Photoluminescence imaging of silicon modules in a string

Abstract

Spectral imaging techniques are a powerful tool for surveillance and monitoring of degradation mechanisms in PV modules. Luminescence images of solar modules have until recently been predominantly acquired in controlled laboratory settings. Recent attempts have been made in detecting luminescence in daylight. This study aims to present a proof of concept for detection of photoluminescence with sunlight excitation. It enables imaging of several modules in a string as well as several strings simultaneously by changing the operating point through wireless and contactless communication with one or more string inverters. This new approach is validated with the electroluminescence technique as well as with an already established photoluminescence technique under sunlight excitation. Due to the string inverter's reaction time, the change in illumination results in lower image quality. However, with a more up-to-date imaging equipment, this approach is promising for identification of certain degradation mechanisms which can be detected with lower resolution such as large area damage and inactive areas. Further studies are needed to optimize the method and potentially use it in connection with an unmanned aerial vehicle inspection.

Accelerated Stress Testing of Perovskite Photovoltaic Modules: Differentiating Degradation Modes with Electroluminescence Imaging

“…For further improvement of MHP mini-modules, using nondestructive methods such as the electro-optical imaging presented here will be essential to differentiate degradation modes and improve specificity of accelerated stress testing procedures, as well as to compare results against outdoor deployment. Indeed, pairing of stress testing and a standard practice for commercial Si PV modules, with many examples across the research community, [52][53][54][55][56][57] advanced test labs, [58] and standardized procedures for image collection and analysis. [59] For commercial PV technologies, imaging has also been implemented outdoors in the field [60][61][62] and tools are available for in-line screening.…”

A review of imaging methods for detection of photoluminescence in field-installed photovoltaic modules

“…Camera detectors used for PL imaging are either silicon (Si) or indium gallium arsenide (InGaAs) detectors. For imaging outdoor, InGaAs cameras are preferred [16][17][18][19][20][21][22][23] because of their high quantum efficiency in the relevant wavelength region [8].…”

“…The reason for that might be that it was tested on aluminum back-surface field (Al-BSF) cell technology. Imaging modules with higher open circuit voltage V OC might give better results [5,23].…”

Large‐Scale Daylight Photoluminescence: Automated Photovoltaic Module Operating Point Detection and Performance Loss Assessment by Quantitative Signal Analysis

“…Koester et al [ 9 ] used devices in the field to switch from MPP at normal operation to OC by turning off the inverter or MPP tracker, or disconnecting the string via combiner box switches. A similar approach is used by Vukovic et al modulating the OP of an inverter remotely, [ 11 ] and further by exploiting the automatic IV sweep in modern inverters. [ 12 ] Images recorded during this IV sweep will include images of both OPs, which are defined and subtracted afterward.…”