Hydropower generation moved in sharply different directions across Southeast Europe in the week to September 13, strengthening electricity supply in Croatia and Serbia while increasing pressure on power systems in Bulgaria and Greece.
Regional hydropower output declined 2.1% to 2.81 TWh, but the relatively small overall change masked significant differences between individual markets.
Croatia recorded the largest increase in hydropower generation, with output rising 53.7%. The additional production provided important support as wind and solar generation fell 24.3% and thermal output declined 17.6%. Without the stronger hydro contribution, Croatia would likely have faced greater reliance on electricity imports.
Despite the increase in hydropower, Croatia’s wholesale electricity price rose 8.5% to €176.34/MWh. Lower wind and solar generation, weaker thermal output, reduced imports and tight conditions in neighbouring markets outweighed the improvement in domestic hydro availability.
Serbia also recorded a significant increase in hydropower generation, with output rising 18.2%. Combined with lower electricity demand, the additional hydro generation enabled Serbia to maintain a marginal net export position despite a 5.1% decline in thermal production. The Serbian wholesale price nevertheless increased 11.1% to €155.70/MWh.
Bulgaria experienced a much weaker hydro position. Hydropower generation fell 27.4%, the largest decline among the monitored markets. The country compensated through a 17.6% increase in thermal generation and slightly higher wind and solar output, allowing net exports to increase 38%.
Greece also recorded a decline in hydropower production, down 11.2% to 58.95 GWh. The reduction came alongside weaker renewable and gas-fired generation. However, a substantial fall in domestic electricity demand allowed Greece to reduce its wholesale price while increasing exports.
Romania recorded a 2.5% increase in hydropower generation, complementing a strong rise in wind output and higher thermal production. The combination of stronger domestic generation sources enabled Romania to reduce its net imports by almost half.
Hydropower remains one of Southeast Europe’s most important flexible generation resources, allowing producers to respond relatively quickly to changes in electricity prices and renewable output. Its value becomes particularly significant when solar generation declines during evening hours or wind production changes unexpectedly.
Week 37 demonstrated that stronger hydropower availability can improve national electricity balances, but cannot fully shield individual markets from regional scarcity, weaker renewable output and cross-border transmission constraints.
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