Bulgaria is asserting its position on the European energy map through a strategic decision to increase its current electrical interconnection capacity from 4 GW to 10 GW by 2030. The move, recently announced by transmission system operator (TSO) ESO, aims to reinforce the national grid to facilitate the integration of renewable energy—particularly solar and wind—while ensuring greater system stability and strengthening regional integration.

The investment programme is already underway. By the end of 2024, the country will have connected 4,500 MW of new capacity—mostly renewable—to the national power system. A key milestone has been the commissioning of an interconnection with Greece, via a 400 kV line with 2 GW capacity, operational since July 2023. This link not only enhances electricity exchange between the two countries but also marks a major step towards a more interconnected grid across Southeast Europe.

The strategy goes beyond the physical development of infrastructure. Bulgaria has made significant progress in modernising and digitalising its power system. Through its integration into PICASSO, the European platform for automatic frequency restoration reserves (aFRR), ESO has become the first TSO in Southeast Europe to participate. This integration gives Bulgaria access to a shared pool of energy reserves, resulting in greater operational flexibility and system management efficiency, particularly as intermittent sources like wind and solar increasingly dominate the energy matrix.

However, the path forward is not without challenges. An analysis by the Bulgarian Wind Energy Association (BGWEA) warns of an imbalance in the ten-year network development plan (2022–2031). The document highlights a disproportionate favouring of solar, with projections of 4.4 GW compared to just 0.34 GW for wind, despite over 4 GW of wind projects currently under development. The concern is that overconcentration in a single renewable source could undermine system efficiency and stability, especially during periods of high weather variability.

BGWEA argues that Bulgaria’s wind resource remains underexploited and that a more balanced approach would allow for the integration of greater volumes of clean, low-cost energy. Strengthening the role of wind in network planning would also enable a more geographically distributed generation landscape, easing network congestion and reducing costs associated with curtailment or balancing deviations.

The potential impact of the interconnection plan extends well beyond Bulgaria’s borders. The expansion to 10 GW will significantly increase the capacity for cross-border electricity trade, not only facilitating the export of renewable surpluses but also bolstering regional energy security. In a context of rising flexibility needs, the expansion will allow Bulgaria to access markets for reserve and backup services, enhancing the competitiveness of its renewable output both domestically and internationally.

The plan is complemented by several key initiatives. These include a programme supported by the EU recovery plan to roll out 82 energy storage projects totalling nearly 10 GWh, and the feasibility study for the East-West Energy Corridor, aimed at reinforcing interconnections with Greece, Turkey, Romania, and North Macedonia, potentially adding up to 2 GW per border.

Together, these actions outline a comprehensive vision for Bulgaria’s energy transition, combining infrastructure investment, regional integration, digitalisation, and storage. While the solar-wind imbalance remains a concern, the country appears to be on a path towards a more flexible, resilient, and EU-aligned electricity system.