In Bulgaria, battery storage is adding a timing dimension to Southeast European power trading, as traders weigh when and where to sell electricity and consider batteries’ state of charge. The country’s battery fleet exceeds 6.2 GW of storage power. Romania had 1.162 GW of storage on 1 October, while two battery projects were commissioned in Greece in October.
Storage adds a timing dimension to power trading
Power trading has traditionally centred on generation, consumption and cross-border transmission. Storage adds time as a fourth dimension, allowing electricity to be sold at a different time from when it was generated or imported. This gives traders an additional option in their portfolios.
Battery fleets can absorb and release energy in volumes comparable to major interconnector flows. Traders are increasingly weighing whether to transmit electricity immediately or store it for a later sale, alongside decisions about where power is cheapest. Storage can preserve energy through congestion, reduce imbalance or allow a portfolio to wait for a better intraday price.
This flexibility can make storage economically equivalent to temporal transmission capacity. Its effects are expected to be strongest in markets with high solar penetration and limited evening electricity supply, where batteries can retain some low-value midday solar power and export it later. In Greece, a 330 MW / 790 MWh battery in Thessaly and a separate 100 MW / 200 MWh HELLENiQ battery project were commissioned in October.
Shifting exports from midday to later in the day can change the price signal seen by neighbouring countries and reduce the value of some traditional cross-border strategies. Southeast Europe’s leading trading platforms will need to optimise location, timing and state of charge simultaneously.