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WEG delivered a battery energy storage system in April 2026 for the Callio solar park, located on the site of an old mine in the city of Pyhäjärvi, Finland. The project is one of the first hybrid systems in the Nordic country that combines photovoltaic generation with battery storage. The system includes two battery containers with 8,360 kWh of capacity, a 4,400 kVA power converter, a 4,500 kVA transformer, and integrated control, According to NSC. The delivery was made to Solarigo Systems Oy, investor and operator of the park.
WEG, a multinational from Jaraguá do Sul, has just placed Brazilian technology inside an old mine in Finland, and the result is one of the Santa Catarina company’s most emblematic projects abroad: a battery energy storage system that transforms the site of a deactivated mine into a renewable energy hub. The Callio solar park, in Pyhäjärvi, began operating with photovoltaic generation in June 2025 and now receives the capacity to store the energy produced for use at strategic moments.
The project is one of the first hybrid systems in Finland to combine solar and battery in the same operation. The delivery was made in April 2026 to Solarigo Systems Oy, investor and operator of the park, and WEG‘s system solves a problem that every intermittent renewable source faces: the sun does not shine 24 hours a day, especially in a Nordic country where winter has less than six hours of natural light. Storing the energy generated during the day and releasing it when the grid needs it most is what makes solar generation viable even at extreme latitudes.
What WEG delivered and how the system works
The system supplied by WEG includes two battery containers totaling 8,360 kWh of capacity, a 4,400 kVA power converter, a 4,500 kVA medium and low voltage oil-filled transformer, and a control system that integrates the entire operation. In practice, the batteries absorb the energy generated by the solar panels during the day and release it to the grid when there is demand, functioning as a reservoir that smooths out oscillations between generation and consumption.
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The Callio solar park has a capacity of 13 MWp (megawatts-peak), and the 8,360 kWh storage allows a significant portion of this generation to be shifted to peak hours, when electricity is more expensive and the grid is under more pressure. WEG describes the system as designed for energy arbitrage and rapid response to frequency variations, two essential functions for the stability of the Finnish electricity grid, which operates in conjunction with the Nordic electricity market (Nord Pool).
From zinc mine to energy innovation hub
The Pyhäsalmi mine, where the Callio solar park was installed, operated for decades as one of Finland‘s most productive zinc and copper mines. With the depletion of reserves, the site is being redeveloped to host businesses focused on research, development, and sustainable energy solutions, a transformation that Solarigo Systems and WEG made concrete with the combination of solar panels and batteries.
The concept of converting deactivated mines into renewable energy hubs is gaining traction in Europe, where hundreds of abandoned mining sites offer ample land, pre-existing electrical infrastructure, and connection to the transmission grid. Finland, which aims to achieve carbon neutrality by 2035, has regulatory incentives for projects like Callio, and the presence of a Brazilian company supplying the storage system reinforces WEG‘s position as a global competitor in energy technology.
What this means for WEG in the global market
For WEG, the project in Finland is more than a contract: it’s a demonstration of capability in a demanding market. Nordic countries operate one of the world’s most advanced electricity grids, with high penetration of renewables (wind, hydro, and solar) and rigorous requirements for supply quality. Delivering a hybrid system that combines storage, conversion, and integrated control in this environment positions WEG as a reference supplier for similar projects across Europe.
Manfred Peter Johann, Vice President of Automation and Systems at WEG, stated that the system “contributes to transforming a historic mine into an innovation hub for renewable generation and storage, while also reinforcing the stability of the national electricity grid.” The Santa Catarina-based company already supplies equipment to over 130 countries, but the Callio project is especially relevant because it demonstrates mastery over the complete chain of a hybrid solar + battery system, a segment that is growing exponentially worldwide.
Energy storage as a key piece of the energy transition
Battery storage is considered by the International Energy Agency (IEA) as one of the most critical technologies for enabling the global energy transition. Without batteries, solar and wind energy are limited to instantaneous production: when the sun sets or the wind stops, generation drops to zero and the grid needs to activate thermal power plants (gas, coal, or diesel) to compensate, nullifying part of the environmental benefit.
The WEG system in Pyhäjärvi addresses exactly this bottleneck. By storing 8,360 kWh of solar energy generated during the day, the Callio park can dispatch clean electricity even when the panels are not producing, reducing the need for fossil backup and contributing to Finland’s carbon neutrality goal. For Brazil, where large-scale battery storage is still incipient, the project serves as a showcase of what WEG can offer the domestic market when regulation and battery costs make similar projects viable.
Did you know that WEG from Jaraguá do Sul is transforming a deactivated mine in Finland into a renewable energy hub with 100% Brazilian technology? Tell us in the comments what you think of WEG’s presence in Europe and if Brazil should invest more in battery energy storage.
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