Renewable power manufacturer WEG has supplied a battery energy storage system (BESS) with 4 MW of power and 8 MWh of capacity to Finland’s Callio solar park.
The project is one of the country’s first hybrid renewable energy projects combining large-scale solar generation with battery storage.
It was delivered in April 2026, to Solarigo Systems Oy, the investor and operator of the hybrid park located in Pyhäsalmi mine, a site that is being decommissioned and prepared to host new businesses focused on research, development and sustainable energy solutions.
Commercial power production at the Callio solar park began in June 2025, with the energy storage equipment maximising the capacity of the existing 13 MWp peak-power solar plant in its role of participating in electricity grid markets.
By enabling the storage of the energy generated by the photovoltaic plant, WEG BESS provides flexibility to the hybrid plant regarding the timing of energy export to the grid.
The project represents one of the first hybrid systems in Finland that combines photovoltaic generation with energy storage. The equipment supplied by WEG includes two battery containers totalling 8,360 kWh of capacity, a 4,400 kVA bidirectional power converter, a 4,500 kVA medium-voltage/low-voltage oil transformer and a central control system for the BESS set and the existing solar plant.
Manfred Peter Johann, Vice President of Automation & Systems at WEG, said:
“With WEG’s energy storage system integrated into the Callio initiative, we are helping to transform a historic mine into an innovation hub for renewable generation and storage.
“While at the same time strengthening the stability of the national power grid through energy arbitrage and rapid response to frequency variations.”
Image courtesy of WEG
