Bulgaria’s electricity sector reached a historic milestone in 2025, as renewable energy sources became the country’s second-largest producer of electricity, surpassed only by nuclear power. For the first time, combined generation from solar, wind, hydropower, biomass, and waste exceeded output from coal-fired plants, signaling that the energy transition has moved from concept to reality.
Data from the Electricity System Operator (ESO) shows that this shift was largely driven by the rapid expansion of solar capacity and the growing role of battery storage, which has extended the usable hours of photovoltaic production. Meanwhile, coal-based generation fell further compared with 2024, reaching the lowest levels ever recorded in Bulgaria.
Bulgaria remains a net electricity exporter, but only marginally. Net exports totaled 1,268 GWh, nearly six times lower than in the exceptionally strong export year of 2022, highlighting a changing regional role. Coal generation has declined steeply since 2023, with output in 2025 about 60% lower than in 2022, surpassing targets under the Recovery and Resilience Plan, which aimed for a 40% reduction compared with 2019. The actual reduction now stands at nearly 49%.
Pressure on coal plants is expected to intensify in 2026, when the contract for the second US-owned plant, AES Galabovo, expires. High carbon allowance prices, hovering around €85/ton, have made coal generators less competitive. As a result, the state-owned TPP Maritsa East 2 increasingly relies on supplying regulated household consumption through a new exchange-based purchasing model, even as it continues to operate at a loss. Despite these challenges, coal is likely to remain Bulgaria’s third-largest electricity source for several years, largely due to the limited role of natural gas in power generation. The key question is whether mining and generation can be optimized enough to remain viable under the new market and climate conditions.
In contrast, solar power has entered a rapid expansion phase. Roughly two-thirds of Bulgaria’s more than 4.5 GW of installed solar capacity was added in the past three years. Improved panel efficiency and battery systems have quadrupled solar output compared with 2022. By 2025, solar alone was generating roughly two-thirds of the electricity produced by coal-fired plants, and if trends continue, it could surpass 80% of coal generation as early as 2026. This year is also expected to see record battery storage installations, helping to absorb more solar electricity, smooth price fluctuations, and reduce zero or negative prices during the day.
Wind energy, however, faces delays. New investments have stalled due to lengthy administrative and environmental approvals, often taking three to five years. This is critical because wind generation typically peaks at night and in winter, complementing solar output. The first new wind farms, each with capacities of 70–100 MW, are not expected before the end of 2027.
Bulgaria’s regional role is also evolving. Rather than acting primarily as a major exporter, the country increasingly functions as a balancing hub. ENTSO-E data shows that Bulgaria has become a consistent net importer of electricity from Greece and Turkey, where the energy transition has progressed faster. Greece, in particular, has rapidly expanded renewables and replaced much of its coal generation with gas.
Looking ahead, Bulgaria could emerge as a key flexibility provider in southeastern Europe. With the expansion of battery storage and planned new pump-storage hydropower projects, the country has the potential to act as a large-scale energy buffer, a role that could offer both commercial and strategic advantages in the region’s evolving energy landscape.