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Electrical Storage
M5BAT battery storage power plant 28.7.2016

Die Visualisierung zeigt die obere Südansicht des Batteriespeicherkraftwerks M5BAT.
© Uniper

Battery storage system with five megawatts of capacity

Researchers at RWTH Aachen seek credible answers on the costs and savings potential of battery storage power plants together with industry partners. A modular battery storage power plant, unique worldwide, with five megawatts of capacity is currently being developed for this purpose.

Project status Test phase
Typical plant size (energy) Approx. 4 MWh
Typical plant size (output) 5 MW
Storage loss Approx. 0.1%/day
Service life of the plant Up to 20 years, depending on technology
Response time on supplying energy Approx. 100 ms
Efficiency (AC/AC) Subject to application and battery type approx. 90%
Cycle durability Subject to application and battery type up to 10,000
Typical discharge time 45 to 60 minutes
Typical period between storage and withdrawal Heavily application-dependent – from seconds to several hours
Application examples Integration of renewable energy, balancing power, power trading
Project duration July 2013 until June 2017

The special feature of the M5BAT is the modular structure of the medium-voltage storage system, which interconnects different battery technologies. M5BAT stands for “modular multi-megawatt multi-technology medium-voltage battery storage system“. Lithium-ion batteries are used as short-term power storage units, energy is supplied by high-temperature batteries over several hours and lead acid batteries are used for short and medium discharge times.

Technical and economic optimisation potential is identified by the researchers during construction and operation of the plant. Target cost estimates for storage system applications, such as primary and secondary control, are furthermore produced by the researchers. This allows for conclusive information on the revenue thresholds from which battery storage power plants can be economically operated, in due consideration of economies of scale, particularly with respect to battery cells, or on regulatory incentives that need to be created. The results are subsequently summarised in a manual for battery storage power plants, which is intended to be used for cost planning and for operating battery storage power plants.

  • East view © Uniper
  • The special feature of the M5BAT is the modular structure of the medium-voltage storage system, which interconnects different battery technologies. © Uniper
  • M5BAT stands for “modular multi-megawatt multi-technology medium-voltage battery storage system“ © Uniper
  • South view of the M5BAT building © Uniper

Further optimisation of battery power plant during operation

Construction and operation of the plant is intended to produce conclusive data on service life, costs and savings potential. This, above all, also includes peripheries for installation of the battery plant in addition to the actual costs for the battery cell. In addition to the housing, these also include battery management and battery diagnostics systems, the central plant controller and thermal management. The researchers test and optimise the interaction of the different battery types for various application profiles. The researchers furthermore hope to develop an energy management system for the plant encompassing the batteries, inverters and control system.

Battery storage systems enjoy universal application

Electrochemical storage devices enjoy trade appeal due to their independence of geographic constraints, as common with compressed air storage units and pumped storage power plants, and because relatively short planning terms are typically associated with their installation. It is therefore necessary to build expertise in the development of low-cost designs, in optimising operation and in conducting comparative technological analyses and to test the performance capability of various technologies under realistic operational conditions, unbiased as to the result.

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


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Research funding

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