Cross-border electricity trading in Southeast Europe fell sharply in the week to September 13, reducing the region’s ability to balance supply and demand between national markets. The decline coincided with higher wholesale prices in most countries. Aggregate net electricity flows dropped 23.2% week on week to 0.94 TWh, from 1.22 TWh in the previous period.
The reduction in cross-border activity occurred alongside a 7% decrease in wind and solar generation and lower thermal output in Greece, Serbia, Croatia and Türkiye. These generation changes affected the cross-border balance between neighbouring systems during the same weekly window.
Country-by-country import and export changes
Romania recorded the largest fall in net imports, which declined by almost 50% to 74.54 GWh. The decrease was supported by an almost 80% increase in wind generation and a 10.6% rise in thermal output, lowering reliance on electricity from neighbouring markets.
Hungary reduced its net imports by 12.5%, while Croatia recorded a 9.7% decline. Despite lower import volumes, wholesale prices rose: Croatia’s weekly average price increased 8.5% to €176.34/MWh, and Hungary’s rose 4.6% to €177.31/MWh.
Bulgaria moved against the regional trend, with net exports increasing by 38% to 274.67 GWh. Higher thermal generation, together with a modest increase in variable renewable output, enabled Bulgaria to supply neighbouring markets despite a significant decline in hydropower generation.
Greece increased its net export position, with exports rising from 79.2 GWh to 91.93 GWh. The change was driven primarily by a 7.5% decline in domestic electricity demand, which reduced the amount of generation required to meet consumption within the country.
Serbia recorded a marginal increase in exports as higher hydropower generation and weaker domestic consumption offset lower thermal output. Even so, the Serbian wholesale electricity price increased by 11.1%, representing the strongest weekly price rise among the monitored Southeast European markets.
Interconnector role amid weaker renewables
The decline in cross-border trading points to the role of regional interconnectors linking the Western Balkans with Greece, Bulgaria, Romania, Hungary and Croatia. When renewable generation declines across multiple markets at the same time, available transmission capacity becomes more important for regional supply-demand balancing.
The lower level of cross-border flows can leave individual markets more exposed to domestic generation costs. It can also contribute to wider price differences between neighbouring countries when renewable output is volatile and conventional generation remains constrained.
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