Tests show 30 year-old solar panels still operating at 79.5 per cent of original capacity

A rooftop solar system installed more than 30 years ago in France – reported to be the country’s oldest installed system – is still operating at just under 80 per cent of its original output, a new report has found.

The 1kW system, first inaugurated June 1992 in Ain in eastern France, was tested by Hespul, an agency formed in 1991 to support the development of renewable energy technologies in France – and which commissioned the 1992 solar array.

Hespul says it dismantled the 31 year-old PV system and tested the panels in a laboratory under current international standards.

This included placing the panels in a dark room at a controlled temperature and flashing them with a light with a power of 1000W/m2, at which point their maximum instantaneous power was measured. This value was then compared to that measured at the time of their original manufacturing 31 years ago.

The test found that the modules produce on average 79.5 per cent of their original power output, despite being in operation for 31 years.

The same test, carried out on the 20^th anniversary of the panels’ installation, found they were producing at 91.7 per cent of their original power.

In a statement, Hespul says the tests demonstrate the reliability of photovoltaics, as a mature technology with “the capacity to become one of the major sources of energy in France and in the world.”

“These results are also consistent with the manufacturers’ performance commitments, which generally guarantee panel production of more than 80% after 25 years of operation,” Hespul added.

The tests were carried out through a corporate sponsorship by French certification body Certisolis, who carried out the testing, and French solar specialist Isowatt, who dismantled and reassembled the solar panels.