Electricity trading across South-East Europe is fundamentally shaped by cross-border flows that redistribute generation surpluses and deficits between interconnected markets. These flows form the backbone of regional electricity trading, enabling market participants to exploit price differences between neighbouring countries while simultaneously ensuring system stability across a geographically diverse power network.
Recent trading data reveal several dominant electricity corridors connecting Central Europe, the Balkans and the Mediterranean. Among the most important is the corridor linking Romania and Hungary. Romania possesses a large and diversified generation fleet that includes nuclear power from the Cernavodă plant, extensive hydropower along the Danube, and a growing portfolio of renewable energy projects. When Romanian generation exceeds domestic demand, electricity frequently flows northward toward Hungary, where it can be redistributed further across Central Europe or exported southward into the Balkans.
Hungary occupies a strategic position within this network. Acting as a central redistribution hub, Hungary receives electricity from Austria, Slovakia and Romania and then transmits part of that energy toward Serbia and Croatia. Power flows from Hungary to Serbia are particularly significant because Serbia’s electricity system still relies heavily on lignite-fired generation, which is often less flexible than the hydropower or nuclear generation available in neighbouring markets. When demand rises or domestic generation is constrained, Serbia frequently imports electricity through this corridor.
Another major trading pathway connects Slovenia and Italy. Slovenia’s power exchange BSP SouthPool is closely linked with the Italian market, allowing electricity generated in Central Europe to reach the Mediterranean through Slovenian transmission lines. Because Italian electricity prices are often higher than those in Central Europe, traders frequently export power through this corridor whenever transmission capacity allows.
Further south, electricity flows between Bulgaria and Greece play a crucial role in balancing the Eastern Mediterranean electricity system. Bulgaria’s coal- and nuclear-based generation fleet often produces surplus electricity during periods of moderate demand. These surpluses can be exported to Greece, particularly during summer months when air-conditioning demand drives Greek electricity consumption sharply higher.
Commercial flow data illustrate the magnitude of these cross-border exchanges. Average flows from Romania to Hungary have recently reached approximately 770 megawatts, while flows from Hungary toward Serbia often exceed 600 megawatts during high-demand periods. Electricity exports from Greece to Italy through the Adriatic interconnection have averaged close to 700 megawatts, reflecting Italy’s role as one of Europe’s largest electricity importers.
The existence of these corridors enables electricity traders to pursue arbitrage opportunities between markets. Arbitrage occurs when electricity can be purchased in a lower-priced market and simultaneously sold in a higher-priced market. The profitability of such trades depends on both the price difference between markets and the availability of cross-border transmission capacity.
For example, if electricity prices on the Romanian OPCOM exchange fall significantly below those on the Hungarian HUPX market, traders may schedule exports from Romania to Hungary. As electricity flows across the border, supply in Hungary increases while supply in Romania decreases, gradually reducing the price difference between the two markets. In this way, cross-border trading not only generates profits for traders but also promotes more efficient price formation across the entire regional electricity system.
Transmission constraints occasionally limit these arbitrage opportunities. When interconnectors reach their maximum capacity, additional electricity cannot flow between markets even if price differences remain significant. These constraints create localized price divergences that traders monitor closely. Identifying which borders are likely to become congested during specific hours is a critical component of successful electricity trading strategies.
The Balkan region’s growing renewable energy capacity is further increasing the importance of cross-border electricity flows. Solar and wind generation are inherently variable, producing electricity only when weather conditions permit. When solar output surges in one country, excess electricity may be exported to neighbouring markets where demand remains strong. Conversely, when renewable production declines, imports from other countries help compensate for the shortfall.
Hydropower also plays an important role in shaping regional electricity flows. Many Balkan countries possess large hydropower reservoirs capable of adjusting generation levels quickly. During periods of high electricity prices, hydro operators may increase generation and export electricity to neighbouring markets. During low-price periods, they may reduce generation and conserve water for future use. This flexibility allows hydropower plants to act as both generators and energy storage systems within the regional electricity network.
As electricity markets across South-East Europe continue to integrate, cross-border flows are likely to grow even further. Several new transmission projects are currently under development, including high-voltage interconnections linking Serbia with Romania, Bosnia and Herzegovina with Croatia, and Greece with Bulgaria. These projects aim to expand cross-border transfer capacity and enable greater participation of Balkan markets in the broader European electricity trading system.
In this evolving landscape, electricity trading strategies will increasingly depend on understanding the structure of regional power flows. Traders who can anticipate congestion patterns, renewable generation fluctuations and demand shifts will be best positioned to exploit arbitrage opportunities across the Balkan electricity network. The region’s complex geography and diverse generation mix ensure that cross-border electricity trading will remain one of the defining features of South-East European power markets for years to come.