Deutsche Version  ACT
Electrical Storage
Grids 18.10.2016

Transformer station of Energiequelle GmbH at site Feldheim
© Energiequelle GmbH

Grid stabilization using battery power plants

How can a battery storage system be further developed to form a plant for balancing power production? This is the question that the researchers are investigating in the SDL-Batt project. Here they are testing various system services and evaluating them in economic terms, whereby the research is focusing on the operating data, energy balancing and the simulation of different methods.

Project status Capture and evaluate operating data
Efficiency AC/AC > 85 %
Typical system size Energy 10,7 MWh
Typical system size Output 10 MW
Service life of the system approx. 20 years
Typical discharge time 60 min
Response time when preparing the energy < 1 s
Typical period between storage and withdrawal 1 s - 10 min
Example application areas primary control energy
Project duration March 2013 until August 2017

The development of a highly efficient battery storage as a power plant for control energy and to provide grid stabilization services is the focus of the joint research project. The aim is to test various system services, document their performance and compare them regarding their economic feasibility. The provision of control power and other ancillary services as well as the necessary development and testing are considered on the basis of an innovative 10 MW lithium-ion battery system. Operating data, accounting, legal and regulatory constraints and simulation of different control strategies are the focus of this study.

  • Project team stuff at BTU Cottbus during work. &copy; BTU Cottbus
  • Studies on the battery-stress by cycles and aging in the laboratory of the chair of Power Plant Technology &copy; BTU Cottbus
  • Measuring computer with software for conducting and evaluating the single-cell experiments &copy; M. Nimtz
  • Battery test station at the Chair of Power Plant Technology, BTU Cottbus-Senftenberg &copy; M. Nimtz
  • Controllers and Electronic Loads of battery test stand &copy; M. Nimtz
  • Model of the building for the 10 MW battery, Energiequelle GmbH &copy; Energiequelle GmbH
  • Display of grid frequency at 50Hertz Transmission GmbH &copy; 2013 50Hertz Transmission GmbH
  • Diagramm cycle energy in primary control mode &copy; BTU Cottbus
  • Measuring station for Li-ion single cells &copy; M. Nimtz

Theoretical foundations ancilliary services and tests of the battery storage

The project was started in early March, 2013, the first half of the project was on the theoretical foundations of ancillary services provided by lithium-ion cells. Ongoing work includes the political and legal frameworks for battery storage power plants in the national and European context. Furthermore, theoretical operating simulations for various applications of electricity storage and the provision of ancillary services are created. The studies of the potential, of market and grid integration have already been started.
The planning and construction of a 10 MW power plant by the operator  Energiequelle GmbH is going on in parallel, and will lead to commissioning of the storage center  in mid 2015. The construction of the battery power plant also represents the major milestone of the project. After commissioning, the theoretical investigations can be specified by experimental test data and commercial operation data. The energy balance of the battery storage and its performance is studied in detail subsequently, particularly in the way in which the primary control energy is provided.

In addition to the tests at the battery storage plant, experimental tests at single lithium ion cells will with regard to power output and ageing  for micro-cycle (low power, low DoD, fast cycles) will be done. These micro cycles are characteristic of primary control energy operation. Therefore, single lithium ion cells are tested under long-term load tests at a battery test rig at the Brandenburg University of Technology Cottbus-Senftenberg and their parameter trends are evaluated. The goal is to give an operational data based life time prediction. The total project duration is three years.

Project context

Given the increasing feed-in of electricity from renewable energy sources (RES), battery systems are essential for balancing production and demand.

The provision of ancillary services in conventional power plant units leads to a "must-run" (high minimum operating point without further potential of lowering feed-in power) of these systems, resulting in a system conflict in phases of high RES feed-in. Therefore, non-conventional providers of ancillary services such as the projected battery power station are an alternative to solve this problem.

In this joint project,  the stationary demonstration storage battery is a 10 MW unit. It is installed at the self-sufficient community Feldheim (Brandenburg) by the operator Energiequelle GmbH. The investment costs are not part of the project SDL Batt. The capacity of the "regional balancing energy power plant" (german abbreviation: RRKW) within the joint project  is expected to be 5 MWh. The configured storage efficiency is about 90% for the overall battery system with inverter.

Research focus

The RRKW Feldheim consists of four main components: the 10 MW energy storage, a highly innovative conversion system for connecting to the network, the overall smart energy management and the interface to the transmission network of 50 Hertz Transmission GmbH. An important part of the collaborative research project is to study and test the real provision of system services with a focus on balancing energy supply. The 10 MW power class is unique in Germany.

The optimization potential regarding specifically the objectives of the project will be investigated in the field of energy optimization (effectiveness, efficiency), economic optimization (cost, market ability) as well as dimensioning and design of the system in terms of performance and capacity for the different applications.

Economic viability and durability

Primary control is the most feasible application of the proposed battery power station on the threshold of profitability.  However, the balancing energy market is a highly volatile market, so that forecasts are very uncertain. As part of the project results, an optimized design in conjunction with gained operating experience and future higher lots will reduce costs of the overall system.

By functioning as a pure system service power plant without minimum operatin point such as conventinal power plants, the 100% control energy operation of the battery storage contributes to a cost-efficient system conversion in the context of energy policy.


The BTU has developed knowledge on the topic of "ancillary services in the energy supply system of the future" through active research and a variety of solutions through relevant scientific contributions. The focus of this research lies in the areas of the regulatory framework of the energy and balancing power market, and in the operational data and simulation.

With this research project, the Energiequelle GmbH intends to investigate the technical and economic possibilities of battery storage, as an additional supplier of ancillary services, combined with fluctuating power plants (wind farms, photovoltaic systems)or as stand-alone solution, in order to develop new business models.

The 50 Hertz Transmission GmbH is mainly active in the areas of market modeling and the technical and organizational integration of the battery storage into the transmission network. In addition, 50Hertz brings extensive expertise on market conditions for system services as well as for grid modeling to the project.

Supported by: The Federal Government on the basis of a decision by the German Bundestag


no news in this list.


Other Addresses


Research funding

The information system EnArgus provides information on research funding, including on this project (German only).