What would a battery have earned in Spain? Introducing the ME BESS ES benchmark
What would a battery have earned in Spain? Introducing the ME BESS ES benchmark
The ME BESS ES benchmark closes that gap. Now live on the Modo Energy Terminal, the ME BESS ES benchmark simulates a battery cross-optimised across Spain's energy and ancillary markets. It refreshes daily with real prices.
Key takeaways
- The ME BESS ES is live on the Terminal as a neutral 4h, 2h, 1h benchmark, with 88% round-trip efficiency and 2.0 cycles per day.
- From mid-2025, mFRR and technical restrictions phase II (TTRR P2) show a revenue gap over an aFRR-only ancillary strategy, peaking in June and August 2025.
- The battery discharges at above-average prices: around €90/MWh, as captured in the day-ahead market in 2025, 50% above the €60/MWh market average.
To learn more about the Spanish benchmark, reach out to the team: pablo@modoenergy.com and paulo@modoenergy.com.
Why does the Spanish market need a benchmark?
Every liquid commodity market has a working benchmark. Battery energy storage in Spain has not had a single, reliable, transparent source of truth until now. A neutral, market-wide reference enables participants to do four things:
- Track where revenues are going. Owners, investors, and offtakers can see whether the market is expanding or contracting, independently of any individual asset's performance.
- Benchmark optimiser performance. A transparent potential number lets owners hold optimisers to account against an independent reference rather than each provider's own framework.
- Settle liquidated damages. Some unavailability contracts reference a market rate; without one, disputes drift to court.
- Settle route-to-market and virtual contracts. Index-linked PPAs, floors, and swap structures need a transparent settlement reference.
Modo Energy’s benchmark closes this gap with a neutral number and an open, transparent methodology that makes all market parties comfortable with the values used in these contracts.
How did we backtest the benchmark?
We ran a standalone 50 MW / 4h battery (200 MWh) on real Spanish prices from January 2024 to June 2026. The specification matches the median utility-scale project in Spain's connection queue.
The model runs the same battery through three cumulative configurations. First, day-ahead plus intraday: OMIE (Operador del Mercado Ibérico de Energía) energy markets only. Second, adding real-time rebalancing plus aFRR capacity (Banda Secundaria) and aFRR activated energy (aFRRE). Third, all markets: adding mFRR and TTRR P2, up and down.
Three modelling choices keep the output honest. The model encodes prequalification rules, so minimum bid sizes, activation prices, and energy reservation requirements bind the schedule as in real operations. Foresight is limited: the model solves day-ahead, intraday, and real-time sequentially, and positions locked at each gate cannot be unwound. The intraday and real-time steps re-optimise over 2-hour rolling windows. Granularity follows each market's reform timeline, moving from hourly to 15-minute pricing as OMIE reformed intraday (March 2025) and day-ahead (October 2025).
Finally, we apply no post-hoc calibration factor. Public per-asset revenue disclosure in Spain is too sparse to serve as an anchor. Instead, we validate the day-ahead sub-line against publicly available Iberian BESS TBx benchmarks (~€80k/MW for 2024; ~€130k/MW for 2025).
Ancillary services widen the revenue gap from mid-2025
Going beyond day-ahead and intraday adds revenue for a Spanish battery in every month of the backtest.
In 2024, aFRR did most of that work. The aFRR and all-markets lines track each other closely, sitting well above energy-only optimisation.
Then the lines split. The all-markets configuration pulls away, peaking in June and August 2025, as the model finds additional value in mFRR and technical restrictions. That value was hard to reach in 2024: Spain's mFRR market only connected to the European MARI platform in December 2024. For operators, the Spanish revenue stack is broadening, and prequalifying for additional markets is increasingly valuable.
Day-ahead carries the 2026 stack
The day-ahead market spread has increased throughout 2026. Additionally, market participants continue to find opportunities to optimise battery participation between the day-ahead market and Technical Restrictions Phase 2 downwards, increasing their overall day-ahead market revenues.
