Battery deployment across Southeast Europe is expected to narrow the evening price premium that has created a commercial opportunity for storage. Bulgaria’s fleet is estimated at more than 19 GWh, making its potential effect on prices a regional issue. A more stable price profile is expected, alongside occasional extreme events.
Solar generation pushes prices down around midday, then prices rise as solar output declines, demand stays high and flexible generation becomes scarce. In Serbia in August, midday prices were around EUR 66/MWh, while prices averaged roughly EUR 244/MWh around hour 20. Charging batteries before the evening price ramp and discharging during it could raise the low-price trough and reduce the evening peak.
Storage is not expected to eliminate the premium. Weather, hydro conditions, thermal outages, interconnector congestion and demand can still cause scarcity events that batteries cannot address. Longer-duration storage may also maintain an evening premium later into the night, after two-hour systems have emptied.
The expected narrowing of the average evening premium could alter project returns for investors. A project commissioned in 2028 should not be valued using the 2026 evening price curve, and developers are advised to model storage additions in every major neighbouring market before a project reaches mid-life.
The investment case is expected to shift, not disappear: the premium remains investable but should be treated as a declining resource. Batteries may earn less from routine daily cycling and more by selecting the most valuable days, providing balancing services and optimising portfolios.