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Bulgaria’s abundant energy storage capacity is turning it into a regional hub. The country can import electricity at low, zero or negative prices even when its own domestic production exceeds demand, and then export it back when prices rise in the evening. The business case for battery energy storage systems (BESS) is strong, given the increasing frequency and depth of negative prices, together with extreme daily spreads.
Total battery system capability in Bulgaria amounts to more than 2 GW, and with almost 8 GWh in storage capacity, it can power the entire country for two hours, Kapital reported. In the afternoon on April 29, a relatively cloudy day, the country produced more electricity than it consumed, but still imported a substantial quantity.
Bulgaria is benefiting from a stellar expansion of its battery storage market, which is by far the strongest in Europe relative to the size of the economy and population. The phenomenon was mostly enabled via the European Union by the RESTORE support scheme. In addition, the government is counting on vast pumped storage hydropower capacity.
Operational battery energy storage systems may hit 3.5 GW by the end of the year. After that, growth could slow as spreads between the highest and lowest prices of the day tighten and limit income from energy storage.
BESS operators in Bulgaria profiting from solar power peaks
Neighboring Greece has suffered extensive delays. Analysts expect its portfolio to reach 1 GW in 2026. In the meantime, storage operators in Bulgaria are getting a windfall from the shift in the conjuncture of power supply and demand. The biggest factor is solar power, as investing in the segment without involving storage is causing a surge in losses.
According to the Electricity System Operator (ESO), power generation was at 4.82 GW at 15:55 on the said day, versus 4.09 GW on the consumption side. At the same time, 1.67 GW was charging energy storage systems as they were absorbing the entire surplus as well as receiving electricity from neighboring countries.
Price spread against Greece was EUR 44.33 per MWh
The snapshot with data from the transmission system operator (TSO) indicates that batteries are reshaping the electricity market in the Balkans, the article adds. The country can import cheaply or at zero and negative prices, and use the stored power when prices rise, lowering the costs for consumers.
Namely, during the responding 15-minute interval through 16:00, the day-ahead market price for Bulgaria was EUR 44.34 per MWh, compared to just EUR 0.01 per MWh in Greece. The planned flow was 879 MW from Greece to Bulgaria.
Batteries are becoming like a large flexible consumer, the media outlet pointed out. Some of the stored energy was even returned to Greece later, but much more went to Romania.
May 1 power prices tested limit down at nearly EUR 500 per MWh below zero
Of note, charging a battery is profitable only when the spread is higher than a facility’s operating costs. The business case is still strong, especially with extreme swings on sunny weekends and holidays in spring and autumn, when the demand for heating and cooling is low.
Hungary, Greece, Bulgaria and Romania are often among the world’s top ten countries with their domestic shares of daily photovoltaic output.
In much of Europe, day-ahead levels for the May 1 holiday went nearly to EUR 500 per MWh under zero, which is the price floor. Germany was at EUR 499.99 per MWh in negative territory, resulting in a spread of more than EUR 700 per MWh versus the evening peak!
Then the May 1 intraday price plunged to an all-time low of EUR 855.24 per MWh under zero, Montel reported, and the daily spread was almost EUR 1,100 per MWh. The intraday price is allowed to sink to EUR 9,999 per MWh in negative territory.
The day-ahead market at the Hungarian HUPX power exchange was at limit down for two and a half hours, at EUR 500 per MWh under zero.
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