In South East Europe, cross-border electricity flows can influence prices as strongly as generation costs. A system may show sufficient installed capacity, yet still experience high prices when imports cannot physically arrive when needed. At the same time, domestic tightness can be eased quickly if interconnector capacity is available and imports are secured.
ACER’s 2026 monitoring report on Southeast Europe, focusing on 2024 price spikes, pointed to a structural need for greater cross-zonal capacity and system flexibility. The analysis linked regional stress not only to expensive generation, but also to limited flexibility after evening solar output decline. It also cited restricted access to lower-priced electricity from neighboring markets.
This assessment indicates that some SEE price spikes were tied to constraints on cross-border electricity movement. The report frames regional electricity price dynamics as closely connected to transmission conditions. In this context, the region’s main flow corridors are described as key determinants of market behavior.
Main SEE flow corridors and their market role
The first corridor runs from Central Europe into South East Europe, passing through Hungary, Slovenia, Croatia, and Romania toward the Balkans and Greece. When Central Europe is structurally long on power and SEE is short, the corridor acts as a stabilizer for prices. When transmission capacity is constrained, markets decouple and price divergence increases sharply.
The second corridor is the Hungary–Romania–Bulgaria–Greece axis, described as a major north–south structure in the region. It connects Central European liquidity with Romania’s hydro, wind, solar, and nuclear mix. It also links Bulgaria’s nuclear, coal, and rapidly expanding solar and storage capacity with Greece’s gas generation, solar output, and peak summer demand profile.
The third corridor is the Western Balkan loop, spanning Serbia, Bosnia and Herzegovina, Montenegro, Albania, Kosovo, and North Macedonia. The trading area is characterized as weather-sensitive and policy-sensitive. Hydro conditions, coal availability, Serbian exchange liquidity, and explicit capacity allocation mechanisms are cited as factors that can shift regional balances quickly and drive localized volatility.
The fourth corridor covers the Adriatic–Italy connection. Italy is described as often operating with distinct price behavior compared with the Balkans, which can create arbitrage opportunities via interconnectors linking Greece, Montenegro, Slovenia, and Croatia. The source also notes that these flows depend on available capacity and face route and congestion risk.
The fifth corridor concerns Ukraine-related eastern flows following Ukraine’s synchronization with the continental European grid. Flows involving Romania, Hungary, Slovakia, and neighboring systems are described as increasingly relevant for regional balancing and SEE price formation signals.
Regulation-driven changes in EU–Western Balkans commercial flows
Cross-border electricity flows are also influenced by carbon policy and trade regulation. In Q1 2026, the Energy Community reported a 25% decline in commercially scheduled EU–Western Balkans exchanges. It also reported that average day-ahead prices in Contracting Parties were approximately €30/MWh lower than in adjacent EU markets.
The Secretariat attributed the divergence to CBAM-related costs, origin tracking requirements, and regulatory uncertainty affecting commercial flow decisions. Under normal market conditions, lower prices in the Western Balkans would be expected to encourage exports toward higher-priced EU markets. If such exports do not occur, the constraint is described as no longer purely price-based.
The source describes a situation where physical flows, scheduled commercial flows, and economic price signals can diverge. A trader may observe a clear price spread but still be unable to execute profitably due to CBAM exposure or explicit capacity costs. It also cites nomination complexity and uncertainty around cross-border eligibility rules.
Five-layer framework for analyzing cross-border power movements
For market participants, cross-border analysis is presented as operating across five layers. The first layer is physical capacity: what can physically flow through the grid at any given time. The second layer is commercial capacity: what transmission rights are available through auctions or allocations.
The third layer concerns market design, including whether borders are coupled or explicitly managed. The fourth layer covers regulatory framework elements such as CBAM, REMIT, licensing, and scheduling rules. The fifth layer addresses portfolio and risk structure across jurisdictions, including imbalance handling, collateral needs, and settlement exposure.
For policymakers in South East Europe, the source links needs beyond generation to cross-border transmission usability. It cites requirements including improved coordination of outages, deeper market coupling, and more dynamic grid utilization alongside additional transmission capacity. It also describes how these factors relate to price formation at borders.
In South East Europe, the border is described as effectively defining the market outcome. Price spreads are identified as the primary signal while transmission rights are characterized as a key tradable asset. The ability to move electricity safely under applicable rules remains central to competitive positioning across jurisdictions.
