Photovoltaic benchmark plant on Mont-Soleil

A photovoltaic benchmark plant is to be installed on Mont-Soleil using PV modules made by different manufacturers from various parts of the world to carry out scientific analysis of their energy output and quality and to compare them.


  • Lead school(s) School of Engineering and Computer Science
  • Institute Institute for Energy and Mobility Research
    IEM / Photovoltaic systems
  • Duration (planned) 01.01.2023 - 31.12.2025
  • Project management Prof. Dr. Christof Bucher
  • Head of project Matthias Burri
  • Project staff Sina Julia Spring
  • Partner Société Mont-Soleil
    Espace Découverte Energie
  • Keywords Photovoltaics, PV, solar energy, Mont-Soleil, PV modules


Since 1988, internationally recognised research, development and demonstration work in the field of photovoltaics has been carried out on 1270-metre-high Mont-Soleil in the Bernese Jura. These activities focus on efficiency, lifespan, storage and the integration of power from regenerative energy sources into the grid.

The Mont-Soleil solar power plant is one of very few large-scale photovoltaic systems over 30 years old. Its degradation – at 0.13 percent per year – has been low thus far. This means it has far exceeded all expectations in terms of lifespan and energy output. Despite some minor defects and visual signs of ageing on the PV modules, there is nothing to indicate the plant will need to be urgently decommissioned any time soon. But at the same time, it clearly cannot continue to operate forever either, which is why the Société Mont-Soleil has been weighing up various future scenarios for the past few years. An evaluation of the PV market carried out in 2020/21 shows there is a global lack of neutral, scientifically verified and publicly accessible product comparison information that evaluates the quality, performance and lifespan of relevant modules fairly based on objective criteria.

As part of a pilot project, a concept is now being tested where the most relevant PV modules from Switzerland, Europe and worldwide will in future be periodically operated, scientifically analysed and compared on a benchmark plant – the only one of its kind in the world. Defective PV modules on the 30-year-old plant will be gradually replaced by new ones, doubling the facility’s efficiency and energy output. The data will be made publicly accessible to encourage researchers all over the world to use it to carry out further analysis and evaluation.


By the end of May 2023, the pilot project aims to install five different types of module from three different parts of the world (Switzerland/EU, USA, Asia) and incorporating four different technologies (PERC, IBC, HJT, TOPcon) – with a total of 40 modules and output of around 15 kW – and to connect them to measurement technology so that the data can be recorded and evaluated.

The long-term goal is to gradually replace the now inefficient PV modules on Mont-Soleil with much more high-performance and globally relevant new ones over the coming years and decades. The researchers can then test them using internationally recognised methods and compare them in the long run with the long-term data of the Mont-Soleil plant, which has been recorded since 1992.

This would also significantly increase the output of the Mont-Soleil plant and provide attractive innovation impetus on the market, for developers and for industrial and government funding of top-quality, high-performance and long-life PV modules. It would also raise Mont-Soleil’s profile internationally, attracting visitors from Switzerland and abroad. The project hopes to set internationally recognised PV standards in terms of quality and transparency.

The pilot plant is being constructed in collaboration with the PV lab at Scuola Universitaria Professionale della Svizzera (SUPSI) as well as the PV lab at the Swiss Federal Institute of Technology Lausanne in Neuchâtel. Before installation, all PV modules will undergo in-depth inspection at SUPSI, where their output, temperature and low-light performance and cell breakage will be analysed. 

Looking ahead

The facility will be used to test measurement and IT systems and to create a scientific community based around the benchmark system. Various stakeholders will participate in the project, whose interests and involvement are to be defined.

The benchmark plant pursues a clear vision: it aspires to becoming one of the largest and best-known PV plants in the world, for which the most relevant PV modules on the market will be purchased anonymously each year for an unspecific period of time, and the initial and operating measurement data will be made publicly available. It is hoped this will increase quality awareness in Switzerland, but also worldwide, and make a contribution towards the longevity of photovoltaics, which has been the Mont-Soleil PV plant’s vision for three decades.