Enervis Battery Storage Index: Revenues reach record level in May 2025
Since the first quarter of 2025, at Enervis, we have been publishing a monthly Battery Storage Index based on historical market data. The first publication of the index was presented in an initial article in March 2025. The index illustrates revenue opportunities for battery storage systems by accounting for participation in both the intraday and balancing power markets. It provides an overview of achievable revenues for each of the past 13 months.
New revenue figures for May 2025
In May 2025, achievable revenues continued to rise, reaching approximately €19,100 per megawatt. This represents an increase of around 27% compared to April and is 22% above the estimated revenues for May 2024. May 2025 thus marks the highest monthly value since the beginning of the observation period in January 2024. None of the previous months reached comparable levels. Following the record-setting figures in April, PV generation once again reached historic highs in May. The significant expansion of installed PV capacity is now clearly reflected in the data. The high feed-in volumes led to a large number of hours with negative prices and correspondingly high price spreads in both the day-ahead and intraday markets. At the same time, prices for Frequency Containment Reserve (FCR) and automatic Frequency Restoration Reserve (aFRR) continued their upward trend and remained at a comparatively high level. These market conditions are the main drivers behind the increase in revenues observed in our calculations.
General trends
The monthly achievable revenues have fluctuated significantly over the past 13 months. They ranged from a low of €6,770 per megawatt per month in February 2025 to a peak of €19,100 per megawatt per month, reached in May 2025. Revenues tend to be higher during the summer months, largely due to strong PV generation combined with relatively low overall electricity demand. In addition, conventional generation capacity is typically lower during summer, partly because of scheduled maintenance and, in the case of gas-fired power plants, potentially reduced efficiency under high ambient temperatures. Wind generation availability also tends to decline in summer compared to autumn and winter. As a result, short-term fluctuations or forecast errors in PV feed-in lead to increased market volatility during these months reflected in more dynamic activity on the intraday market. This seasonal pattern is not unique to Germany and can be observed in other markets as well. On average, battery storage systems generated almost €12,900 per megawatt per month in the last twelve months, amounting to approximately €155,000 per megawatt annually.
Current Expected Revenues 2025
In line with the historical methodology, the Enervis Battery Storage Index also provides a forward-looking view of revenue expectations for the current year. Based on Enervis’ latest electricity price forecasts for the intraday and balancing power markets, the operation of a typical standalone battery storage system in 2025 has been modelled.
The achievable revenues for the full year 2025 are still based on our Current Efforts Scenario Q2/2025; no update to the scenario was made this month. The currently projected revenues amount to €147,800/MW/year.
The projected revenues for 2025 remain slightly below the average achievable revenues of the past twelve months, at €147,800/MW/year. However, they are still within the same order of magnitude as shown in the Enervis Battery Storage Index. The storage parameters have remained unchanged.
Methodological explanation: The Enervis Battery Storage Index shows the monthly net revenues that can be achieved historically and in the future in Germany for a 1 megawatt capacity and 2 megawatt hours storage volume (2 hours) battery storage system. The storage system was modeled with a use restriction of 1.5 cycles per day, a maximal depth of discharge of 90%, a technical availability of 97% and a round-trip efficiency of 87%. The index takes into account participation in the following markets: Intraday, Frequency Containment Reserve (FCR) and automatic Frequency Restoration Reserve (aFRR). Imperfect foresight and no revenues from aFRR energy are modeled. The respective prices of the markets for the historical analysis are taken from publications of the transmission system operators and EPEX-Spot. The future outlook is based on the same modeling and parameters and prices from the current Enervis power price scenario Current Efforts Q2/2025.
Further information:
If you are interested in a more detailed analysis and the full report, you can request it here.
Authors:
Mirko Schlossarczyk – Managing Director of enervis energy advisors is an experienced energy market expert. His consulting focus is on electricity price forecasts, electricity market scenarios and the asset valuation of BESS.
Jonas Anthonioz – Consultant at the energy economics consultancy enervis energy advisors, where he is responsible for battery storage-related topics. In addition to his usual tasks in revenue assessment and profitability analysis of battery storage projects, he developed the enervis BESS Index and the associated BESS Index Report.
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