South East Europe’s power system is seeing a shift in how electricity can be traded as battery storage expands. The region combines rapid solar deployment, evening scarcity risk, hydro output variability, grid congestion, and market integration that is still developing. Against that backdrop, storage is increasingly positioned as a flexible resource for multiple market needs.
A battery functions as more than generation-linked infrastructure. Commercially, it operates as a flexible trading asset that can capture value across different market segments. It absorbs electricity when the system is long and releases it when the system is short, aligning dispatch with changing price conditions.
That time-shifting capability can also affect exposure to imbalances and help support contracts and grid operations. Storage can reduce imbalance risk, support PPAs, provide balancing services, and manage congestion. As European markets move toward 15-minute pricing and finer granularity, the potential value of flexibility increases.
European outlook on storage and flexibility
ENTSO-E’s 2026 Summer Outlook described the scale of the change underway across Europe. It reported that battery storage capacity doubled to 29 GW compared with the previous summer. The outlook also highlighted flexibility solutions beyond storage, including interconnection, demand-side response, and operational coordination.
ACER’s monitoring of European electricity and gas markets has repeatedly pointed to the need for flexibility resources as renewable generation grows. It also links the requirement to rising daily price volatility across the continent. These developments provide context for how storage may be used in markets with frequent swings in supply and demand.
Price patterns linked to solar growth
The European trend is relevant to South East Europe because solar output patterns can drive sharp intraday price movements. Strong solar growth can lead to low or even negative prices during sunny midday hours. As solar production falls in the evening while demand remains elevated, prices often rise sharply.
This daily spread creates commercial opportunities for battery operators based on shifting energy across time. In practice, the value of storage is not limited to energy arbitrage alone. Multiple revenue streams can be tied to market participation across day-ahead, intraday, balancing, contracting arrangements, and congestion-related needs where rules allow.
Revenue streams from day-ahead to congestion management
One stream comes from day-ahead arbitrage, with batteries charging during low-price periods and discharging when prices are higher. A second stream involves intraday optimization as forecasts and market conditions change closer to delivery. A third stream comes from balancing participation through flexibility services or through reducing imbalance costs.
Storage can also support PPA firming by converting variable renewable output into a more predictable supply profile. A further use case is congestion management, which can reduce curtailment and support local grid constraints where regulations permit. The different roles depend on how market rules enable participation across segments.
Where storage value may be concentrated in Southeast Europe
In South East Europe, storage value is expected to be greatest when several conditions overlap. These include high solar penetration, weak midday prices, strong evening demand, constrained interconnectors, active intraday markets, and accessible balancing mechanisms. Greece, Bulgaria, Romania, Hungary, and Serbia each show elements of this combination.
The trading economics are also shaped by project-specific parameters and operational constraints. Profitability depends on degradation rates, cycling strategies, warranty conditions, augmentation costs, grid fees, market access arrangements, tax treatment, collateral requirements, software optimization capabilities, and regulatory frameworks. Operational design choices can materially affect outcomes even when projects appear profitable in initial assessments.
Operational skills and contracting changes
The complexity of storage trading changes the skill set required by asset owners. A solar plant can largely operate as a production asset, while a battery must be actively optimized. Owners typically need forecasting capabilities, market access pathways, trading systems, and compliance processes to participate effectively.
Batteries are also influencing PPA structures for corporate buyers seeking products aligned with their consumption profiles. Some buyers are less interested in raw solar generation that exposes them to evening market prices. Storage enables shaped renewable products by supporting more predictable delivery profiles relative to variable generation.
Market design considerations for regulators
For traders, storage adds optionality and risk-management flexibility across multiple market stages. Batteries can reduce short exposure during scarcity periods and absorb negative-price risk during low-price hours. They can also provide intraday flexibility and help manage renewable forecast errors.
Regulators play a role through market design that determines how storage participates across segments without being disadvantaged. The source highlights concerns such as double charging risks, restrictive licensing requirements, or unclear regulatory treatment for storage assets. Excessively rigid rules could limit the flexibility batteries provide to the system.
Implications for 2026–2028 power price formation
Looking ahead to 2026–2028, batteries are expected to play an increasingly important role in shaping electricity prices across South East Europe. The source does not indicate that volatility will disappear; instead it points to changes in how value from volatility may be captured by different participants. Midday negative-price periods may become charging opportunities as batteries respond to those conditions.
Evening scarcity is expected to translate into discharge value for storage operators under these dynamics. Intraday forecast deviations are also described as a basis for optimization revenue where markets allow participation close to delivery. In the older SEE power market model described in the source, traders generated value primarily by moving electricity across borders.
In the emerging market environment referenced there, traders are expected to increasingly create value by moving electricity across time rather than focusing mainly on cross-border flows.