Germany, panels

The deterioration of PV systems over 15 years old

Published on Monday 22 May 2023 | Article n°446

Researchers have examined the degradation of Suntech solar panels on two roofs installed in 2003, one of 37.8 kW and the other of 18.5 kW, located in the town of Sinsheim (south-west Germany).

They observed :

  • A drop in energy productivity ranging from 1.9% to 2.9% over a 16-year period.
  • The largest system experienced inverter failures in 2009 and 2010.
  • The 18.48 kW system had a higher unit energy productivity than the 37.8 kW installation, particularly in 2009 and 2014-2015.
  • The annual degradation factor for the 37.8 kW system was 0.11%/year, while for the 18.48 kW system it was 0.20%/year. These values are significantly lower than those reported in the existing literature.
  • The actual energy production per available irradiation was 0.817 for the 18.48 kW system and 0.826 for the 37.8 kW system.
  • The measured specific efficiency divided by the theoretical efficiency for the first two years of operation was 96.8% and 95.8%, respectively.
  • The power degradation rate reached 1.9% in the largest system and 2.9% in the smallest system over the 16-year period.

PV Magazine of 16 May 2023

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