Serbia’s day-ahead market recorded an almost EUR 179/MWh gap between the daily low and the peak at hour 20 on 15 October, highlighting the potential value of battery flexibility. But the spread is not a bankable measure of revenue, which depends on the hourly prices and operating constraints an asset can actually capture. The market’s daily low was about EUR 189.9/MWh, while the hour-20 price reached EUR 368.6/MWh.
Using an illustrative round-trip efficiency of 90%, a battery buying 1 MWh at the low and selling 0.9 MWh after efficiency losses would earn about EUR 332 in sales against roughly EUR 190 in charging costs. That would leave around EUR 142/MWh in gross capture. The calculation excludes degradation, fees, imbalance costs, the optimiser’s share and financing costs, and assumes the battery can buy at the low and discharge during the high-price hour.
The sequence of hourly prices and the battery’s duration, round-trip efficiency, state of charge, market access and degradation all affect the outcome. Several low-price hours followed by several expensive hours can produce different revenue profiles for a two-hour battery and a four-hour battery, even when they face the same maximum and minimum prices. A battery that begins the day partially discharged may miss the best charging window, while one reserved for balancing services may deliberately leave capacity unavailable for arbitrage.
Regional baseload prices differ from storage revenue
In Week 42, average baseload prices were EUR 247.89/MWh in Serbia, EUR 246.87/MWh in Hungary, EUR 240.51/MWh in Romania, EUR 235.89/MWh in Bulgaria, EUR 230.49/MWh in Croatia and EUR 186.57/MWh in Greece. The reported gap between the highest- and lowest-priced Southeast European markets was EUR 60.30/MWh, although the listed Serbian and Greek averages differ by EUR 61.32/MWh.
A battery cannot directly monetise a geographic price difference without transmission capacity and trading positions. Instead, storage captures price differences over time at its own node or bidding zone, so regional baseload comparisons are distinct from the revenue an asset can achieve.
A bankable model should simulate the battery hour by hour across many price paths, enforce charging and discharge constraints, include auxiliary load and degradation, and calculate debt-service metrics. Multiplying a fixed number of cycles by an average spread is too crude because storage itself changes the hourly price curve. Lenders should value dispatchable hourly capture, not the difference between the single cheapest and most expensive hour.