Serbia’s day-ahead market recorded a nearly EUR 179/MWh gap between the daily low and the hour-20 peak on 15 October, highlighting the potential value of battery flexibility. But the spread is not a bankable revenue measure. Actual earnings depend on the hourly prices and operating constraints an asset can capture.
The day-ahead price was near EUR 189.9/MWh at its daily low and climbed to EUR 368.6/MWh at hour 20. With an illustrative round-trip efficiency of 90%, a battery buying 1 MWh at the low and selling 0.9 MWh after efficiency losses would make about EUR 332 in sales against roughly EUR 190 in charging costs. That would leave around EUR 142/MWh in gross capture.
The illustrative figure excludes degradation, fees, imbalance costs, the optimiser’s share and financing costs. It also assumes the battery can charge at the low and discharge during the high-price hour. The sequence of hourly prices, battery duration, round-trip efficiency, state of charge, market access and degradation all affect the result.
Price patterns matter alongside the daily extremes. Several low-price hours followed by several expensive hours can yield different revenue profiles for a two-hour battery and a four-hour battery, even if both encounter the same maximum and minimum. A battery that begins the day partly discharged may miss the best charging window, while one reserved for balancing services may intentionally keep capacity unavailable for arbitrage.
Regional baseload prices are not 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 difference between the highest- and lowest-priced Southeast European markets was EUR 60.30/MWh. However, the listed averages for Serbia and Greece differ by EUR 61.32/MWh.
A battery cannot directly monetise a price difference between locations without transmission capacity and trading positions. Storage instead captures price differences over time at its own node or bidding zone. Regional baseload comparisons therefore differ 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.