Battery storage is expanding rapidly across Southeast Europe, with Hungary’s observable capacity expected to exceed 1 GW later in 2026. As more batteries trade, price differences can narrow, reducing the volatility-driven opportunity that attracted investors. Long-term forecasts therefore need to account for changing market conditions.
Bulgaria’s latest estimate put storage at more than 6.2 GW of power and 19 GWh of energy. In Romania’s installed storage capacity, power rose from 494 MW at the start of 2026 to 1,162 MW by October, an increase of about 668 MW. Hungary’s observable capacity grew from 197 MW in January to 778 MW by July 2026, then continued rising above 1 GW later in the year.
Storage growth alters battery revenue assumptions
Early investors can capture scarcity rents that later projects may find difficult to reproduce. Applying early returns across the full operating life of every new battery risks assuming that competitors will not respond. A 15-year valuation using today’s highest spreads makes that assumption even as new capacity changes market conditions.
A stronger valuation model treats storage penetration as an endogenous variable, with expected market entry influencing projected returns. As capacity grows, ordinary arbitrage margins compress and competition in balancing markets increases. Current spreads should therefore not automatically be assumed to persist throughout a battery’s life.
As storage markets mature, value shifts towards location, duration, contract structure and portfolio integration. Batteries behind network constraints, or those with access to higher-value services, can still outperform. The investment case increasingly depends on an asset’s position and revenue options, rather than volatility alone.
The storage thesis remains intact, but the sector is expected to develop from a simple volatility trade into an infrastructure-and-optimisation business. The most successful batteries will remain useful even after their deployment helps reduce the price volatility that initially attracted investment.