To provide a portfolio performance view that is neutral to asset availability, we introduced methodological updates. Firstly, it applies a data-quality filter to exclude days where an asset was not operational for more than four hours. As a result, revenues from wholesale, aFRR, and FCR on these partial-availability days are removed, which can lead to slightly lower total revenues. However, the same filtering is also applied to the calculation of average marketable power (MW) and energy (MWh), meaning that averages are computed only on fully operational days. This creates a more representative performance metric.
Secondly, duration clustering has been refined. The 2h segment is now defined as 1.51-2.5h rather than extending to 3.5h. This change was requested by asset owners and market participants to create a cleaner benchmark that more closely represents a true 2h asset. The cluster description now also focuses on P10/P90 ranges rather than minimum/maximum values, reducing the influence of outliers.
However, when adjusting for these composition effects, the underlying performance remained nearly identical, confirming that the new methodology improves consistency and robustness rather than materially changing economic outcomes.
For the 1.51-2.5h BESS portfolio in Germany, annualized PnL increased from EUR 180,795.30 per marketable MW in March to EUR 257,383.45 in April (+42.4%). Average daily cycling rose from 1.39 to 1.42 FCE/day. For the 0.9-1.5h BESS portfolio in Germany, annualized PnL increased from EUR 136,496.87 per marketable MW in March to EUR 180,345.68 in April (+32.1%). Average daily cycling was broadly stable at 1.08 FCE/day.
April extended the March recovery rather than reversing it. The uplift was no longer driven by higher outright wholesale prices: Average day-ahead and intraday reference prices fell month-on-month. Instead, realized battery revenues were supported by stronger reserve capacity prices, higher aFRR energy monetization, and wider intraday dispersion linked to high solar output, low wind, and lower system demand.
| Category | Metric | March 2026 | April 2026 | MoM (month-on-month) |
| Market | aFRR capacity revenue (daily avg - EUR/MW) | 3,071 | 3,493 | +13.7% |
| Market | aFRR energy revenue (daily avg - EUR/MW) | 272 | 554 | +103.4% |
| Market | Day-ahead price (EUR/MW) | 99.25 | 78.52 | -20.9% |
| Market | ID VWAP (EUR/MWh) | 98.80 | 79.79 | -19.2% |
| Market | ID auction 1 (EUR/MWh) | 98.78 | 78.32 | -20.7% |
| Market | ID auction 2 (EUR/MWh) | 97.44 | 75.79 | -22.2% |
| Market | ID auction 3 (EUR/MWh) | 103.63 | 59.25 | -42.8% |
| Fundamentals | Average load (MW) | 54,655 | 51,188 | -6.3% |
| Fundamentals | Average solar generation (MW) | 9,786 | 13,423 | +37.2% |
| Fundamentals | Wind generation, average (MW) | 2,956 | 2,602 | -12.0% |
| Category | Metric | March 2026 | April 2026 | MoM |
| Portfolio (0.9-1.5h) |
PnL (EUR/MW/year) | 136,497 | 180,346 | +32.1% |
| Portfolio (0.9-1.5h) |
Cycles (FCE/day) | 1.09 | 1.08 | -0.9% |
| Portfolio (0.9-1.5h) |
Average duration per day (h) | 1.20 | 1.17 | -2.5% |
| Portfolio (1.51-2.5h) |
PnL (EUR/MW/year) | 180,795 | 257,383 | +42.4% |
| Portfolio (1.51-2.5h) |
Cycles (FCE/day) | 1.39 | 1.42 | +2.2% |
| Portfolio (1.51-2.5h) |
Average duration per day (h) | 2.09 | 2.06 | -1.4% |
Wholesale price levels weakened in April even as battery revenue remained strong. The average German day-ahead price declined from EUR 99.25/MWh in March to EUR 78.52/MWh in April (-20.9%). ID VWAP (Intraday volume-weighted average price) declined from EUR 98.80/MWh to EUR 79.79/MWh (-19.2%). The sharpest move was in ID auction 3, which fell from EUR 103.63/MWh to EUR 59.25/MWh (-42.8%).
However, price dispersion improved. A simple daily spread proxy across day-ahead, ID VWAP, and ID auction references increased from EUR 20.70/MWh in March to EUR 25.64/MWh in April (+23.9%). The maximum daily proxy widened to EUR 95.52/MWh on 2026-04-25, confirming that the month contained deeper short-term dislocations despite lower average price levels.
The balancing complex was again the main source of support. Average daily aFRR capacity revenue increased from EUR 3,071/MW/day in March to EUR 3,493/MW/day in April (+13.7%). Average daily energy arbitrages revenue increased from EUR 272/MW/day to EUR 554/MW/day (+103.4%), making activation energy a much larger contributor than in March.
At the product level, aFRR up capacity prices increased from EUR/MW/day 10.27 to 11.16 (+8.6%), aFRR down capacity increased from EUR/MW/day 11.83 to 20.47 (+73.1%), and FCR capacity increased from EUR/MW/day 16.64 to EUR 22.95 (+37.9%).
The stronger April revenue profile was mainly linked to structural changes in renewable generation and system balance. Wind generation remained relatively subdued during several high-value periods, tightening the system and increasing scarcity in the balancing market. At the same time, solar output increased materially versus March, creating deeper midday price depressions followed by steeper evening ramps. This widened intraday spreads and improved arbitrage opportunities for BESS assets.
The exceptional peak on 26 April was likely driven by a combination of low residual load flexibility, sharp renewable ramps, and elevated reserve-capacity prices. High solar penetration during daytime hours compressed midday prices, while weaker wind and stronger evening demand recovery generated significant upward price corrections later in the day. These conditions typically increase both wholesale spread capture and ancillary-service revenues simultaneously.
Fundamentals shifted further into a spring solar regime. Average solar generation increased from 9,664 MW in March to 13,367 MW in April (+38.3%), while average wind generation fell from 3,118 MW to 2,535 MW (-18.7%). Average load declined from 54,335 MW to 51,379 MW (-5.4%).
The combination of materially higher solar, lower wind, and lower demand created deeper daytime charging opportunities and steeper residual-load ramps. Lower wind also supported reserve scarcity conditions. The result was a market environment in which average wholesale prices fell, but batteries still captured stronger spread, balancing, and reserve monetization opportunities.