A new study by Diego A. Prieto Melo, Dr. Christin Hoffmann, Prof. Iain Staffell and Prof. Felix Müsgens has been accepted for publication in Energy Economics. The article entitled "From shine to decline: Degradation of over 1 million solar photovoltaic systems in Germany" provides new empirical insights into the long-term performance development of photovoltaic systems under real operating conditions.

The analysis is based on a unique data set of more than one million PV systems in Germany, which are observed over a period of up to 16 years and cover an installed capacity of around 35 GW. This large-scale empirical approach enables a much more robust assessment of degradation patterns than previous studies, which are usually based on smaller samples or shorter observation periods.

The results show that PV annexes have an average annual performance degradation of around 0.59 %. At the same time, the degradation rate decreases over time, which indicates that the power losses slow down with increasing age of the annexes. In addition, the influence of environmental factors becomes clear: extreme temperatures and air pollution have a significant negative impact on power generation.

Overall, the results suggest that frequently assumed degradation rates could overestimate the actual power losses in temperate climate zones such as Germany. This has important implications for investment decisions, energy policy design and the long-term modelling of energy systems.

A summary of the study has also been published in PV Magazine: www.pv-magazine.com/2026/03/18/survey-reveals-pv-systems-in-germany-outperform-lifespan-expectations/

The full article is available here: www.sciencedirect.com/science/article/pii/S0140988326001611