Enervis BESS Index: What revenues can and could be achieved with large battery storage systems in Germany

Large-scale battery energy storage systems (BESS) are booming in Germany – and yet the market is only at the beginning of an enormous growth cycle.

The high number of grid connection requests and the urgent need and demand for flexibility in an energy system characterized by increasing volatility are clear proof of this. At the same time, business models based around standalone BESS are extremely economical and generate attractive returns. And this is without the need of state subsidies such as the EEG.

As a result, the relevant markets for BESS are coming more into focus. The intraday market in particular has created a veritable gold-rush atmosphere and high arbitrage profits over the past two years, with astronomical price spreads in some cases.

However, it is not easy to answer questions about future robust revenue levels or revenue ranges in a market that is still in its infancy. Possible regulatory measures and interventions, technical developments, falling investment costs, financial uncertainty, but also growing competition in this space are potential risks. The market is nascent and very dynamic, so reliable revenue-side empirical values or marketing patterns are hardly established. At this point, it is worth taking a look in the rear-view mirror: how have revenues developed in the recent past and what conclusions can be drawn from this?

Currently, the actual revenue levels achieved from BESS are quite opaque and often a well-kept secret of project developers, operators, and traders. In addition, due to the lack of secure (and transparent) subsidies, battery revenues are highly dependent on the market and therefore there is an additional intransparency with regard to realized and achievable BESS project revenues.

Therefore, the first battery storage benchmarks and indexes have already been published in recent months, primarily by BESS optimizers. These are intended to ensure greater transparency and traceability of revenue opportunities. However, these benchmarks understandably also focus on the performance of an optimizer’s algorithm. It is therefore difficult to compare various indexes.

On the other hand, Enervis, as a consulting company, intends to publish a monthly BESS index from the first quarter of 2025 onwards. Based on historical market data and using the tried-and-tested Enervis deployment optimization tool for BESS, the index will map historical revenue opportunities for battery storage systems on a monthly basis.

For a typical standalone battery storage system, participation in both the intraday market and the balancing power markets is taken into account. The model determines the achievable revenues for each month of the past thirteen months on the basis of historical market prices.

The monthly achievable revenues fluctuated considerably in 2024. The maximum was reached in June 2024 at just under EUR 18,000/MW/month, while the minimum was EUR 5,800/MW/month in February. Battery revenues tended to be highest in summer – the months with very high photovoltaic generation and low overall electricity demand.

A large proportion of conventional generation capacity is not connected to the grid in the summer months for seasonal reasons and the availability of wind energy is significantly lower than in the winter or fall months. As a result, short-term feed-in fluctuations or forecast deviations in photovoltaic feed-in in the summer months directly lead to greater volatility in the system.

This is directly reflected in a higher short-term demand for balancing energy or more intensive trading on the intraday market. The lack of generation from photovoltaic systems is then compensated with significantly more expensive power plants, which is reflected in high electricity prices, spreads, and revenues for battery storage. This is a pattern that can also be observed in other countries.

Over the past twelve months, BESS revenues have averaged just under EUR 12,000/MW/month (around EUR 144,000/MW/year).

The first two months of 2025 show a similar trend to 2024: low battery storage revenues with only around EUR 5,000/MW/month in potential revenues in February. This can essentially be explained by less volatility in various markets and comparatively low renewable energy generation. The average of the last 12 months shown is therefore slightly lower than the average for 2024 as a whole and stands around EUR 142,000/MW.

Similar to the historical approach, the Enervis Battery Storage Index also offers a look ahead to the current year. The use of a typical standalone storage system in 2025 is modeled based on our current power price forecasts from the first quarter of 2025 for the intraday and balancing power market.

The currently forecast revenue for 2025 as a whole is slightly lower than the average Enervis Battery Storage Index for 2024. With identical storage parameters, the forecast revenue for this year is EUR 134,000/MW/year.

About the 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.