Solar-driven volatility widens intraday spreads across South-East Europe, reshaping trading and asset economics

South-East Europe’s intraday power markets are moving into a more volatile phase as solar generation expands and begins to reshape how prices form hour by hour. In calendar week 13, intraday spreads widened across multiple markets, highlighting how quickly forecasted supply can diverge from real-time conditions—and why that divergence is increasingly central to trading strategy.

Spreads widen as forecasted and actual solar output diverge

Across the region, typical intraday spread ranges moved to about €20–40/MWh, while spikes reached €50–90/MWh during periods of system imbalance. The underlying driver is the gap between day-ahead forecasts and actual generation: solar output may be predictable over a seasonal horizon, but it remains sensitive to short-term weather factors such as cloud cover and atmospheric variability.

That sensitivity means day-ahead expectations often fail to match real-time production. When the mismatch grows, imbalances must be corrected through intraday trading rather than being fully absorbed elsewhere in the system.

Midday pressure and evening peaks become more pronounced

The price profile associated with higher solar penetration has become increasingly visible in SEE markets. During midday hours—when solar output is strong—prices can fall well below day-ahead levels. As generation declines later in the afternoon and into the evening, prices tend to rise sharply, reflecting the need to dispatch higher-cost units that are often gas-fired.

This low-midday/high-evening pattern has been familiar in Western Europe, including Germany and Spain. Its emergence in South-East Europe signals that the region’s energy transition is accelerating enough for operational realities of renewables variability to show up directly in market outcomes.

Less flexibility means volatility hits prices rather than being absorbed

A key difference versus Western Europe is system flexibility. SEE markets have limited battery storage capacity, constrained interconnections, and continued reliance on thermal generation. With fewer balancing tools available at scale, imbalances are more likely to translate into price volatility instead of being absorbed smoothly by the grid.

Intraday becomes the main arena for value creation

For traders, this environment can be attractive because it shifts attention toward short-term positioning. Intraday markets are increasingly described as the primary venue for value creation—less about longer-term directional bets and more about forecasting renewable output accurately enough to anticipate system imbalances.

Flexible assets gain revenue potential—but liquidity remains uneven

The widening spreads also carry implications for asset valuation. Flexible resources such as battery storage, fast-ramping gas plants, and demand response systems are better positioned to capture intraday spread opportunities, improving their potential revenue outlook.

At the same time, greater reliance on intraday trading raises the stakes for liquidity and market design. While exchanges across SEE have made progress developing intraday platforms, liquidity remains uneven across countries; larger markets such as Hungary and Romania are leading the way.

What comes next

The trend toward wider intraday spreads is expected to continue as solar capacity grows further and wind generation remains variable. As forecast errors between expected and actual supply become harder to eliminate under changing weather conditions, intraday trading—and the ability to manage imbalance risk—will likely remain central for both market participants and flexible asset owners.