Alpiq has advanced plans for a large-scale battery energy storage system in the canton of Solothurn, securing a pre-connection agreement with Swiss transmission grid operator Swissgrid for 300 megawatts of grid connection capacity at the Niedergösgen site.

Project Scale and Location

The planned battery energy storage system, located next to Alpiq's Gösgen run-of-river power plant in Niedergösgen, will carry a power capacity of 300 MW and a storage capacity exceeding 1.2 gigawatt-hours, placing it among the largest battery storage facilities in Switzerland.

The site sits in proximity to both the Gösgen nuclear power plant and the Gösgen hydroelectric power plant and connects directly to the Swiss transmission grid at what Alpiq describes as a central grid node.

According to Alpiq, the facility will be capable of supplying around 500,000 households with electricity for more than four hours. The company said the location's proximity to existing energy infrastructure and its access to a major grid hub were decisive factors in the project's development.

Milestone Reached with Swissgrid Agreement

The signing of the pre-connection agreement with Swissgrid represents what Alpiq has described as a major milestone for the project. The agreement secures the 300 MW grid connection capacity to the national transmission grid, a prerequisite for a project of this scale moving into formal planning and construction phases.

Amédée Murisier, Head of the Assets business unit and a member of Alpiq's Executive Board, said the Niedergösgen site combines the key requirements for a large-scale battery project, citing proximity to existing energy infrastructure and connection to an important grid hub.

"This BESS project represents another milestone for Alpiq in the consistent implementation of our ambitious growth strategy," Murisier said. "We are making targeted investments in flexibility and contributing directly to the security of supply and the integration of renewable energies into the energy system."

Timeline Toward 2029 Commissioning

Alpiq said it is now moving the project forward at full speed following the pre-connection agreement. Initial discussions with representatives of the relevant authorities have already taken place, and the company said dialogue with the local community is a priority.

A planning application is expected to be submitted following those exchanges. Construction is scheduled to begin in 2027, with commissioning planned for 2029.

Role in Grid Stability and the Energy Transition

Alpiq framed the Niedergösgen project as a direct response to the growing need for flexible energy infrastructure as renewable generation expands across Europe. Battery energy storage systems and pumped-storage hydropower, the company said, are key tools for integrating weather-dependent output from solar and wind installations into the grid, balancing short-term fluctuations, and strengthening security of supply.

The 300 MW facility is intended to relieve load on the Swiss transmission grid and support the country's transition to a low-carbon energy system by storing and dispatching electricity in response to grid conditions.

Alpiq's Broader Storage Portfolio

The Niedergösgen project sits within a broader expansion of Alpiq's flexible generation and storage assets across Europe. The company holds stakes in several pumped-storage hydropower facilities in Switzerland, including Grande Dixence, Nant de Drance, and FMHL. It is also pursuing a pumped-storage power plant project in Spain.

In the battery storage segment specifically, Alpiq said it has secured a portfolio exceeding 1 gigawatt across multiple European markets. Approximately one-third of that capacity is already in operation at 130 MW or under construction at 230 MW.

The company said its overall operational battery storage portfolio is set to grow to several gigawatts in the coming years, with the Niedergösgen project forming a significant component of that expansion. The media release was issued from Lausanne on June 30, 2026.

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