Regional market coupling aligned much of Hungary, Romania, Slovenia, Croatia, Serbia and Albania around €150/MWh on 11 August. However, the fifteen-minute price curves for 12 August show that this convergence becomes significantly weaker when markets are examined at the interval level.
Hungary reached almost €265/MWh, Romania surged to €310/MWh and Bulgaria approached €199/MWh. The divergence suggests that available cross-border transmission capacity was insufficient to fully equalise evening scarcity prices, highlighting the limitations of regional coupling during periods of tight supply.
Romania’s emergency measures also weaken the assumption that purchased transmission capacity automatically guarantees physical delivery. During an adequacy event, transmission system operators can restrict commercial exchanges in order to protect system security, creating additional risks for cross-border market participants.
The Montenegro–Italy corridor has a different value profile. Recent daily auction prices in the export direction averaged approximately €8.59/MWh, supported by Italy’s persistent price premium over Adriatic markets. However, Montenegro’s own dry-summer electricity deficit can limit export availability even when Italian prices remain significantly higher.
The submarine interconnector can therefore serve two opposing functions: supporting Montenegro with imports during periods of domestic scarcity while providing access to the Italian market when EPCG has surplus hydropower or wind generation. Its economic value consequently lies in optionality rather than a permanently fixed direction of flow.
Intraday coupling reliability has also become an increasingly important factor in power-price formation. Repeated cancellations and partial decoupling of European intraday auctions during early August reduced traders’ ability to correct cross-border positions. This becomes particularly significant when fifteen-minute prices can move from zero to €300/MWh within a few hours.
A portfolio relying on forecast solar generation but lacking a dependable intraday trading route can therefore face balancing costs that significantly exceed the revenue captured through the original day-ahead transaction. Storage can reduce physical imbalance exposure, but it cannot fully compensate for an unavailable or illiquid market interface.
The broader implication is that regional market integration does not eliminate price risk. As renewable penetration increases and intraday price spreads widen, transmission availability, market coupling reliability and flexibility resources will become increasingly important determinants of the actual value of cross-border electricity trading.
