Serbia’s day-ahead market showed an almost EUR 179/MWh gap between its daily low and hour-20 high on 15 October, illustrating the potential value of battery flexibility. The spread alone is not a bankable revenue measure: earnings depend on the prices and operating conditions an asset can actually capture. For investors and lenders, that distinction affects whether a visible market opportunity can support a reliable revenue model.
The price was near EUR 189.9/MWh at the daily low and reached EUR 368.6/MWh at hour 20. With an illustrative round-trip efficiency of 90%, a battery buying 1 MWh at the low and returning 0.9 MWh after efficiency losses would produce about EUR 332 in sales against roughly EUR 190 in charging costs. That leaves around EUR 142/MWh in gross capture, before degradation, fees, imbalance costs, the optimiser’s share and financing costs.
This calculation assumes the battery can charge at the low price and discharge into 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. A daily maximum and minimum do not show whether the asset can make those trades under its actual operating constraints.
The shape of prices within the day also matters. Several low-price hours followed by several expensive hours can create different revenue profiles for a two-hour battery and a four-hour battery, even if both face the same maximum and minimum prices. A battery that begins the day partially discharged may miss the best charging window. An asset reserved for balancing services may also intentionally keep capacity unavailable for pure arbitrage.
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 Southeast European markets was EUR 60.30/MWh, while the listed Serbia and Greece averages differ by EUR 61.32/MWh.
Those regional comparisons do not represent revenue a battery can automatically earn. It cannot directly monetise a geographic price spread without transmission capacity and trading positions; instead, it captures differences over time at its own node or bidding zone.
A bankable model should simulate the asset 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, rather than the difference between the single cheapest and most expensive hour.