Cross-border electricity trading in Southeast Europe fell sharply in the week to September 13, affecting the region’s ability to balance national supply deficits. The decline also contributed to higher wholesale prices across most markets. Aggregate net flows decreased 23.2% week on week to 0.94 TWh, down from 1.22 TWh in the previous period.
The contraction coincided with a 7% fall in wind and solar generation. It also reflected lower thermal production in Greece, Serbia, Croatia and Türkiye. These changes occurred alongside reduced cross-border volumes across the interconnected systems.
Net flow changes among regional importers
Romania recorded the largest shift among regional importers, with net imports falling almost 50% to 74.54 GWh. The change was supported by an almost 80% increase in wind generation and a 10.6% rise in thermal output. Hungary reduced net imports by 12.5%, while Croatia recorded a 9.7% decline.
Croatia’s lower imports did not necessarily indicate looser national conditions, according to the reported price movements. Croatia’s electricity price rose by 8.5% to €176.34/MWh, while Hungary’s increased by 4.6% to €177.31/MWh. Reduced cross-border access left both systems more dependent on domestic generation during periods of weaker renewable output.
Bulgaria, Greece and Serbia shift toward exports
Bulgaria moved in the opposite direction, increasing net exports by 38% to 274.67 GWh. Higher thermal production and a modest increase in variable renewable generation enabled Bulgaria to supply neighbouring markets despite a steep reduction in domestic hydropower.
Greece strengthened its net export position as exports rose from 79.2 GWh to 91.93 GWh. The reported shift was supported less by stronger production than by a 7.5% decline in domestic demand, which released electricity for neighbouring systems.
Serbia recorded a marginal increase in exports as higher hydropower and weaker consumption offset lower thermal generation. Even so, the Serbian price rose by 11.1%, the strongest increase in the region, based on the figures provided.
Interconnector role as renewable output declines together
The reduction in trading highlighted the commercial value of interconnectors linking the Western Balkans with Greece, Bulgaria, Romania, Hungary and Croatia. When renewable production falls simultaneously across several markets, available transmission capacity becomes part of the regional supply stack . Restricted flows leave national systems more exposed to domestic generation costs and produce wider, more persistent price differences .
