Research project

Achilles – Advanced Characterization of Photovoltaics for Hail Resistance

Fortunately, the number of PV systems on Swiss roofs is constantly increasing. However, climate change is also expected to increase the number of hail events and thus hail damage. When glass breaks, a module must always be replaced. However, it is often not easy to determine whether the module is so badly damaged that replacement is necessary.

With the mobile PV laboratory of SPF (www.pv-lab.ch), cell damage can be reliably detected and classified. In this way, over 500 PV systems were measured in Switzerland after the severe hail events in 2021. In the Achilles project, this data is being evaluated and the influences of various parameters such as hailstone size or the year of construction of the systems on the development of module and cell damage are being analysed.

Furthermore, the long-term behaviour of cell damage is to be investigated. Shortly after cell cracks have formed, they have little influence on the performance or safety of the modules, but this can change in the medium to long term. A module with minor damage can often continue to supply energy for a long time without any problems and therefore does not need to be replaced immediately. However, it is important to have a reliable basis for deciding when a module needs to be replaced. Therefore, a test procedure for accelerated ageing of PV modules with regard to the long-term effect of hail damage is to be developed and tested on different modules with and without hail damage. Finally, recommendations will be drawn up for the procedure to be followed after a hailstorm and for the assessment of hail damage.

The aim of the project is to gain a better understanding of how microcracks form in different types of modules, and of their ageing and long-term behaviour in terms of safety and energy yield. The result will be a guideline for experts on how to assess hail damage to PV modules.