The planned increase in electricity transmission capacity between Türkiye and Bulgaria could become one of the most important trading developments in south-east Europe. The two countries are discussing projects that could raise interconnection capacity by 700–1,100 MW, creating a stronger bridge between the Turkish and Balkan power systems. For electricity traders, this is not an engineering footnote. It could change hourly spreads, congestion patterns and balancing dynamics across the region.
Türkiye is a large and growing electricity market with its own demand peaks, renewable expansion and gas-fired generation base. Bulgaria, meanwhile, is becoming a storage-heavy and increasingly flexible SEE market, with battery capacity expected to rise sharply by the end of 2026. Stronger interconnection between the two systems would create new opportunities to arbitrage price differences during solar oversupply, evening ramps, heatwaves and winter tightness.
The commercial value depends on directionality. During periods of high Turkish demand, Bulgaria and neighbouring markets may export power south-east if capacity is available. During periods of Bulgarian or Balkan scarcity, Türkiye could provide supply support, depending on its own system balance. The interconnector therefore becomes a volatility valve. It will not eliminate price spreads, but it can reshape them.
The development also matters for Greece, Romania and Serbia. Bulgarian prices sit between several regional market zones. A stronger Turkish link can affect flows into Greece, Romania and the wider Balkan system by changing Bulgaria’s import-export balance. Traders watching only national fundamentals will miss the wider interaction.
Storage makes the story more important. Bulgarian batteries may charge during low-price renewable hours and discharge when Turkish or regional demand lifts prices. That creates new strategies around interconnector capacity, intraday nominations and balancing services.
The risks are familiar: regulatory coordination, capacity allocation, market coupling limits and grid-security constraints. More capacity does not automatically mean frictionless trading. Yet the direction is clear. Türkiye is becoming a stronger price influence on Balkan electricity, and Bulgaria is becoming the gateway through which that influence enters SEE trading books.
