The efficiency of photovoltaic installations over time: a sustainable technology

By / 
This article originate from my contributions to Energiris, a Belgian citizens’ cooperative committed to accelerating the energy transition. As part of our mission to inform and raise awareness among both co-owners and the general public, we regularly publish educational content on topics related to sustainable energy.
The original article was published in French and Dutch, reflecting the multilingual context of our cooperative. By sharing them here in English, I also wish to reflect my personal commitment to a more sustainable and better-informed society.

Originally published on the Energiris website – 9 February 2025

Photovoltaic panels have become an essential solution for producing clean, renewable energy. But how do these installations manage to function efficiently after several decades? This article discusses the efficiency of photovoltaic installations over time and the factors that contribute to their longevity.

The efficiency of solar panels over time

Solar panels experience a gradual decline in efficiency over the years. This degradation, generally around 0.5% to 1% per year, is due to environmental factors such as exposure to sunlight, temperature fluctuations and humidity. However, modern panels are designed to minimise this degradation and maintain stable performance.

After 25 years, a solar panel can still produce around 80% of its initial power. This longevity is due to technological advances and rigorous maintenance practices. Monocrystalline panels, for example, offer a longer lifespan thanks to their stable structure.

Factors influencing the lifespan of solar panels

Several factors influence the lifespan of solar panels. Manufacturing quality, installation conditions and maintenance practices play a crucial role. A well-oriented installation that is protected from the elements, as well as regular maintenance, can extend the lifespan of the panels.

Solar panel technologies also vary in terms of durability. Monocrystalline silicon panels, for example, have an average annual degradation rate of 0.3% to 0.5%, while thin-film panels may have a higher degradation rate.

Recent advances in the efficiency and reliability of photovoltaic panels

Recent technological advances have significantly improved the efficiency and reliability of photovoltaic panels. Notable innovations include perovskite cells, which offer higher efficiency than traditional silicon cells. These cells are also lighter and more flexible, allowing them to be integrated into buildings and vehicles.

Anti-reflective coatings and optimised transparent solar panels are other advances that maximise energy production even in low-light conditions. Bifacial solar panels and hybrid models make greater use of solar energy to achieve maximum efficiency.

Case studies of photovoltaic installations still functioning after 20 years

  1. Installation in Freiburg, Germany: This installation, commissioned in 1991, is still fully functional after more than 30 years. Thanks to regular maintenance and technological upgrades, the solar panels continue to produce energy efficiently.
  2. Installation in Sarnia, Canada: This installation, installed in 1981, was renovated in 2011 and continues to operate efficiently. The solar panels have been replaced with more modern models, but the original infrastructure is still in use.
  3. Installation in Lhuis, France: The first photovoltaic installation connected to the French electricity grid, in 1992, totalling just 1 kWp, by the Hespul association. Thirty-one years after their installation, they have been tested and are still capable of producing 79.5% of their initial power. This result exceeds the manufacturer’s guarantee of 80% after 25 years.

Conclusion

Photovoltaic installations are a mature and reliable technology, capable of producing clean energy over long periods of time. Thanks to technological advances and rigorous maintenance practices, these installations can operate efficiently for several decades, contributing to sustainability and energy transition.

Beyond my role at Energiris, I place great importance on sharing knowledge. I have always considered education to be an essential tool for helping everyone better understand energy issues and the concrete solutions available to us. Sharing what I discover and making complex topics accessible to others is also my way of contributing to a fairer, more inclusive transition.

Bibliography, if you would like to learn more about this topic:

Scroll to Top