The acceleration of renewable energy across Southeast Europe is exposing a structural reality that had long been underestimated: the region is not constrained by a lack of generation ambition, but by the ability of its grids to absorb, transport and monetise that generation.
From Serbia and Bosnia and Herzegovina to North Macedonia, Montenegro and Albania, project pipelines for solar and wind have expanded rapidly over the past three years. National targets are converging toward 40–50% renewable electricity shares by 2030, supported by auctions, bilateral agreements and increasing private-sector investment. Serbia alone is targeting 45.2% renewable electricity, while Albania already operates a predominantly hydro-based system and is now adding solar capacity at scale.
On paper, the region appears well positioned for a rapid energy transition.
In practice, the constraint is shifting from megawatts to megavolt-amperes—from generation capacity to grid capability.
Adequacy is not the constraint—integration is
System adequacy across Southeast Europe remains broadly intact. Seasonal outlooks indicate that countries such as Serbia and Montenegro are not expected to face structural supply shortages under normal operating conditions. In aggregate terms, the region can generate enough electricity to meet demand.
The emerging issue is more granular and more operational.
Renewable energy—particularly solar—is arriving in concentrated volumes, both geographically and temporally. Large clusters of projects are being developed in northern Serbia, eastern Bosnia and parts of Romania and Bulgaria. At the same time, generation peaks are increasingly synchronised, with solar output concentrated in midday hours.
This creates localized congestion and temporal imbalance.
Electricity is available when it is least needed and constrained when it is most valuable. The grid, originally designed for dispatchable thermal and hydro generation, struggles to accommodate these new patterns.
Transmission operators are beginning to respond. In Serbia, connection procedures for variable renewable energy are now explicitly linked to system capability, with provisions allowing delayed connection based on network conditions. This is a clear signal that connection demand is beginning to exceed what the system can immediately accommodate.
The same pattern is visible across the region.
The rise of congestion as a structural feature
Congestion is no longer an occasional operational issue. It is becoming a structural feature of Southeast European electricity markets.
In solar-heavy zones, midday generation increasingly exceeds local demand and export capacity. Without sufficient transmission or storage, this leads to:
• Price compression or near-zero pricing during peak solar hours
• Curtailment of renewable output
• Reduced capture prices for generators
At the same time, evening demand peaks require dispatchable or imported power, often at significantly higher prices. Intraday price spreads of €30–70/MWh are becoming common, with extreme cases exceeding €100/MWh.
This volatility is not simply a market phenomenon. It is a direct reflection of insufficient flexibility and transmission capacity.
Cross-border infrastructure becomes critical
Southeast Europe’s geography makes cross-border transmission a key component of system stability.
The region sits at the intersection of EU and non-EU electricity markets, with significant interconnections linking Serbia, Bosnia, Montenegro and North Macedonia to Hungary, Romania, Bulgaria, Croatia and Greece.
However, much of this infrastructure was designed for different flow patterns.
Historically, electricity moved from large thermal plants to domestic load centres, with limited cross-border optimisation. Today, flows are increasingly driven by:
• Renewable generation patterns
• Price differentials between markets
• Carbon-adjusted economics
This requires a different type of network—one capable of handling high-volume, bidirectional flows.
The current project pipeline reflects this need. Planned investments include:
• The Gacko–Brezna 400 kV corridor linking Bosnia and Montenegro
• The Trans-Balkan 400 kV upgrades connecting Serbia, Bosnia and Montenegro
• Reinforcements along the Trebinje–Podgorica axis
• The East–West corridor between North Macedonia and neighbouring systems
These projects are not incremental upgrades. They are foundational investments required to unlock renewable capacity and enable regional market integration.
Without them, renewable generation remains stranded or underutilised.
Flexibility deficit emerges as core constraint
Beyond transmission, the second major bottleneck is flexibility.
Southeast Europe’s power systems were built around coal and hydro, with limited need for rapid-response balancing. As renewable penetration increases, this model becomes less effective.
The system now requires:
• Fast-ramping capacity
• Short-term balancing resources
• Intraday optimisation capability
Battery storage is emerging as a key solution. Across the region, project pipelines for BESS are expanding, with costs currently in the range of €350–500/kWh.
However, deployment remains limited relative to need.
Large-scale storage projects, such as Albania’s planned Moglice pumped-storage extension (~1.6 GW, ~30 GWh), illustrate the scale required to stabilise renewable-heavy systems. These assets provide not only energy shifting but also system-wide balancing support.
Without such investments, the region risks increasing reliance on curtailment as a balancing tool—a solution that undermines both project economics and decarbonisation objectives.
Distribution networks: The hidden bottleneck
While transmission receives most attention, distribution networks are emerging as a parallel constraint.
A significant portion of new solar capacity—particularly commercial and industrial installations—is connected at lower voltage levels. These networks were not designed for two-way power flows or high levels of distributed generation.
As a result:
• Localised congestion occurs even when transmission capacity is available
• Connection queues grow at the distribution level
• Flexibility options such as demand response remain underutilised
The lack of coordination between transmission and distribution operators exacerbates the problem. Data exchange, forecasting and dispatch coordination are still developing, limiting the system’s ability to respond dynamically.
Market design lags physical reality
Infrastructure constraints are compounded by market design.
Electricity markets in Southeast Europe are evolving, but not yet fully aligned with the needs of a renewable-dominated system. Key gaps include:
• Limited ancillary service markets
• Weak price signals for flexibility
• Incomplete integration of storage and aggregators
• Regulatory barriers to cross-border optimisation
Flat or regulated tariffs further reduce incentives for consumers to adjust demand in response to price signals.
The result is a system where physical constraints are not fully reflected in market behaviour, leading to inefficiencies and missed opportunities for optimisation.
Economic implications for renewable projects
For renewable developers, these constraints translate into tangible financial risks.
Projects that secure grid connection may still face:
• Curtailment during high-generation periods
• Lower-than-expected capture prices
• Increased volatility in revenue streams
In practical terms, not all megawatts are equal.
Projects located in well-connected nodes with access to transmission and flexibility resources will outperform those in constrained areas. This creates a two-tier market, where location and integration capability become as important as resource quality.
For lenders and investors, this changes the assessment of bankability.
Grid risk—once considered secondary—is becoming a primary factor in project evaluation. Financing structures increasingly account for curtailment scenarios, connection delays and price volatility.
Industrial demand adds new pressure
The rise of CBAM and carbon-linked trade adds another dimension.
Energy-intensive industries across Southeast Europe are seeking low-carbon electricity to maintain competitiveness in EU markets. This creates additional demand for renewable generation, but also for reliable and flexible supply.
Industrial consumers cannot rely on intermittent generation alone. They require electricity that matches production schedules, which in turn requires storage, flexible generation or grid support.
This reinforces the need for integrated solutions combining generation, storage and transmission.
The path forward: Integrated system development
The solution is not singular. It requires coordinated investment across multiple layers of the system.
Transmission expansion must accelerate, particularly cross-border projects that enable regional optimisation. At the same time, storage deployment must scale, providing the flexibility needed to manage variability.
Market design must evolve to support these changes, introducing stronger price signals and enabling new participants such as aggregators and storage operators.
Distribution networks must be upgraded to handle decentralised generation and two-way flows.
Most importantly, these elements must be developed together.
Isolated investment—whether in generation, transmission or storage—will not be sufficient. The system must be treated as an integrated whole, with each component supporting the others.
A defining decade for Southeast Europe
Southeast Europe is entering a defining phase in its energy transition.
The region has the resources, the policy direction and the investment interest to expand renewable energy at scale. What it now requires is the infrastructure and system design to support that expansion.
The question is not whether the grid can withstand more renewables in a technical sense.
It is whether it can do so efficiently, profitably and sustainably.
On the current architecture, the answer is increasingly no.
With targeted investment, coordinated planning and market reform, the answer can become yes.
The outcome will determine not only the success of the region’s energy transition, but also its broader economic positioning within a carbon-constrained European market.
