Following the Hungarian record, construction of one of Europe’s largest energy storage facilities can begin

Following a milestone in Hungary, Greenvolt Power is preparing its next major energy storage project. On 10 June, the company commissioned Hungary’s largest battery-based electricity storage facility to date in the town of Buj, and is now set to begin construction of Poland’s largest facility of its kind.

The Szabolcs project consists of two units, each with a capacity of 49.9 MW and a storage capacity of 144.288 MWh, thereby supporting the flexibility of the domestic electricity system with a total capacity of 99.8 MW and a storage capacity of 288.576 MWh. BYD supplied the battery technology for the Hungarian project; the collaboration between the two companies is now continuing in Poland.

The Buji facility will be followed by a development on a European scale

Greenvolt Power has signed an agreement with BYD Energy Storage for the supply of battery energy storage systems to be built in Siedlce, Poland. The planned facility will have a capacity of 600 MW and a storage capacity of 2.4 GWh, which could make it Poland’s largest storage facility. Given its scale, it could also rank among the most significant electricity storage projects in Europe.
The scale of the development clearly illustrates how rapidly the role of battery energy storage is being recognised in the region. Whilst the Buji project set a new record in Hungary, the system planned for Siedlce is being developed with several times the capacity and will support the stability of the Polish electricity system as well as the further expansion of renewable energy sources.

The Polish system is due to be commissioned by the end of 2027

Construction of the battery energy storage facility in Siedlce is scheduled to begin in the third quarter of 2026, with Greenvolt Power planning to commission the facility by the end of 2027. The facility could help ensure more stable and flexible operation of the Polish electricity system, whilst supporting the further expansion of electricity from renewable sources in Poland and Central and Eastern Europe.

Hungary has also played a significant role in these developments

The role of battery energy storage systems is becoming increasingly important in Europe because the output of solar and wind power plants is weather-dependent. These storage systems are able to balance out fluctuations in generation: they draw electricity when there is a surplus of generation, and then feed it back into the grid when demand is higher.
According to the statement, this trend is also reflected in the decision taken by 22 Member States of the European Union on 26 June 2026 to commit to building a further 45 GW of energy storage capacity between 2026 and 2028. Hungary has also joined the agreement, committing to the construction of a further 700 MW of storage capacity in order to strengthen energy sovereignty and increase wind power generation capacity.

Our country is also a priority area for development

„Energy storage is a key factor in building more resilient and flexible electricity systems, whilst supporting the growth of energy generation from renewable sources,” said João Manso Neto, Chief Executive of the Greenvolt Group. He added that Greenvolt has built up a significant storage portfolio and is the developer of several of Europe’s largest battery energy storage projects.
Central and Eastern Europe is a key development region for Greenvolt Power. In Poland, the company’s development portfolio comprises 238 MW of wind power, 657 MW of solar power and 2,595 MW of battery energy storage capacity. In Hungary, the company has a total of 158 MW of solar power plant capacity and 135 MW of battery energy storage capacity.