A 2-hour BESS with a full grid connection in the Netherlands earned €305k/MW/yr over the first nine months of 2026.

Each additional hour of duration adds less revenue than the one before. Going from 1 to 2 hours adds the most, €92k/MW/yr, because it unlocks upward aFRR capacity, the largest revenue stream for a 2-hour battery. A 1-hour battery has too little stored energy to guarantee its aFRR obligation.

Beyond 2 hours, the extra duration goes into day-ahead trading instead. A longer battery captures more value in each cycle, so a MW used for trading comes close to what the same MW earns held in aFRR capacity.

Key takeaways

• Adding duration pays less with every hour, from €92k/MW/yr going from 1 to 2 hours down to €14k going from 3 to 4 hours, so revenue per MWh of BESS capacity falls from €213k to €89k.
• Wholesale trading revenue is rising because higher gas prices widened day-ahead spreads from April 2026. Day-ahead trading paid a 4-hour battery €116k/MW/yr in 2026, against €26k across 2025.
• Without FCR and aFRR capacity payments, a 4-hour battery keeps 74% of its 2026 revenue, against 62% for a 2-hour one, because more of its revenue comes from wholesale trading.

Why does each duration increase pay less than the last?

Going from 1 to 2 hours almost triples the aFRR capacity a battery can sell: on average 7 MW on a 10 MW / 2-hour battery, against 2.6 MW on a 1-hour battery. aFRR capacity is paid per MW, but every MW has to be backed by energy in the battery. For shorter durations, the benchmark reduces the aFRR capacity a battery can sell. Every MW of upward aFRR needs enough charge to deliver, and every MW of downward aFRR needs enough empty space to absorb.