Modo Energy's ME BESS PL benchmark is now live on the Terminal. An unconstrained four-hour battery in Poland could have earned 1.67 million PLN/MW-year in July 2026, down 9% from 1.84 million in June as the scarcity that had lifted aFRR capacity and day-ahead prices eased.

July sat almost a quarter above the 1.36 million the same battery would have made in July 2025, the benchmark's first month, so revenues are still climbing year-on-year even as they cooled through the summer.

Key takeaways

• In July 2026 a four-hour benchmark battery earned 1.67 million PLN/MW-year, a 9% decrease on June's revenues.
• aFRR up-reserve is an evening product. It cleared at 420 PLN/MW/h in the 20:00 to 24:00 block and fell below 90 at midday, where downward reserve takes over.
• Day-ahead spreads narrowed 19% to 714 PLN/MWh but stayed historically wide, so the battery kept most of its power in reserve and cycled less than once a day.

To learn more about the Polish benchmark, reach out to alex.kelham@modoenergy.com

The benchmark is one battery, priced against the real market

Poland has no asset-level data for utility-scale storage. PSE publishes system-wide balancing prices, volumes and activations, but never the schedule or settlement of an individual battery. Public data alone therefore cannot reconstruct what a real asset earns.

The benchmark is therefore simulated: Modo Energy runs a mixed-integer linear programme that optimises a representative 50 MW battery against real Polish prices across multiple durations, at 88% round-trip efficiency and two cycles a day.

The model solves each day in two steps that mirror the market. A day-ahead step sets FCR and aFRR capacity alongside the day-ahead energy position, and a second step settles aFRR activated energy once the first has locked those commitments in.

Modo Energy calibrates modelled revenues to 80% of the theoretical maximum, the same percent-of-perfect factor it uses across its benchmarks. Every figure here therefore already discounts the foresight, availability and execution gaps a real operator faces.

aFRR capacity is almost the entire revenue stack

In July 2026 aFRR capacity paid for 67% of a four-hour battery's revenue. Day-ahead energy added 24%, FCR 8%, and activated aFRR energy almost nothing.

New battery capacity connects every month, but each project spends months in prequalification before it can bid into aFRR, so the reserve stack stays tight and capacity prices are easing only gradually rather than falling outright.

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Revenues fell 9% in July as aFRR capacity cooled

The four-hour battery earned 1.67 million PLN/MW-year in July, down 9% from 1.84 million in June, and the two-hour fell the same 9%. Almost the entire 174,000 PLN drop came from aFRR capacity, which shed 103,000 PLN, and day-ahead revenues contracting by 78,000 PLN. FCR was the only market to grow.