Regular Article

Analysis of the degradation of amorphous silicon mini-modules under a severe sequential UV/DH test

¹ Univ Paris-Est Créteil, CERTES, IUT de Sénart-Fontainebleau, 36 rue Georges Charpak, 77127 Lieusaint, France
² ICAM, site de Grand-Paris Sud, Carré Sénart, 34 Points de Vue, 77127 Lieusaint, France
³ SLITE-Source, 3 rue Léon Blum, 91120 Palaiseau, France
⁴ SOLEMS, 3 rue Léon Blum, 91120 Palaiseau, France

*e-mail: julia.vincent@icam.fr

Received: 27 January 2023
Received in final form: 9 May 2023
Accepted: 5 June 2023
Published online: 24 August 2023

Abstract

This study presents the results of severe accelerated tests carried out on four encapsulated amorphous silicon (a-Si) mini-modules. All the a-Si mini-modules were exposed to a 85 °C and 85% relative humidity damp heat (DH) prolonged treatment for 5000 h representing five times the duration specified by the IEC 61215 standard for qualification tests. For two of the four mini-modules, the DH test was preceded by a severe UV preconditioning, by applying 30 times the dose of 15 kWh/m² at a temperature of 50 °C as prescribed by the IEC 61215 standard, in order to enhance the degradation during the following DH test and to reduce the overall testing time. I–V curves were plotted with a time step of 100 h under standard test conditions (STC) using a class A solar simulator and a source meter in order to monitor the degradation throughout both the tests. A visual inspection with photographic capturing was also performed at each stage to detect the apparent defects. Corrosion observed after 2000 h owing to the ingress of humidity is explained here by two possible infiltration paths in the layers of the mini-modules. Delamination occurred after 5000 h for the PV mini-modules which underwent the extended DH test. After 5000 h of damp heat testing, the degradation of the maximal power (P_max) was found to be slightly accelerated for the a-Si mini-modules that were previously exposed to a severe UV preconditioning, with a value reaching 80% of its initial value, whereas, for the others only subjected to the prolonged DH test, the maximal power remained above 80% of its initial value. In all cases, the mini-modules seemed highly reliable with no failure after 5000 h of accelerated testing, and, based on an equivalent time of 20 years for 1000 h of accelerated test, they would exhibit a limited degradation rate of 0.2%/year in outdoor field conditions.