The solar installation built on the Muttsee dam wall, Switzerland’s largest alpine PV plant, will supply balancing energy to the national grid operator, Swissgrid, from August 2025. The 2.2MW facility is part of the PV4Balancing pilot project, which is testing how photovoltaic systems can support grid stability.
PV4Balancing is designed to show that solar power can contribute to balancing fluctuations in supply and demand, a service usually provided by conventional plants. Because solar output depends on weather conditions, forecasting is difficult. Under the pilot, Swissgrid can request the Muttsee plant to reduce output when there is surplus electricity in the grid. Multiple PV systems are aggregated to improve participation in balancing services.
AlpinSolar is owned by Axpo and IWB, with Denner as the long-term electricity off-taker. The companies said the project demonstrates their commitment to supporting the energy transition and working with Swissgrid to further integrate solar power into the Swiss energy system.
The Muttsee dam, completed in 2014 as part of the Limmern pumped storage project, is Europe’s highest reservoir at 2474m above sea level and the longest dam wall in Switzerland. The site was considered for solar even before construction finished, with the south-facing wall providing a suitable slope for panels. Construction of the PV plant was delayed by heavy snow, difficult access and supply chain disruptions during the pandemic, with work finally completed in summer 2022.
