L R AS Published on Saturday 3 February 2024 - n° 474 - Categories:panels

NREL confirms median panel loss of 0.75% p.a.

The US NREL examined the degradation of commercial and utility PV sites in the US between 2008 and 2022. It examined data from 25,000 inverters at nearly 2,500 commercial and utility PV sites, equivalent to 8 GW of solar power. The average age of the PV systems observed was five years.

The researchers highlighted

a median loss of performance of 0.75% per year. This value is similar to that of previous studies. Systems used in warmer climates showed twice as much performance loss as those in colder climates, at 0.88% per year and 0.48% per year respectively. Overall, 90% of the systems studied recorded performance losses of less than 2% per year.

The short-term impact of extreme weather conditions, such as floods, high winds, hail, forest fires and lightning, was minimal in most of the PV systems studied. The median outage time after an extreme weather event was two to four days, resulting in a median loss of 1% annual performance.

In total, 12 out of 6,400 systems experienced outages lasting two weeks or more. Most of the outages were caused by flooding and rain, followed by wind. Most of the systems in the dataset experienced only one weather-related outage.

When weather conditions are powerful enough, they can accelerate long-term degradation. Hailstones larger than 25 mm in diameter, winds of 90 km/h and snow of more than 1 metre resulted in greater annual performance losses in PV systems, such as mechanical stress cracking solar cells.


PV Magazine of 29 January 2024

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