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Wet leakage resistance development of modules with various backsheet types
Author(s) -
Buerhop Claudia,
Stroyuk Oleksandr,
Zöcklein Julian,
Pickel Tobias,
Hauch Jens,
Peters Ian Marius
Publication year - 2022
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3481
Subject(s) - leakage (economics) , inverter , materials science , photovoltaic system , coating , electrical impedance , humidity , composite material , environmental science , optoelectronics , electrical engineering , power (physics) , meteorology , physics , thermodynamics , engineering , economics , macroeconomics
Over the last years, a significant number of inverter shutdowns most likely due to degraded backsheets have been reported by operators, investors, and manufacturers. We investigated water ingress into different backsheets, and the resulting risk for inverter shutdowns. For studying pending insulation issues of inverters, we analyzed exemplarily a 5‐MWp photovoltaic (PV) power station with 20,530 PV modules and 314 inverters. For backsheet identification on‐site near‐infrared absorption spectroscopic measurements of 518 PV modules from 20 inverters were carried out. In the lab, wet leakage tests provide kinetic data of insulation resistances for different backsheet materials. Historic ground impedance data logged by the inverter were evaluated to show the temporal evolution of inverters with different backsheets. We observe different kinetics and drops in leakage resistance for different backsheet types based on polyamide (PA) and air‐side fluorinated coating (FC), and distinguish between two types of behavior. “PA‐like” is characterized by moderate leakage resistance loss and slower performance reduction with regard to insulation in the field. “FC‐like” is characterized by high susceptibility to water and a high leakage resistance loss rate for PV modules after 6–8 years of operation. These characteristics are indicated when measuring inverter GI in dependence of temperature and humidity. For PA‐based BSs, the reduction in ground impedance (GI) is steady over 8 years. We observe incidences with GI below the critical value of 400 kΩ on 2.8% of all days. For FC‐based BSs, we also observe steady decrease of average GI initially, yet after 6 years in the field, we see a sudden and rapid decline for 20% of those inverters. GI falling below the critical value is observed on up to 5% of all days, with the trend increasing. Therefore we, expect this problem to become even more severe for longer operating times.