Switzerland’s largest alpine photovoltaic (PV) installation, built on the wall of the Muttsee dam, has begun supplying balancing energy to Swissgrid, the national grid operator. The 2.2 MW facility is part of the PV4Balancing pilot project, designed to test how solar PV systems can help stabilise grid fluctuations typically managed by conventional power plants.
PV4Balancing demonstrates that photovoltaic plants can actively contribute to balancing supply and demand despite the variable nature of solar output due to weather. Swissgrid can request the Muttsee plant to reduce output when there is surplus electricity on the grid. To improve market participation, multiple PV systems are aggregated under the pilot.
Owned by Axpo and IWB, with Denner as the long-term electricity off-taker, the Muttsee installation reflects a strong commitment to aiding the energy transition and increasing the integration of solar into the Swiss grid. The Muttsee dam, completed in 2014 as part of the Limmern pumped storage project, is Europe’s highest reservoir at 2474 metres above sea level and features Switzerland’s longest dam wall. The PV plant construction faced delays due to heavy snow, difficult access, and supply chain issues during the Covid pandemic, but was finally completed in summer 2022.
PV4Balancing is pioneering a new ancillary services approach, allowing PV plants to contribute tertiary balancing energy by temporarily reducing output within 12.5 minutes of activation. The pilot runs through June 2026, with plans to integrate this service into Switzerland’s regular balancing market by 2027.
