South-East Europe is accelerating into a renewable future, but the systems meant to stabilise, balance and move that electricity across borders are not keeping pace. The result is a region that risks turning opportunity into instability, unless balancing capacity strengthens and cross-border congestion finally yields to openness and trust.
South-East Europe’s electricity story is increasingly defined not just by legacy structures and institutional inertia, but by the accelerating collision between renewable expansion, balancing capability and hard physical cross-border constraints. The region is moving into a power future where wind, solar and hydropower will inevitably dominate, yet the systems that must absorb, stabilise and exchange that power remain only partially prepared. The earlier narratives about price volatility, the seventy-percent rule, CBAM pressures and the Trans-Balkan Corridor can only be fully understood when these three dimensions—renewables, balancing and congestion—are placed at the centre of the analysis.
Renewables are no longer an aspiration in SEE; they are materialising at scale. Greece is already living inside a renewable-heavy profile. Romania is rapidly accelerating new projects. Bulgaria and Serbia are waking up to large-scale developments after years of hesitation. Montenegro and Bosnia retain hydropower dominance, while even Hungary, structurally constrained, is trying to build more capacity simply to offset import vulnerability. But renewables do not simply add capacity. They change the entire physics of the system. They generate intermittently. They require rapid response capability. They create periods of oversupply and scarcity that traditional coal-based logic cannot manage. Instead of being an add-on, renewables force a structural redesign of how SEE electricity behaves.
That is where balancing becomes decisive. A renewable system is only as strong as its balancing ecosystem. Western Europe entered high-renewable phases with strong interconnections, robust ancillary services, developed balancing markets, storage investment and flexible hydro and gas capacity to stabilise fluctuations. South-East Europe is entering the same era with weaker liquidity, fewer mature balancing tools, limited storage and regulatory cultures still oriented around hourly stability rather than dynamic, sub-hourly precision. Hydropower remains the region’s most precious balancing resource, yet it is heavily vulnerable to climate variability. Serbia, Montenegro and Bosnia depend on water cycles that cannot be guaranteed. Even when hydrology is strong, it cannot endlessly absorb volatility created by expanding renewables. When hydrology weakens, much of the balancing safety net disappears.
This fragility becomes more dangerous because cross-border capacity, which should act as the ultimate stabiliser, still behaves like a constricted pipe. Congestion in SEE is not theoretical; it is the lived daily geography of regional power. Interconnectors that should be moving Greek solar to Hungary, Romanian wind to the Western Balkans, or Balkan hydro to Central Europe are too often constrained, underutilised or administratively limited. Not because engineering capability is absent, but because institutional hesitation, conservative transmission practices, incomplete harmonisation and politically cautious operational cultures stop electricity from behaving like the regional commodity it is meant to be.
When borders do not open fully, renewable surpluses become domestic headaches rather than shared resources. Balancing burden remains national instead of regional. Price crises become local explosions instead of continental adjustments. Meanwhile, traders price structural uncertainty into markets, industries hedge defensively and households remain exposed to electricity as a recurring vulnerability rather than a predictable service.
Seen through this lens, the four major SEE electricity narratives align into one systemic picture. Persistent price instability is not merely the legacy of fossil systems or poor governance; it is the structural consequence of renewables expanding faster than balancing sophistication and faster than grid openness. The EU’s seventy-percent cross-zonal rule is therefore not abstract regulation but a functional stability instrument. Europe understands that without mandatory openness, a renewable continent fragments and destabilises. South-East Europe’s hesitation to fully embrace this obligation is, in truth, hesitation to embrace the only real safety mechanism renewables depend upon.
CBAM reinforces this reality by attaching economic consequences to energy choices. High-carbon systems cannot rely indefinitely on coal to provide stability, particularly when those systems face carbon penalties that erode competitiveness. At the same time, renewable systems without balancing and open networks risk financial unpredictability. CBAM therefore does not merely demand decarbonisation; it demands systems capable of living with decarbonisation.
And then comes the Trans-Balkan Electricity Corridor — not just a symbolic project, but the structural bridge between ambition and stability. If fully utilised and matched with regulatory courage, it has the power to reduce congestion, enable meaningful balancing cooperation and convert renewable surpluses into regional stabilisers rather than wasted or curtailed capacity. If it remains infrastructural ambition constrained by conservative behaviour, SEE will possess modern assets without modern outcomes.
The decisive question for the coming decade is therefore not whether South-East Europe can build renewable capacity. That race has already begun and will accelerate regardless of hesitation. The real test is whether the region can build the balancing strength, storage capability, flexible market design and cross-border openness required to ensure that renewables stabilise rather than destabilise the system. Success brings price reduction, improved competitiveness, reduced vulnerability, stronger investment confidence and deeper European integration. Failure brings the opposite: volatility disguised as progress, decarbonisation without stability, and a region permanently operating close to risk.
South-East Europe no longer has the luxury of debating whether it participates in Europe’s electricity evolution. It already has. Renewables are here. Infrastructure is rising. The policy frameworks exist. What remains uncertain is whether the region will construct the balancing and cross-border reality capable of sustaining this future, or whether it will enter a renewable era with systems not yet designed to endure it.
Renewables cannot succeed alone. They require trust, openness and system courage. Whether South-East Europe can deliver those qualities will decide not just its energy future, but its economic and political resilience in the decade ahead.