Evaluation of PV module field performance

Abstract

This paper describes an effort to inspect and evaluate PV modules in order to determine what failure or degradation modes are occurring in field installations. This paper will report on the results of six site visits, including the Sacramento Municipal Utility District (SMUD) Hedge Array, Tu cson Electric Power (TEP) Springerville, Central Florida Utility, Florida Solar Energy Center (FSEC), the TEP Solar Test Yard, and University of To ledo installations. The effort here makes use of a recently developed field inspection data collection protocol, and the results were input into a corresponding database. The results of this work have also been used to develop a draft of the IEC standard for climate and application specific accelerated stress testing beyond module qualification.

Mechanisms of adhesion degradation at the photovoltiac module's cell metallization‐encapsulant interface

“…It is most commonly observed to selectively occur around the interconnect ribbons and cell metallization . For instance, there are numerous examples in the literature of Arco Solar and Siemens Solar modules exhibiting delamination of the encapsulant from the cell near the bus bar and on the grid finger metallization, Figure . A correlated observation has recently been made during a study of encapsulant to Si‐cell adhesion, while the delamination of pristine samples showed no interface preference in the cohesive zone ahead of the delamination front, samples that had been aged at 85°C/13.5% relative humidity (RH) clearly demonstrated preferential delamination at the gridlines, Figure .…”

Delamination-and Electromigration-Related Failures in Solar Panels—A Review

“…Remarkably, the encapsulant delamination is considered to be one of the main degradations that affect the PV modules' overall performance. As discussed previously, various forms of encapsulant delamination were identified in the field, including front glass-encapsulant delamination, cells, interconnecting ribbons, and back sheet [57,58]. Conversely, they mostly share some of the effects, causes, and mechanisms, and they differ in impacting PV modules.…”

Degradation in photovoltaic encapsulation strength of attachment: Results of the first PVQAT TG5 artificial weathering study

“…Systematic quantitative studies of encapsulant adhesion are historically lacking in the PV literature. In their absence, qualitative examinations provide anecdotal support for insights including: 1) the encapsulation/cell interface is typically weaker than the encapsulation/glass interface [3], [5], [6], with observations of delamination being reported at both interfaces in veteran installations [3]; 2) the use of a primer, enabled with an adequate degree of cure in poly(ethylene-co-vinyl acetate) (EVA) encapsulant, facilitates good adhesion [1], [2], [7]; and 3) delamination often precedes corrosion in fielded PV modules [1], [8]. The observation of delamination at locations with disparate climates [3] suggests that delamination may be aided by the complex history of conditions present through the life of a module.…”

“…It was theorized at the time that the coupling agent would form an interpenetrating network, i.e., an intermediate layer covalently bonded to the glass and the bulk encapsulant [1]. Since then, delamination has been observed in veteran PV installations in a wide variety of locations and climates [3]. The topic of adhesion has historically been addressed using analogous strength-of-attachment methods, with just recent advances in the direct quantification of interfacial adhesion and cohesive failure using fracture-mechanics approaches.…”