexibility in real time.

Curious how others here would interpret the 01:30 spike in particular, because that one is the least intuitive at first glance.