Gasgoo Munich- CATL and Bulgarian renewable energy company Solarpro have signed an agreement covering 2 GWh of sodium-ion battery storage systems, expanding their existing partnership into an emerging alternative to lithium-based storage, according to a post CATL posted on July 21 via its WeChat account.Image source: CATLThe companies plan to begin deploying Central and Eastern Europe's first large-scale sodium-ion energy storage project by the end of this year. The project will use CATL's TENER Sodium system and provide an early test of the technology's commercial viability under European grid and climate conditions.According to CATL, TENER Sodium is designed to deliver as many as 15,000 charge-discharge cycles, supporting an operating life of approximately 25 to 30 years. The system is also engineered for cold climates, retaining 92% of its capacity at minus 20 degrees Celsius.That low-temperature performance could be particularly relevant in markets such as Lithuania and other parts of Eastern Europe, where winter temperatures can fall to between minus 15 and minus 20 degrees. Sodium-ion technology also uses more widely available raw materials than conventional lithium-ion batteries, offering potential benefits in cost stability and supply-chain diversification as production scales.CATL and Solarpro began working together in 2024 with the deployment of a 150-MWh EnerC+ liquid-cooled battery storage system in Bulgaria. Their cooperation expanded in May this year when a 602-MWh facility using CATL's lithium-based TENER system was connected to the Bulgarian power grid.Located in Burgas, the project is Bulgaria's largest operating battery storage facility and increased the country's total storage capacity by 10%, according to CATL. Solarpro was responsible for engineering, procurement, construction and system integration, while CATL supplied the storage technology.The latest agreement extends that relationship from established lithium-ion systems to sodium-ion technology, giving CATL a regional partner with experience integrating its products into Eastern European power networks.For CATL, the Solarpro agreement forms part of a broader effort to commercialize sodium-ion storage internationally. The company is positioning sodium-ion batteries alongside lithium-based systems rather than as an immediate replacement, with the two chemistries suited to different operating environments and project economics.The 2-GWh commitment gives the technology a pathway from product validation to utility-scale deployment in Europe. Its longer-term competitiveness, however, will depend on manufacturing costs, operating performance and whether sodium-ion systems can demonstrate attractive returns over their full service life.