Annual expansion in delamination of front encapsulant in tropical climate Field-Operated PV modules

Various kinds of PV module deteriorations are interested in field operation. This work investigated the annual expansion of front encapsulant delamination of PV modules. One string consisting of 16 polycrystalline silicon PV modules connected in series, operated under the tropical climate condition since 2003, was used for monitoring. Starting from the 7th year following the procedure, the electrical parameters at standard test conditions of all modules and the visual inspections were annually measured, and the images were taken by a high-resolution digital camera. At the 16th year, the results indicate that the highest power output achieved by any of the modules was less than 80% of the value on the nameplate. At the 19th year, the module power was 63% of the value on the nameplate at the 75th percentile. Delamination zones were calculated from the high-resolution images of each cell, and the areas were analyzed with perimeters using the ImageJ program and OpenCV module in Python. At the 80th percentile, the delamination area was found to have increased from 8% to 30% in four years. The progressive enlargement of the delamination region in cells placed at the center was more than on cells at the corner of the module. Expansion characteristics of delamination zones were also observed. The expansion rate of delamination was more horizontal than in the vertical direction. Several new delamination zones were found on cells located at more than cells at the corner of the module. The displacement vector of the centroid of the delamination region was proposed to track the direction of annual delamination expansion.