The BigBattery storage systems

With BigBattery Lausitz, we have been operating one of Germany's largest battery storage facilities since 2020. With 54 MWh of usable storage capacity, the facility at the Schwarze Pumpe site (Brandenburg) combined modern power plant infrastructure with battery storage technology at a new scale at the time. The project, with an investment volume of around €25 million, was funded by the state of Brandenburg.

The BigBattery, based on lithium-ion technology, enhances the flexibility of power supply. The charging and discharging of the battery modules is aligned with conditions in the power grid and the electricity markets. 

Within this framework, BigBattery Lausitz has been reliably providing balancing energy since December 2020. It is used to maintain the frequency in the power grid within the technically required range of 50 hertz. By quickly absorbing and releasing electricity over limited periods of time, BigBattery Lausitz helps to keep power generation and consumption in balance.

Facts and figures

The BigBattery Lausitz is located in the immediate vicinity of the Schwarze Pumpe power station. Covering an area of 110 by 62 metres, 13 containers house 8,840 battery modules. In addition, there are 13 converter containers, a block transformer and switchgear for medium and low voltage. Equally important are the battery and energy management system and the storage-internal control, protection and fire alarm technology.

The battery storage facility is connected to the grid at the high-voltage level (110 kilovolts). This also provides a connection to the extra-high-voltage grid on site.

A second BigBattery with a storage capacity of 137 MWh is currently being built at the Boxberg energy site in the Oberlausitz region (Saxony). It is based on modern lithium iron phosphate batteries.

Facts and figures

Compared to the BigBattery Lausitz, the BigBattery Oberlausitz will have two separately controllable storage strings (50 MW each). It will therefore also have two grid connection points at the 110kV switchgear of the Boxberg power plant and two block transformers. Both strings can back each other up when providing balancing energy, but can also be used in parallel for different applications. This also expands the possible range of applications (primary and secondary balancing power, short-term energy trading).

Unlike the BigBattery Lausitz in Schwarze Pumpe, which has a total of 13 battery containers measuring twelve metres in length, over 400 smaller, compact containers with pre-installed battery modules will be installed in Boxberg. Lithium iron phosphate accumulators will be used. Their main advantages lie in their cycle stability. The batteries have an improved service life for the intended operating conditions and require less space.

The balance between electricity generation and consumption is necessary to prevent supply disruptions and, in the worst case, widespread power outages. Fluctuations affect the frequency of the electricity, which must always be kept within the range of 50 hertz.

Transmission system operators maintain different types of so-called balancing reserves for this purpose. This energy comes from flexibly controllable systems such as batteries and power plants. The rapid deployment of balancing energy compensates for unforeseen fluctuations and ensures stable power grid operation.

• If electricity generation temporarily exceeds demand, negative balancing energy is required. During such periods, batteries can be charged to increase electricity consumption and restore system balance.
• Positive balancing energy is used when there is an unexpected increase in demand for electricity that exceeds the amount currently available. In this case, additional electricity suppliers are activated at short notice. Batteries can also supply stored electricity during this periods.

The various types of balancing energy differ in terms of their provision time and duration. Primary balancing power must be fully available within 30 seconds and usable for a period of five minutes. Secondary balancing power follows within five minutes and the minute reserve within 15 minutes.

Most of this balancing energy currently comes from conventional power plants, as it must be available with absolute reliability, regardless of wind and sun. Alternative solutions are needed here in the course of the energy transition. Battery storage systems such as LEAG's BigBatteries are a key technology.