ACER asks Greek authorities to probe power market for manipulation

The European Union Agency for the Cooperation of Energy Regulators (ACER) is warning of signs of manipulation in Greece’s day-ahead electricity market (DAM) registered during the summer of 2024.

The region of Southeastern Europe experienced several months of high electricity prices, with average monthly levels close to EUR 200 per MWh in the case of Greece.

ACER used data from the Hellenic Energy Exchange (HEnEx) to calculate the hourly day-ahead demand and supply curves for the Greek bidding zone in the said period.

It included 93 observations, meaning 93 pairs of demand and supply curves, from June 15 to September 15 of last year.

Based on the above, four scenarios were formed, simulating and analyzing market conditions on different days and times. The baseline included all the cases and the clearing price was always above EUR 100 per MWh.

The so-called stressed scenario involved 17 observations, when prices climbed close to EUR 500 per MWh, and the critical scenario had two observations, with prices of EUR 900 per MWh.

There was even an extreme scenario,  covering September 4, when at 20:00 the price reached its maximum, with EUR 942 per MWh.

650 MWh would have made enormous difference

ACER noted that if an extra 650 MWh of energy were available during that hour, it would have reduced the price by a huge EUR 630 per MWh to EUR 311 per MWh.

The extra power could have arrived either internally from peak power plants, or through interconnections with neighboring countries.

The result is similar for the stressed scenario – 420 per MWh lower, and the baseline, when the level would have come in at 100 per MWh down from the actual prices.

Capacity withholding as a possible cause

The regulator added that during times of pressure in the system, the market power of producers became much more pronounced and their bidding behavior changed.

Based on the above, ACER reaches two conclusions. One, interconnections in the region must be utilized based on the 70% European rule to bring prices down.

Secondly, Greek authorities need to initiate a probe into whether market power was used to manipulate or abuse dominant positions, for example in the form of capacity withholding.

ACER also said data from HEnEx and the Regulatory Authority for Energy, Waste and Water (RAAEY or RAEWW) are incomplete and that more transparency is necessary moving forward.