A comparison of day-ahead electricity prices across Europe for the whole of 2025 reveals a clear and persistent pattern: electricity prices in Bulgaria paid by non-household users are most often above the EU average, with deviations becoming especially pronounced during periods of system stress and, occasionally, during periods of oversupply.
Evidence of the latter occurred on 1st May 2025, when Bulgaria experienced deeply negative prices (around –100 EUR/MWh) during the middle of the day – almost twice as negative as the EU average. This coincided with very high renewable generation (notably peak solar output), low holiday demand, and limited system flexibility. Similar price dynamics were observed across Europe on that sunny spring day. Negative prices in such cases are not a sign of market failure, but rather an indication of insufficient flexibility and interconnection – limited storage capacity, constrained export possibilities, and inflexible generation units that cannot easily ramp down output.
At the opposite end of the spectrum, the highest price of the year (603.3 EUR/MWh) was recorded on 20 January 2025 at 17 h, during the evening peak of a winter day. This reflects the combined effect of high demand, low solar output, and tight regional supply, when the marginal generation unit becomes expensive and cross-border imports are constrained.
When prices are aggregated seasonally, Bulgaria shows a consistent premium over the EU average in all four seasons. Even in summer – despite long daylight hours and high solar production – prices remained on average around 17% higher than the EU level, with the gap widening significantly in winter. This seasonal pattern suggests that price differences are driven less by short-term volatility and more by structural factors, such as limited interconnection capacity with lower-price regions, a fuel mix that remains sensitive to fossil fuel price dynamics, and a lower availability of flexible resources during peak demand periods.
Importantly, Bulgaria is not an outlier within its region. Greece and Romania display similar seasonal price patterns, both in absolute price levels and in their deviations from the EU average. This points to common characteristics of South-East European power markets – partial market integration, congestion on key cross-border connections, and limited access to the hydro-rich and liquid power systems of Northern Europe, where large reservoir hydro, deep market liquidity, mature demand response, and dense interconnection significantly dampen price volatility.
By contrast, Nordic countries such as Sweden consistently record the lowest prices, benefiting from abundant hydro resources, strong interconnections, and high system flexibility. Italy, on the other hand, often exhibits the highest prices, reflecting geographic constraints and a greater reliance on higher-cost marginal generation.
Ultimately, closing the price gap for Bulgaria and much of South-East Europe is less about short-term interventions and more about structural change: deeper market integration, increased interconnection capacity, and sustained investments in flexibility, including storage, demand response, and dispatchable low-carbon generation.
Author: PhD Candidate Lyubimka Georgieva
Data source: ENTSO-E Transparency Platform (Day-Ahead Market, Energy Prices)
All aggregations and comparisons performed in Python
Visualisations created in Canva