Can South-East Europe sidestep Western Europe’s renewable oversupply problem?

South-East Europe is moving toward a decisive point in its renewable buildout, and the investment lesson from Western Europe is becoming harder to ignore. For years, the region’s combination of strong solar resources, limited wind corridors, low land costs, rising power prices and post-2022 energy security momentum created an attractive window for developers across Serbia, Romania, Greece, Bulgaria, Montenegro, Albania and Bosnia and Herzegovina.

That underlying need for additional generation still holds. But the economics are changing as more renewables arrive in concentrated bursts—often at the same time—into grids that were not built for high levels of intermittent output. By 2026, more advanced SEE markets are beginning to show early symptoms of what has already reshaped parts of Western Europe: renewable oversupply during specific hours, falling capture prices, grid congestion, balancing stress and a growing risk of curtailment.

From scarcity to congestion: the Western Europe template

Western Europe entered this phase first. Germany, Spain, the Netherlands and parts of the Nordic region have all experienced periods when strong wind or solar output pushed wholesale prices sharply downward or into negative territory. These episodes are no longer treated as rare anomalies; they are increasingly viewed as structural signals that power systems require more flexibility, including storage, stronger interconnections and demand-side responsiveness.

South-East Europe is not yet at the same level of saturation. Still, it is moving along a similar curve—where renewable abundance can become difficult to monetize if system integration lags.

Greece as the clearest warning signal

Greece illustrates how quickly a market can shift from renewable scarcity to renewable congestion. Rapid solar deployment has already produced visible midday price compression during periods of high irradiation and moderate demand. Solar generation peaks when the market is already oversupplied, which reduces realized capture prices while increasing reliance on batteries, interconnections and flexible balancing resources such as gas or hydro.

Bulgaria and Romania face rising flexibility pressure

Bulgaria is encountering similar pressures as solar additions expand rapidly while the legacy system remains shaped by coal and nuclear generation. During high-output periods, midday prices increasingly weaken; in turn, the value of flexible assets rises.

Romania’s system is described as more diversified due to nuclear and hydro capacity. However, strong wind generation in Dobrogea alongside expanding solar—and future Black Sea offshore wind ambitions—means Romania could also face oversupply periods if grid reinforcement and storage investment do not keep pace.

Serbia’s transition is beginning with different fundamentals

Serbia’s move toward oversupply dynamics comes from a different starting point. The country still relies heavily on lignite generation and has not yet reached the renewable saturation levels visible in Greece. Even so, wind development in Vojvodina and solar pipelines across eastern and southern Serbia indicate a clear direction.

The article points to early preparation for volatility through planned battery storage linked to EMS connection agreements—around 4.54 GWh—signaling that Serbia may be approaching a more flexible operating model even before full saturation arrives.

The core issue: timing plus weak shaping capacity

The central question for SEE markets is whether they can avoid repeating Western Europe’s mistakes. The region retains several advantages: renewable penetration remains lower in many countries than in earlier-saturated Western systems, giving governments and transmission system operators time to plan integration more deliberately. Hydropower flexibility across Albania, Montenegro, Bosnia and Herzegovina and Romania also provides a balancing resource at scale that many Western European systems lack.

Interconnections are improving too. Projects such as the Trans-Balkan Corridor are cited as potential ways to strengthen cross-border flexibility between Serbia, Montenegro and Bosnia and Herzegovina.

Why EU-Western Balkan trading signals matter

The Energy Community’s latest market observations underline why integration capacity cannot be treated as an afterthought. Q1 2026 brought a major shift in electricity flows between the EU and the Western Balkans: commercial exchanges fell by roughly 25%, while EU-to-WB6 flows dropped even more sharply. Price spreads alone were not sufficient to guarantee efficient arbitrage because carbon-related factors and structural constraints limited trading flows.

This reinforces a key takeaway for SEE markets: interconnection capacity, carbon structure and system flexibility determine whether renewable surplus becomes export value—or stranded energy that becomes increasingly costly to manage.

What happens if flexibility doesn’t scale

If SEE countries fail to coordinate grid expansion with storage deployment and market integration rules, renewable oversupply will become increasingly expensive rather than simply abundant. The article outlines likely consequences across the value chain: deteriorating capture prices for solar developers; congestion-related risks and balancing penalties for wind projects; increased curtailment imposed by TSOs; higher risk premiums demanded by lenders; and investor shifts away from standalone generation toward hybrid platforms or toward exposure in more mature markets.

The problem is framed not as “too much” renewables in absolute terms but as unshaped renewable electricity entering weak systems at the wrong time—when output clusters coincide with limited ability to absorb it.

Four defenses—and financing that must follow

The article argues that battery storage should be treated as a first line of defense. BESS can absorb midday solar output to reduce negative-price exposure and then discharge during evening peaks. It also supports balancing markets by reducing renewable imbalance costs. Greece, Serbia and Romania are already moving toward this direction—but the scale required by the early 2030s may be far larger than current pipelines suggest.

Hydropower is presented as a second defense: Albania and Montenegro could become premium balancing markets if reservoir dispatch is optimized around regional renewable volatility rather than domestic generation alone. Romania’s hydro fleet adds another layer of longer-duration flexibility that batteries may not cover economically once offshore wind and solar expand further.

Transmission forms a third defense by enabling surplus electricity to move toward demand centers or balancing resources across borders. The Montenegro–Italy cable, Serbia’s interconnections, Romania–Hungary links, Greece–Bulgaria connections—and again the Trans-Balkan Corridor—are described less as standalone infrastructure projects than as “renewable-value preservation” tools.

A fourth defense comes from demand-side flexibility. Industrial consumers such as data centers or electrolyzers—and other flexible loads like district cooling systems or tourism infrastructure—can absorb electricity during low-price periods if market design encourages flexible consumption. This matters for multiple national contexts cited in the article: Serbia’s industrial base; Greece’s tourism logistics systems; Romania’s manufacturing sector; and Montenegro’s coastal electricity demand.

Finally, financing must change with priorities shifting from funding megawatts alone toward funding flexibility alongside generation assets. Standalone solar and wind remain important—but investors may increasingly reward portfolios combining generation with storage capabilities, better grid positioning, industrial off-take arrangements and active trading capacity. Infrastructure funds are expected to favor projects designed to manage volatility rather than simply produce electricity.

A narrowing window before oversupply becomes defining risk

South-East Europe still has time to avoid the worst version of Western Europe’s renewable oversupply trap. But the window is narrowing because deployment appears to be accelerating faster than market architecture can adapt through auctions design details, grid queues management practices or project pipelines aligned with storage needs. If those elements expand without parallel investment in storage capacity, interconnections and balancing rules, oversupply could become a defining risk for late-2020s SEE electricity markets.

The countries that manage this transition well will not necessarily slow renewables—they will instead make renewable power more tradable, flexible and bankable so its value survives even when everyone else produces at similar times.