South East Europe’s power markets are increasingly influenced by a timing mismatch between solar output and electricity demand. Solar generation tends to push prices down during the day, particularly around midday. As solar output falls after sunset, evening demand rises, shifting price patterns. ACER linked the lack of flexible resources to replace solar generation after sunset with 2024 summer price spikes.
Batteries are positioned to respond to that pattern by shifting electricity across time. They can charge during low-price or negative-price hours and discharge during evening peaks. They can also provide balancing services, reduce curtailment, support grid stability and improve the shape of renewable PPAs. In markets with rising intraday volatility, that operational flexibility becomes a key attribute.
Bulgaria’s RESTORE-backed storage programme and approved projects
Bulgaria is cited as the most visible regional test case for large-scale storage deployment. The EU’s Recovery and Resilience-backed RESTORE investment supports the installation and commissioning of grid-scale electricity storage facilities. The programme targets 3,000 MWh of usable energy capacity, with a €603 million contribution, and is scheduled for completion by 30 June 2026.
Beyond the RESTORE support, Bulgaria has also approved additional storage capacity through standalone projects. Regional energy reporting states that Bulgaria approved support for 82 standalone battery energy storage projects. The projects total around 9.71 GWh of capacity and roughly €587 million in subsidies.
The scale of approvals is presented as broader than a single-country development. Storage value in South East Europe is associated with strong solar growth, grid constraints, evening price spikes, hydro variability and market integration gaps. Batteries are described as part of a shift in market architecture rather than an add-on to existing generation.
Battery revenue streams beyond energy arbitrage
The revenue model for batteries extends beyond simple energy arbitrage in markets where rules allow it. A battery can generate income by buying electricity at low prices and selling at higher prices, but that is only one component. Depending on market design, batteries may also earn from balancing services and other ancillary products. These can include frequency response, congestion management and reserve capacity.
Additional revenue opportunities referenced include PPA firming and imbalance-risk reduction. The range of services depends on how markets define participation and remuneration for storage assets. For renewable developers, pairing solar with storage can change the timing of output delivered to the system. It can shift generation from weaker midday periods into stronger evening hours while reducing exposure to negative prices.
The same configuration can also be used to offer corporate buyers a different product structure. Instead of supplying only green electricity, developers may supply shaped green electricity through the combined asset operation. For industrial consumers, behind-the-meter or contracted storage can reduce peak exposure and support hedging strategies. This use case is linked to widening hourly spreads in the market.
Operational roles for system operators and policy requirements
Batteries can also affect system operations by reducing stress during periods of high renewable output or tight balance conditions. They can respond faster than thermal plants and absorb surplus renewable generation without fuel costs. They provide flexibility that can be used to manage variability across operating horizons. However, the extent of this value depends on regulatory arrangements.
The source highlights that battery economics can be weakened if regulation creates barriers or misaligned charges for storage participation. Examples include grid fees, licensing rules, balancing-market access constraints or double-charging structures. Market rules are therefore described as central to enabling batteries to charge, discharge and provide services across multiple markets. The requirement is that storage participation should not be penalized through treatment as both a final consumer and a generator.
The next investment cycle in South East Europe is framed around flexibility rather than capacity additions alone. Batteries are described as one direct way to monetize that shift in value drivers created by solar growth and price volatility patterns. Bulgaria’s deployment direction is presented alongside the broader question of which regional markets will implement rules, grids and revenue structures quickly enough for bankable infrastructure development.
Elevated by virtu.energy
