Axpo Begins High-Alpine Solar Build to Power Swiss Rail Network

• Axpo starts NalpSolar, an 8 MW alpine PV project in Tujetsch, set to supply Swiss Federal Railways for 20 years under Bern’s Solar Express programme.

Axpo Holding AG has broken ground on NalpSolar, an 8-megawatt photovoltaic plant perched 1,900 metres above sea level in the canton of Graubünden. The alpine facility—Axpo’s first at this altitude—sits on a south-facing plateau near the Lai da Nalps reservoir in Tujetsch, an area famed for deep-winter sunshine even when lowland arrays struggle. Once fully commissioned, the pilot site should deliver roughly 11 gigawatt-hours of electricity a year, enough to serve some 2,000 Swiss households.

Unlike many green-field solar projects, NalpSolar’s output is already spoken for. Axpo has signed a 20-year power-purchase agreement with Swiss Federal Railways (SBB), which will feed the clean power directly into its traction grid. Rail demand peaks during the colder months, making alpine generation valuable because snow reflection and thin, cool air can noticeably boost panel efficiency when the plains are shrouded in fog.

The schedule is deliberately paced to gather data on building in harsh conditions. Axpo aims to connect at least 10 percent of plant capacity by December 2025, then incrementally expand arrays over three construction seasons. Full output is expected by 2028, giving engineers three winters’ worth of performance readings before final build-out. Lessons learned could inform a new wave of high-altitude projects across the Alps.

NalpSolar slots neatly into Bern’s Solar Express programme, an incentive package fast-tracking alpine PV to shore up Switzerland’s winter electricity gap. Parliament approved the measure in 2023 after hydropower shortages and volatile gas prices exposed the limits of the country’s traditional energy mix. To qualify, developers must bring at least 10 percent of capacity online within two years and guarantee substantial cold-season production—criteria Axpo says its site comfortably meets.

For Axpo, Europe’s energy crunch has underscored the importance of diversified renewables. “High-elevation solar won’t replace valley plants, but it can stabilise supply when it’s needed most,” said André Burkhard, head of solar at the Zurich-based utility. “If NalpSolar performs as our models predict, we’ll replicate the concept at other reservoirs.”

Swiss authorities hope such replication comes quickly. The Energy Strategy 2050 calls for tripling domestic solar output by mid-century, with at least 2 terawatt-hours originating from the mountains. NalpSolar’s progress will be an early test of whether the peaks can deliver on that ambition.