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28 Years of Operational Data for a Utility Scale 103 kWp PV Plant (1989-2017) Analysis of Degradation of PV Modules, Inverters and System Performance with Technical and Economical Comparison to the Repowered 260 kWp PV Plant (2017-2019)
T. Nordmann, T. Vontobel
Degradation, Reliability, System Performance, Long-Term Field Data
PV Systems and Storage – Modelling, Design, Operation and Performance
Subtopic: Operation, Performance and Maintenance of PV Systems
Event: 37th European Photovoltaic Solar Energy Conference and Exhibition
Session: 5DO.5.3
1405 - 1408
ISBN: 3-936338-73-6
Paper DOI: 10.4229/EUPVSEC20202020-5DO.5.3
0,00 EUR
Document(s): paper, presentation


The PV plant on the noise barrier of the highway A13 at the time of its construction 1989 was the largest PV plant in Switzerland (104 kWp) and the first PV noise barrier plant worldwide, providing 28 years of field data for analysis. Degradation of PV modules, inverter efficiency and system performance are analyzed. A technological and economical comparison with the 260 kWp PV plant after repowering 2017 is performed. Flasher measurements at STC of the 1989 PV modules after 28 years of operation show degradation of nominal power from 15…37%, corresponding to 0.55…1.32% per year. Inverter efficiency after 12 years of operation is 1.12% lower at 91.61%. Yield decrease started 2007, but was partially compensated by increasing solar irradiation. Analysis of performance ratio shows a linear decrease from 2006 to 2016. Performance decrease is far higher than can be explained with PV module and inverter efficiency degradation. It is therefore to large parts due to degradation in Balance of System (BoS) components such as array boxes, DC wiring, fuses, et. al. The repowered PV plant produces almost 3 times the energy of the original PV plant on the same length of noise barrier while system prices have dropped 95.1% from 1989 to 2017.