The Greek energy regulator, the Regulatory Authority for Waste, Energy and Water (RAAEY), has approved a sweeping revision of the country’s Balancing Market rules, a move that formally integrates electricity storage into the core of Greece’s power system operations. The reform reflects a strategic shift by the regulator, which now explicitly recognises energy storage as a cornerstone of grid stability and security at a time when renewable energy sources are gaining an ever-larger share of electricity generation.
One of the most consequential changes concerns the size threshold that separates large from small storage facilities. This limit has been cut sharply from 40 MW to 10 MW. Storage units above this level will be required to participate in electricity markets as independent market players and will no longer be allowed to operate as part of aggregated portfolios. According to RAAEY, the rationale behind this decision is the need for closer operational oversight and more effective management of local grid constraints, while keeping open the possibility that the threshold could be revised again in the future as the market matures.
The new framework also tightens operational discipline for storage operators. Market participants representing dispatchable storage units will now be obliged to submit detailed schedules for both energy injection into the grid and energy absorption within strict deadlines following the results of the day-ahead and integrated scheduling process. Although parts of the market had raised objections, the regulator argues that this requirement is essential to give the system operator a clear and timely picture of charging and discharging strategies, reducing the risk of unexpected deviations that could threaten overall system stability.Additional weight is given to rules governing how storage facilities restore their state of charge. The revised code explicitly bans the shifting of imbalances through the intraday market and imposes time limits on transactions ahead of the start of balancing periods. These provisions are designed to curb practices that could distort competition or undermine the integrity and smooth functioning of the balancing market.
The regulatory overhaul creates clear winners and losers. Companies investing in, or already operating, large-scale battery projects of 10 MW and above are among the main beneficiaries. For the first time, they gain transparent and predictable access to the Balancing Market and can be fully compensated for services such as rapid response to supply-demand mismatches. Renewable energy producers, particularly wind and solar operators, also stand to gain. The growing role of storage reduces energy curtailments during periods of oversupply and helps the system cope with sudden weather-driven fluctuations, leading to more stable output and revenues.
On the other side of the ledger, conventional power producers are expected to come under pressure. Until now, balancing services in Greece have been dominated largely by natural gas-fired plants. The entry of large-scale storage erodes this position, as batteries can often provide balancing services more quickly and at lower cost, reducing revenues for thermal generators. The new rules also disadvantage market players who had relied on exploiting flexibility in the intraday market to correct positions at the last minute or transfer imbalances, practices that are now explicitly restricted. Finally, smaller or less technologically advanced storage operators may struggle with the higher compliance requirements, facing increased costs and, in some cases, temporary exclusion from effective market participation.
