France Connected Its First Solar Panels to the Grid in 1992. Three Decades Later, They Still Have an Astonishing Power Output

  • The solar modules at the Phébus 1 plant in Lyon are still impressively producing 79.5% of their original output.

  • The panels exceed the manufacturers expectations of a 25-year efficiency guarantee of 80%.

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In 1992, when the world still saw solar power as a futuristic promise, France opened the Phébus 1 plant, pioneering its connection to the French electricity grid. Now, over three decades later, its solar panels are still operating at nearly the same efficiency, proving that solar power was as resilient an investment as a fine French wine.

31 years of service. In Lyon, Hespul, a non-profit renewables association, connected a small 1 kW PV array called Phébus 1 to the French grid.

After dismantling the small 108-square-foot solar plant in 2023, technicians subjected the panels to rigorous laboratory tests, obtaining surprising results.

At 80% of their capacity. The solar panels, after 31 years of service, maintain 79.5% of their original output. This not only exceeds the manufacturer’s initial promise of 80% efficiency after 25 years, but also dispels many doubts about the durability of older solar technology.

Rigorous testing. The testing methodology followed industry standards, subjecting the panels to a 1,000 W/m2 flash of light in a dark, temperature-controlled room to measure their maximum instantaneous power output.

The comparison of the values obtained to the original factory measurements revealed an average power loss of 20.5%, indicating a wear of 0.66% per year since 1992. This is an impressive result, especially considering that the degradation rate has been higher over the last 11 years, averaging 1.11% per year.

Not all modules aged equally. Technicians observed two categories within the same batch of modules: One third of them experienced a significant degradation of 33.9% over 31 years, while the rest degraded by 13% over the same period.

These results reflect variations in solar panel materials and manufacturing processes and confirm previous studies, such as the TISO-10 system in Switzerland, which showed differences in module performance due to additives in the encapsulants.

The resilience of solar panels is evident in recent studies. For instance, the National Renewable Energy Laboratory analyzed 1,700 U.S. plants and found an average degradation of about 0.75% per year. Another study in Europe, which evaluated 4,300 residential installations, found an average annual loss of between 0.36% and 0.67%.

The longevity of these solar panels is a testament to the viability of the PV industry as a long-term sustainable energy source. These studies reinforce confidence in long-term investments in solar energy, especially when considering symbolic cases such as Phébus 1, France’s first grid-connected solar array.

Image | Hespul

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