CEZ Group battery in Ostrava, Czechia, stored more than 2,000 megawatt-hours of energy in a year

The CEZ Group battery system in Ostrava-Vítkovice, which was the most powerful facility of its kind in Czechia when it began operating last year, stored more than 2000 megawatt-hours of energy during its first year in operation. Its efficiency reached 87 percent. Vladislav Sobol, a company spokesperson, told the Czech News Agency.

The facility consists of 1360 battery modules and contains 90 tonnes of lithium. It has a capacity of ten megawatts. The system cost more than CZK 200 million to build and can deliver enough energy at once to cover the daily consumption of 1300 households.

“The system, which is managed remotely using software, provides what are known as balancing services to the Czech power grid. When the frequency in the grid falls below 50 hertz, the system automatically begins discharging and supplies balancing energy to the grid within milliseconds. Conversely, if the grid frequency rises above 50 hertz, the battery helps absorb power from the grid by charging,” Sobol said.

The system is operated by ČEZ Energo, part of the ČEZ ESCO group. ČEZ Energo CEO Martin Václavek said that its first year of operation had confirmed that the battery system, combined with gas units, could reliably regulate grid frequency automatically.

“The battery’s operating-cycle efficiency reached 87 percent, and the facility has so far stored a total of more than 2000 megawatt-hours of energy. The system has proved itself across a wide range of battery capacity use, from five to 95 percent. We have also tested the battery operating independently of gas sources in so-called standalone mode,” Václavek said.

Experience to date has also shown that the battery responds better to larger frequency fluctuations in the grid when operating with its state of charge at around half its capacity and when charging or discharging more frequently in a coordinated manner. The battery has also received an additional certification confirming that it can provide balancing services automatically and immediately when an imbalance occurs in the grid.

“The Czech energy sector is changing, and alongside new renewable power plants it also needs to expand the capacity of reliable backup sources. After a year of operation, we can include the Vítkovice battery in this category too: it has demonstrated its full ability to provide ancillary services for ČEPS. This is mainly about being able to supply the power missing from the grid within milliseconds and stabilise its frequency and other electricity quality parameters,” said Kamil Čermák, CEO of ČEZ ESCO.