300 MW: Next Kraftwerke and ECO STOR sign Tolling Agreement for Germany's largest Battery Storage Facility

Next Kraftwerke will deploy the first of three storage units in the day-ahead, intraday, and balancing power markets starting in November 2026. Two additional units will be added gradually. Once fully operational over the course of the next year the storage facility will have a capacity of 300 MW and over 700 MWh.

The storage system responds to price and grid signals. It stores electricity during periods of high generation and/or low demand, and discharges during periods of low generation and/or high demand. In addition, the storage system compensates for frequency fluctuations and short-term grid imbalances. Furthermore, it provides reactive power, which is required to maintain voltage in the grid. The facility is designed to handle two full charging and discharging cycles per day and, based on calculations, can supply electricity to approximately 500,000 households for two hours or 100,000 households for ten hours. In the critical event of a power outage, the storage system is capable of autonomously restoring the power supply.  

Innovation for a stable energy system

“With the tolling model, we are establishing a new standard in storage marketing and creating reliable framework conditions for our partners. We are demonstrating how state-of-the-art optimisation algorithms and intelligent market integration work together,” explains Marc Rühs, CEO of Next Kraftwerke. "In combination with our expertise in short-term optimisation and operational marketing, we complement each other perfectly with Shell Energy Europe as a partner for long-term hedging and risk management. We enable optimal market participation and make an important contribution to grid stability."

Georg Gallmetzer, Managing Director of ECO STOR, emphasises: “Our focus is on combining technological innovation with clearly defined operational guidelines. By consistently taking grid requirements such as ramping speeds and the provision of control reserves into account, we ensure grid-friendly and market-oriented operation. This allows us to combine maximum flexibility with operational reliability. The combination of Next Kraftwerke and Shell gives us the security we need for projects of this magnitude. Our partnership with Next Kraftwerke and Shell gives us the necessary confidence that projects of this scale require. We also want this collaboration to be seen as a sign that the market is already far ahead of policy and regulation. We are making the energy transition irreversible, and with the storage project in Förderstedt, we are once again taking a major step forward.”

Tolling as a catalyst for market-oriented storage marketing

The contract model combines a tolling agreement for 80 percent of the battery capacity with flexible, market-price-based remuneration (merchant) for the remaining 20 percent. In return, Next Kraftwerke receives full flexibility to deploy the battery across all markets including the day-ahead, intraday, and balancing power markets. It is precisely this combination that is crucial in making large-scale battery storage systems financially viable for banks and investors today. Next Kraftwerke has been successfully marketing Battery energy storage systems (BESS) since 2018, both in the highly dynamic balancing energy market and in spot markets.

Stable marketing models as a response to regulatory uncertainty

This is becoming increasingly important against the backdrop of the current energy policy debate. Unresolved regulatory issues and mixed market signals continue to lead to increased uncertainty in the market and higher financing requirements for storage projects. In this environment, structured marketing models with clear risk distribution create the necessary stability for investment decisions. Through this agreement, ECO STOR and Next Kraftwerke are therefore sending a clear signal: even under challenging regulatory conditions, large-scale battery storage facilities can be structured in an economically viable manner.

Flexible grid connection accelerates project start

ECO STOR has concluded flexible grid connection agreements with the grid operator 50 Hertz. Next Kraftwerke incorporates restrictions such as ramp limits (the rate at which power output can be increased) and ancillary service limits (the maximum amount of ancillary services) into its operational optimisation process, thereby ensuring cost-effective operation. Large-scale battery storage systems are thus increasingly evolving from opportunity-driven individual projects to an independent, investable infrastructure class. Förderstedt represents not just a single project, but another step toward a more flexible, resilient, and market-based energy system in Germany.