Christina Hirschl

SAL Silicon Austria Labs · Sensor Systems

PV modules made of crystalline silicon solar cells suffer an initial slight loss in peak power, an effect known as "light induced power stabilization". Many module producers know this effect and have this light induced degradation (LID) included in their product guarantee. Before starting the IEC reliability tests, PV modules need to show a stable...

Photovoltaic (PV) plants typically suffer from a significant degradation in performance over time due to multiple factors. Operation and maintenance systems aim at increasing the efficiency and profitability of PV plants by analyzing the monitoring data and by applying data-driven methods for assessing the causes of such performance degradation. Tw...

Copper sinter paste has been recently established as a robust die-attach material for high -power electronic packaging. This paper proposes and studies the implementation of copper sinter paste materials to create top-side interconnects, which can substitute wire bonds in power packages. Here, copper sinter paste was exploited as a fully printed in...

Bifacial solar panels installed on flat rooftop of industrial buildings are an effective way to boost the yield. The albedo of the flat roof determines to great extent the bifacial gain. However, because it changes due to soiling and moss growth, the power output of bifacial PV installations over time is difficult to calculate. For the purpose of e...

Various types of next-generation encapsulation films based on polyolefins have recently been introduced and could attract market attention. These material innovations can be classified as polyolefin elastomer (POE) and thermoplastic polyolefin (TPO) encapsulants, both of which consist of a polyethylene backbone with different side groups. The main...

With the growing significance of printed sensors on the electronics market, new demands on quality and reproducibility have arisen. While most printing processes on standard substrates (e.g., Polyethylene terephthalate (PET)) are well-defined, the printing on substrates with rather porous, fibrous and rough surfaces (e.g., uncoated paper) contains...

Anomaly detection is becoming increasingly important to enhance reliability and resiliency in the Industry 4.0 framework. In this work, we investigate different methods for anomaly detection on in-production manufacturing machines taking into account their variability, both in operation and in wear conditions. We demonstrate how the nature of the a...

The weathering stability of polymeric backsheets is very important for the reliability of photovoltaic (PV) modules. In addition to reliability, cost reduction and sustainability are upcoming challenges the PV backsheet industry is facing with. The most commonly used material for PV backsheets is poly(ethylene‐terephthalate)‐PET. However, PET is in...

Within the last years, an increased occurrence of backsheet cracking, especially of Polyamide-based backsheets, was observed in PV installations and reported in literature. Thus, a detailed failure analysis on cracked polymeric backsheets was performed in order to identify the drivers leading to the unexpected behaviour of the Polyamide multilayer...

Looking at the distribution of reported PV-module defects, backsheet failures such as discolourations, delamination and cracking is one of the most common error groups. Especially within the last years, an enhanced occurrence of Polyamide backsheet cracking was observed in PV installations and reported. Thus, a detailed failure analysis on cracked...

The goal of this work was to implement a wireless RFID-based Sensor Network in the UHF frequency region inside a semiconductor cleaning machine to supplement existing sensors in order to simplify usability and reduce production costs. The sensors are chosen in a way to extract useful information about the status of the semiconductor production mach...

Resistive temperature sensors on two different commercially available uncoated paper substrates have been manufactured using inkjet printing of silver nanoparticles. Their dedication is to be integrated in lightweight materials made from natural fibre-reinforced biopolymers for condition monitoring during the manufacturing process and beyond. The p...

The research project INFINITY focuses on design improvements for PV system components operating in different climatic regions. This topic gained pertinence in recent years due to increased installation rates worldwide with the highest growth rates in non-moderate climates. As PV components are not optimized to the respective climate zone, the targe...

During their outdoor service, photovoltaic (PV) modules are exposed to different set of external stresses that can affect their efficiency and lifetime such as UV irradiation, temperature and humidity cycles, rain, snow and wind loads, hail, sand and/or salt. Moreover, internal stresses such as choice of materials and design (additives, morphology...

An inkjet- and 3D-printed capacitive sensor system with an all-digital and flexible sensor read-out hardware is reported. It enables spectrometer devices with significantly reduced device outlines and costs. The sensor is developed as multilayer inkjet-printed electrode structure on a 3D-printed copper housing. Very high required position resolutio...

During their outdoor service, photovoltaic (PV) modules are exposed to different set of external stresses that can affect their efficiency and lifetime such as UV irradiation, temperature and humidity cycles, rain, snow and wind loads, hail, sand and/or salt. Moreover, internal stresses such as choice of materials and design (additives, morphology...

As the PV market shows enormous potential with huge growth rates especially in climatic-sensible regions, specific artificial ageing test procedures are a key point for an efficient and fast product development of new PV modules/materials optimized for the use in specific climatic regions. Based on the definition of 4 climate profiles (dry and hot...

Over the last years, the development of innovative, fast and non-destructive characterisation techniques for the detection of PV-module failures and advanced analysis of yield losses in photovoltaic power plants has become a key challenge in scientific research. Besides standard on-site thermographic screening, several novel and easily applied meth...

The very strict purity requirements of polymer parts that are used in the semiconductor manufacturing industry lead to an excessively low yield rate. To decrease the costs in the production chain, detailed knowledge about possible impurities during each processing step is essential. This work provides an overview of non-destructive testing techniqu...

Microclimatic conditions inside of the enclosures of photovoltaic (PV) inverters are suspected to have a tremendous impact on degradation and failure modes of the devices. To address this issue, a custom multi-channel data logger has been designed which is capable of continuously measuring temperature, relative humidity and wetness in confined spac...

Several series of six-cell photovoltaic test-modules-intact and with deliberately generated failures (micro-cracks, cell cracks, glass breakage and connection defects)-were artificially and naturally aged. They were exposed to various stress conditions (temperature, humidity and irradiation) in different climate chambers in order to identify (i) th...

ABSTRACT Photovoltaic modules can experience damages of varying severity in the case of heavy hail storms. In the worst case, complete glass and solar cell breakage results in efficiency and security losses of the affected modules which therefore have to be replaced. However, there is a strong need to inspect the remaining modules directly in the f...

This work reports on the prospects of using luminescence spectroscopy as a non-destructive method for the characterization of ethylene vinyl acetate copolymer (EVA) crosslinking in photovoltaic (PV) modules. Luminescence has the potential to be easily applied in-line for monitoring purposes, e.g. during manufacturing. We investigate the correlation...

A misfit strain or stress in a thin layer on the surface of a wafer lets the composite disk warp. When the wafer is thin and large, the Stoney estimation of the film stress as function of the curvature yields large errors. We present a nonlinear analytical model that describes the relationship between warpage and film stress on an anisotropic wafer, a...

Ethylene vinyl acetate (EVA) is the dominating material for the encapsulation of solar cells. A better understanding of the cross-linking reaction progress during PV module lamination could lead to promising approaches for shortening of PV module lamination times but also for optimization of the EVA formulation. Therefore, the main aim of this stud...

In photovoltaics, the quality of the polymeric solar cell embedding material is of key importance for the long-term durability and performance of the PV modules. For the most common encapsulant, elasto¬meric ethylene vinyl acetate (EVA), the degree of crosslinking is a key issue in this respect. Raman spectroscopy was researched as a fully contact-...

The feasibility of simulating thin-film-on-substrates behaviour of large thin coated wafers using Ansys® “layered shells” is estimated. Layered shell elements are based on Mindlin-plates with coupled intrinsic layers. These elements can be used with an update Lagrange algorithm (NLGEOM). They are of interest because they are easy to use and require...

The optical loss due to the busbar grid and soldered interconnector ribbons on a three busbar standard multicrystalline silicon solar cell’s front side is at 2.3%. One way to reduce this optical loss on cell level and in a photovoltaic (PV) module is to use deep structured ribbons as cell connectors. The standard soldered, flat ribbon is replaced w...

Since the beginning of PV module production, Soxhlet extraction has been the standard method for the determination of the gel content and the resulting calculation of the degree of crosslinking of the most common PV encapsulant ethylene vinyl acetate (EVA). While the method is deemed well established and several pertinent ASTM and ISO standards exi...

Raman spectrometry was applied to an urgent problem in industrial process control of renewable energy system manufacturing. A ratiometric approach evaluating the relative CH2/CH3 intensities proved a reliable measurand for determining the degree of crosslinking of ethylene/vinyl acetate non-destructively in-situ inside assembled PV modules. After e...

Polymers are used in different applications with strict demands regarding their performance over long periods of time. Therefore, the mechanical, electrical and optical properties have to be controlled during the fabrication. As cross-linking is a crucial process step it is necessary to establish reliable technologies to monitor the degree of cross...

With a strong industrial trend towards using thin silicon in semiconductor devices, process legacy-induced stresses are matter of increasing practical importance. A key problem here is a lack of suitable metrology equipment for measuring inherent substrate material stresses in the manufacturing line. To overcome this, the use of Raman microspectrom...

Two different THz applications in the semiconductor industry were explored and validated against established reference measurement techniques and simulations. The first application investigated the possibility of measuring mechanical deformation behaviour of silicon wafers. Time-domain THz tomography mapping scans were carried out to measure wafer...

A common challenge in modern multi-physics simulations like FEM is that the more complex the underlying problems become, the more the simulation depends on a range of not or just poorly understood parameters. At the same time, the increase of FEM computing time with the complexity of the underlying problem makes it impossible to explore the whole p...

The deformation of large thin uncoated silicon wafers without remaining intrinsic misfit stresses resting on a ring is investigated. We use both, Finite Element simulations and THz tomography mapping. Specific attention is given the scaling of the warping for increasing slenderness of those wafers. We follow the approach of starting with a known so...

Title: Post-Crosslinking in Photovoltaic Modules under Different Conditions Abstract/Summary: The serious pricing pressure in the manufacturing of photovoltaic (PV) modules causes an immediate need for a reduction of production costs. The time limiting process in PV manufacturing lines is the lamination process. Today, the predominately used emb...

Over the last years potential induced degradation (PID) occurred on several photovoltaic (PV) power plants and therefore increased interest in researching this phenomenon. It is known that PID occurs when certain material combinations coincide with a high negative potential between the solar cells and frame of the module. Furthermore the degradatio...

Usually, stresses in module integrated solar cells are obtained by Finite Element (FE) calculations because these stresses can hardly be determined by measurements. Apart from the knowledge of the material properties, the FE boundary conditions have a distinct effect on the results of a FE solution for a standard mechanical pressure test. We u...

Snail tracks are discolorations of the silver fingers on solar cells. We present a measurement system that can detect snail tracks. Their origin is unknown, but they are thought to be linked to micro cracks in the solar cell. Regions with micro cracks on a photovoltaic module were identified using electroluminescence measurements. Based on the elec...

Vibrational spectroscopy was found to be a suitable method for the determination of the degree of cross-linking of ethylene vinyl acetate (EVA) polymers. Spectral changes in the Raman spectra of EVA with increasing lamination time (which equals increasing degree of cross-linking) were mainly detected in the CH vibrational regions, namely, in the re...

In recent years the potential induced degradation (PID) of photovoltaic modules (crystalline and thin film) has attracted a strong interest, as it turned out that PID occurs frequently in PV systems and solar parks. PID is the loss of system power initiated by leakage currents at high voltages. The phenomenon occurs most commonly in photovoltaic (P...

With the increasing use of PV installations and the highly competitive situation on the PV module market, the modules’ reliability and long-term performance over projected operational lifetimes of 25+ years become key factors. One component known to have a vital impact on the long-term characteristics, and hence of particular interest here, is the...

With the increasing use of PV installations and the highly competitive situation on the PV module market, the modules’ reliability and long-term performance over projected operational lifetimes of 25+ years become key factors. One component known to have a vital impact on the long-term characteristics, and hence of particular interest here, is the...

A total of 16 analytical methods, spanning from classical solvent extraction over different thermo-analytic and mechanical approaches to acoustic and optical spectroscopy, have been evaluated as to their ability to determine the crosslinking state of ethylene vinyl acetate (EVA), the prevailing encapsulant for photovoltaics applications. The key ob...

A key factor for the long-term performance degradation of PV modules is an in-use damage of the actual solar cells by loads causing (micro-)cracks. Besides external mechanical forces, the main source of these is forces created by different thermal expansions of the module components, inducing mechanical loads as soon as the module temperature chang...

The Shore hardness parameter is proposed as an analogue for the degree of cross-linking in ethylene vinyl acetate (EVA) sheets. The parameter is measured for a series of EVA sheets, both individually and as part of a mini-module. The gel content, which is another analogue of cross-linking, is measured using the Soxhlet test and correlated with the...

A new kind of calorimeter has been developed at Austrian Aerospace to measure specific material parameters needed for the analysis of thermal vacuum insulation. A detailed description of the measuring device and the measurement results will be given in this paper. This calorimeter facility allows to measure the heat flow through the insulation unde...

For hard-particle systems the perturbations associated with specific Lyapunov exponents exhibit spatial structures to which we refer as Lyapunov modes. The perturbations generating the smallest-positive exponents are delocalized and have a wave-like appearance reminiscent of the modes of fluctuating hydrodynamics. The degeneracy of the associated e...

We consider simulations of a two-dimensional gas of hard disks in a rectangular container and study the Lyapunov spectrum near the vanishing Lyapunov exponents. To this spectrum are associated “eigen-directions”, called Lyapunov modes. We carefully analyze these modes and show how they are naturally associated with vector fields over the container....