Are solar panels still usable after 31? Scientists have tested some of the oldest panels in the laboratory

Tests reveal important findings for the energy transition. Not all solar panels are equally robust, but a trend is discernible.

What kind of modules are we talking about? As our colleagues at Xataka report, the Hespul charity installed a series of small 1kW modules in Lyon in 1992 and connected them to the grid – a first. They were the first solar modules in France. Their name: Phébus 1. In 2023, the solar panels were dismantled and taken to the laboratory. Are they still usable after 31 years of operation in all weathers?

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Beyond the guarantee

What did the tests reveal? On average, the mini power plant achieved an efficiency of 80 percent. Some modules deteriorated by around 34 percent and others lost as little as 13 percent of their output. The manufacturers guaranteed much less: they only promised 80 percent efficiency across all modules after 25 years. The modules from Phébus 1 could therefore still be used today without any problems.

What is the difference between the panels? The variance can be explained by the smallest differences in materials and manufacturing – especially in view of the age of the products themselves. The solar industry was still in its infancy at the time, but today we can expect smaller differences and probably a higher level of performance retention. You can read more about this at Gruenes Haus, for example, with references to the Fraunhofer Institute.

How is a solar panel tested? In a completely darkened room, the solar panel is exposed to a bright, standardized flash of light. The amount of electrical energy the panel generates from this is then measured. If this is done at different times – for example 31 years apart – it is possible to see to what extent the panel’s performance has decreased.

So around 80 percent of the incoming solar radiation is converted into electricity? No, the laboratory’s data does not say anything about efficiency. It measures the energy converted into usable electricity. And this value is likely to be poor for these old solar cells from France compared to today, probably less than 20 percent.

As a newsletter from the Federal Ministry for Economic Affairs and Climate Protection states, this figure is now more than 25 percent for top models.

High-tech and clever ideas are also the subject of another article in ours. However, this applicant’s plan has proven to be far less sustainable than solar cells: What a candidate for a university career tried during a state exam in Turkey will probably stay with him for the rest of his life: His attempt to cheat with a camera, cell phone and AI failed, but the police were certainly impressed.

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