On-Site Identification of the Material Composition of PV Modules with Mobile Spectroscopic Devices

Abstract

With the increased development of portable and handheld molecular spectrometers within recent years, new fields of applications have opened up, such as their use (i) for material identification of samples contained in large and non-portable components and (ii) the detection of material degradation effects and failures directly in the plant. The usability and transferability of well-established analytical characterization techniques, such as attenuated total reflection (ATR) Infrared (IR)-, Raman, and Near-Infrared (NIR)-spectroscopy as mobile devices for the in-field characterization of Photovoltaic (PV) modules, are described and discussed. Material identification of the polymeric compounds incorporated in the PV modules (encapsulants, backsheets) is often an important task, especially when degradation and failures occur. Whereas the knowledge of the bill of materials is one challenge, the detection of material degradation effects is another important issue. Both tasks can be solved nondestructively by the application of mobile spectrometers. Raman spectroscopy is the best-suited method for the identification of the encapsulant within the module (measurement through 3-mm glass), while NIR measurements allowed for the nondestructive determination of the composition of the multilayer backsheet. Surface degradation effects (e.g., oxidation, hydrolysis) are best detectable with IR-spectroscopy. The application of mobile devices allows for direct material analysis in the field without dismantling PV modules, transporting them to the lab, cutting them in smaller pieces, and analyzing them in conventional bench-top spectrometers.

On the Use of Oxidation Induction Time as a Kinetic Parameter for Condition Monitoring and Lifetime Evaluation under Ionizing Radiation Environments

“…Some of these methods do not require specific sampling (e.g., determination of the indentation module, medium, and near infrared spectroscopies). In contrast, other methods require microsamples (e.g., determination of the modulus of elasticity profile, IR spectroscopy for laboratory testing, thermogravimetry analysis, density measurements, gel fraction determination, and solvent absorption) [14][15][16][17][18][19]. Many evaluations are based on the measurement of physicochemical properties (such as infrared spectra, melting/crystallization temperature [20], glass transition temperature or mechanical tests [21], mass loss during laboratory aging [22], or electrical tests) rather than on oxidation induction time (OIT) tests.…”

Distinguishing between different types of multi‐layered PET‐based backsheets of PV modules with near‐infrared spectroscopy

“…Spectroscopic methods, such as Fourier‐transform infrared (FTIR), Raman and fluorescence spectroscopy, were found to be most suitable to address this challenge due to their high chemical specificity and non‐destructive character 1,7,10–14 . However, these techniques are capable of probing only the BS surface layer and cannot provide information on the inner structure of multi‐layer BSs that are typically several hundred μm thick.…”

“…However, these techniques are capable of probing only the BS surface layer and cannot provide information on the inner structure of multi‐layer BSs that are typically several hundred μm thick. By this reason, the investigations into structure and degradation state of multi‐layer BSs using Raman, FTIR and fluorescence spectroscopy typically have an invasive character and need to be performed on BS cross‐sections 7,13–17 . In‐depth non‐invasive probing by confocal Raman spectroscopy is feasible for new PV modules but typically hindered for field‐aged samples due to a strong fluorescence from partially degraded encapsulant and BS materials 14 …”

“…Recently, near‐infrared absorption (NIRA) spectroscopy has been recognized as a viable alternative to other spectroscopic approaches 14,18 that can be upgraded from lab tests to large‐scale field measurements and implemented as a non‐destructive and non‐invasive high‐throughput characterization tool for large PV systems. NIRA can provide a combination of penetration depth (more than a thousand μm), versatility of analytic information, and field applicability unrivaled by other spectroscopic approaches proposed for the characterization of PV modules so far.…”

Advanced analysis of backsheet failures from 26 power plants

“…Another approach is to identify the polymers present in the layer structure with spectroscopic methods. To this end, Eder et al have shown the possibility to identify the layer stacks on-site with spectroscopic methods (Raman and NIR) [6]. However, on-site analysis of the material is typically limited to known layer stacks, that can be classified and might be not suitable to identify.…”