Matthias Ebert

Matthias Ebert
Fraunhofer Center for Silicon Photovoltaics · Reliability of Solar Modules and Systems

PhD

About

101
Publications
26,560
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
890
Citations
Introduction
Matthias Ebert currently works at the Reliability of Solar Modules and Systems, Fraunhofer Center for Silicon Photovoltaics.
Additional affiliations
September 2007 - present
Fraunhofer Center for Silicon Photovoltaics
Position
  • Head of group
Description
  • Materials, Components and Module Characterization Thermo-Mechanical Finite Element Simulations CFD Simulation Accelerated Life Time Cycling Outdoor module efficiency and energy yield Characterization of Electrolysis Systems and Components
March 2003 - August 2007
Fraunhofer Institute for Microstructure of Materials and Systems IMWS
Position
  • Researcher
October 1996 - February 2003
Bauhaus University Weimar
Position
  • Researcher

Publications

Publications (101)
Conference Paper
A reduction of series resistance loss due to a declined current in halved cell modules (compared to full cell modules) is applied by several PV module manufacturers. In [1] the outdoor performance of a grid connected array, which used the half-size cell design, was examined. The advantages of half-size cells in PV modules in comparison to full-size...
Preprint
In order to harmonize supply and demand of green energy, new future-proof technologies are needed. Here, hydrogen plays a key role. It is considered to be sustainable and contributes to achieving climate change goals if it is produced using renewable electricity. Within the current framework conditions, the production of green hydrogen is not yet e...
Conference Paper
It is well known that thin film modules like CdTe have certain power meta instabilities depending on their short-and long-term history. For CdTe extensive dark storage (e.g. due to transportation or modules from warehouse) typically lead to a lower output power and requires extensive light stabilization prior indoor STC characterization. IEC 61215-...
Conference Paper
Solar integration in the building envelope still represents a niche market, despite legal requirements and regulation, e.g. nearly zero-energy buildings (NZEB), which, in addition to a high overall energy efficiency, requires alternative energy generation in or near the building. A recent study entitles that building facades offering a so far untap...
Article
The global share of photovoltaic plants in desert locations increases continuously due to inexpensive land and higher yield due to higher irradiation levels. However, PV modules suffer from harsh environmental conditions that influence their lifetime and, consequently, the levelized cost of electricity. Environmental factors such as high temperatur...
Conference Paper
The module certification according to standard IEC 61215-series mainly provides for one-factor stresses to accelerate aging of PV modules. In principle, the test legs have proven themselves to exclude significant faulty designs over the past decades. However, there are a growing number of cases where this has not been successful as for those field...
Conference Paper
Performing peel tests on the backsheets of PV modules is a common procedure for quality control of laminates. The tests are often used to evaluate delivery batches, but also to test modules in the field. In order to make interpretations of the aging state, it is necessary to evaluate and understand the change in peel strength over time (ac-celerate...
Conference Paper
The current worldwide market share of bifacial solar modules is around 10% in 2020 and is expected to increase to at least to 35% in 2030 [1]. Fundamental cell and module designs for bifacial PV exist but there is still a strong need for the development of dedicated module designs that are optimized in improved energy yield and of LCOE. To shape th...
Presentation
Please visit the main paper here: https://www.sciencedirect.com/science/article/pii/S0306261920314689?via%3Dihub The global share installations of photovoltaic (PV) power plants in desert locations increases continuously due to the inexpensive land and higher yield. In these areas, PV power production benefits from high irradiation levels, but PV...
Conference Paper
Monitoring data of photovoltaic (PV) systems offer a great opportunity for the application of machine learning approaches. Currently, among these approaches, artificial neural networks have become very popular. In this paper, the application of such models will be further investigated and recommendations for data quality and training processes for...
Conference Paper
Wasserstoff besitzt ein großes Potential, ein wichtiger „Baustein bei der Abkehr von fossilen Brennstoffen in der Industrie und Mobilität zu werden“ [1]. Er kann in die bestehende Erdgasinfrastruktur integriert werden und so den Kohlenstoffausstoß von Erdgas als Energie für Heizung, Verkehr und Industrie reduzieren. Darüber hinaus kann er als kohle...
Conference Paper
Der Anteil erneuerbarer Energiequellen am deutschen Strommarkt wächst stetig, stellt die Netzbetreiber jedoch vor Herausforderungen. Photovoltaik- und Windenergieanlagen stellen Strom nur fluktuierend zur Verfügung, sodass es zu Überangeboten oder Engpässen auf dem Strommarkt kommt. [1] Die größte Herausforderung stellt hierbei die ökonomisch sinnv...
Conference Paper
The part of renewable energy sources in the German electricity market is growing steadily, but confronts grid operators with challenges. Photovoltaic and wind energy plants only provide electricity at fluctuating times, resulting in oversupply or congestion on the electricity market. [1] The greatest challenge here is the economically sensible stor...
Conference Paper
Full-text available
Photovoltaic Module product development is still very much based on cost pressure, experience, empirical rules, partly on design of experiments and therefore extensive testing compared to e.g. the automotive or wind power industry. Many aspects are evaluated by testing physical prototypes and with classic trial & error further understanding of the...
Conference Paper
Full-text available
Light-induced degradation (LID) is a known crystalline silicon cell effect that becomes noticeable in the first hours of light soaking or in the first days to weeks of operation of the PV system. The potential power loss is normally less than 3 % identified in the type approval test according to IEC 61215-2:2016 during stabilization (MQT 19.1), typ...
Conference Paper
Full-text available
Lichtinduzierte Degradation (LID) ist ein bekannter Zelleffekt, der sich in den ersten Stunden im Lightsoaking (≈1000W/m2) oder in den ersten Monaten des Betriebs einer PV-Anlage bemerkbar macht. Alle c-Si-Modultypen sind betroffen. Typischerweise wird eine Leitungsdegradation von 3 % im ersten Betriebsjahr auf den Datenblättern angeben (Jahr-1 Deg...
Conference Paper
Full-text available
Anlagenbesitzer und O&M (Operation & Maintenance) Anbieter profitieren von einem einwandfreien Betrieb ihrer PV-Systeme. Unplanmäßige oder zu viele Wartungseingriffe aufgrund von Defekten oder Verschattun-gen führen zu hohen Ertragsverlusten und Betriebskosten, die sich nachteilig auf die Profitabilität des PV Systems auswirken. Auf Basis von Metho...
Conference Paper
Full-text available
Das vor über 10 Jahren erstmal beobachtete Phänomen der Potenzialinduzierte Degradation (PID) entsteht bei PV-Strings, in denen die Zellen gegenüber den geerdeten Modulrahmen eine hohe Spannungsdifferenz aufzeigen [1.][2.]. Diese Spannungsdifferenz veranlasst positiv geladene Metallionen, sich durch die Passivierungsschicht der Zellen hindurch zu b...
Presentation
Full-text available
The finite element simulation has become an important and powerful tool for optimizing and securing the quality and reliability of PV modules. Design variants can be evaluated in a shorter time and new concepts can be evaluated. The presentation presents specific results that have been incorporated into the development of module prototypes in the F...
Conference Paper
Full-text available
Light Induced Degradation (LID) is a well-known cell effect, impacting in the first hours of testing or first months of operation. All c-Si device types are affected, typically with less than 5% degradation. The known mechanisms (Boron Oxygen complex formation and Iron Boron pair dissociation) are identified during certification by IEC 61215:2016 s...
Presentation
Full-text available
LID is a well known effect, impacting in the first hours of testing or first months of operation. Testing at higher temperatures of PERC devices resulted in much higher degradation levels, but slower degradation rates than BO, termed Light Induced Degradation at Elevated Temperatures (LeTID). The presentation gives an overview of known LID mechanis...
Conference Paper
Full-text available
The progressive substitution of conventional energy generation from fossil fuels by renewable energy sources is creating new challenges for the intelligent management of electricity. At times of high supply, it is important to remove excess electricity from the grid, store it and supply it back to the grid at short-term intervals if necessary. Du...
Presentation
Dust deposition on PV modules leads to significant losses in energy yield, but its prediction is still a challenging problem in PV modelling. In this presentation, a method for the characterization of soiling losses on basis of module measurements is explained and establishes a correlation to the responsible evironmental conditions.
Presentation
Full-text available
Characterization of performance- and soiling-behavior of bifacial solar modules in desert environment.
Conference Paper
Dust deposition on the surface of PV modules (soiling) leads to significant losses in energy yield particularly in desert climates, where high daily yield losses due to soiling can be observed. However, its estimation is still an open challenge in PV modeling. The intensity of soiling losses strongly depends on its environmental conditions. The aim...
Conference Paper
Fatigue of solar cell interconnectors is a serious failure mode for solar modules, as their interruption can lead to severe loss in module power as well as safety issues (e.g. arcing). Currently early failure and design issues are investigated by time consuming thermal cycling tests. Cyclic mechanical load testing accelerates this failure mode. Wit...
Presentation
Full-text available
Photovoltaic Modules are designed for lifetimes of 20-25 years in moderate climatic environments. However, the impact of desert loads on PV modules can affect the lifetime and performance of PV modules. In this presentation, we have shown different desert loads and possible solutions to overcome these challenges.
Conference Paper
Fatigue of solar cell interconnectors is one of the key failure modes for PV modules. Interconnectors are loaded when cell displacement takes place due to temperature changes and mechanical loading of the PV module. Currently, time consuming thermal cycling tests are used to identify early failure and design issues of PV modules related to ribbon f...
Conference Paper
Modules with bifacial technology show a high gain compared to monofacial modules, due to utilization of an illuminated rear side, as reported in different publications [1, 2]. The utilization of both sides leads to new opportunities for outside applications, such as open field or building integrated (BIPV) installations. Regarding this fact, bifaci...
Research
Full-text available
Research Group „Reliability of Solar Modules and Systems“- R&D Competencies
Article
Research Group „Reliability of Solar Modules and Systems“- R&D Competencies
Article
To test reproducibility of a technical specification under development for potential-induced degradation (PID) and polarization, three crystalline silicon module types were distributed in five replicas each to five laboratories. Stress tests were performed in environmental chambers at 60 °C, 85% relative humidity, 96 h, and with module nameplate sy...
Conference Paper
Full-text available
Electrical conductive adhesives are a promising alternative to common soldering technologies. Advantages are lower process temperatures (<150°C), meaning lower mechanical stresses, relatively simple process technology with opportunity for automation and environment-friendliness, since there is no lead and flux necessary. This paper focuses on the m...
Conference Paper
Full-text available
Cracks in encapsulated solar cells are a common defect in photovoltaic modules and they are currently strongly investigated, since they can lead to efficiency losses and lifetime reduction of the modules. In order to investigate the development of cracks in encapsulated solar cells under mechanical loads, a novel experimental setup was developed th...
Article
Full-text available
Abstract This case study deals with the assessment of different metallization layouts on the reliability of encapsulated solar cells. Six different metallization layouts were modelled by means of finite- element- modelling. In a first step cooling after soldering was simulated and the mechanical stress field in the silicon determined. In a second s...
Conference Paper
Full-text available
Fatigue of solar cell interconnectors is a key failure mode for PV modules. Loading of interconnectors occurs when cell displacement takes place due to temperature changes and mechanical loading of PV modules. The aim of this paper is the application of a numerical lifetime estimation concept for solar cell interconnectors. The stress-strain consti...
Conference Paper
Under field conditions solar modules are subjected to simultaneous loads, among other things, mechanical and thermal loads. Both of them can be affected by local air flow around the solar modules. Regarding the distribution of temperature through the module, solar cells in principle can be considered as heat source. This is due to the difference be...
Conference Paper
Full-text available
Cracks in crystalline solar cells in photovoltaic modules can be caused by applied mechanical loads. They can lead to efficiency losses and lifetime reduction of the modules. In order to investigate the development of cracks in encapsulated solar cells, a novel experimental setup was developed that applies loads under well-known boundary conditions...
Conference Paper
Within this contribution several 3D Finite- element- models have been created in order to simulate processing of solar cells (lamination, soldering) as well as mechanical bending. The stress state for each load case was analysed with respect to magnitude and direction of principal stresses. For the process steps there are di erent mechanisms that i...
Conference Paper
Solar Modules are subjected to wind loads, leading to a non-uniform pressure distribution across the module. By means of CFD simulations the pressure profile was calculated. The pressure was transferred to a mechanical simulation calculating the stresses in the glass and solar cells. Applying a reliability concept for brittle materials the probabil...
Conference Paper
Full-text available
In recent studies strength tests on several batches of glass were carried out by ring on ring test. Glass from several manufacturers as well as production dates was included into these investigations. The Weibull distribution function was used to evaluate the stresses. Results show that the characteristic strength values can differ significantly fr...
Article
In recent studies the mechanical reliability of encapsulated solar cells was numerically investigated. A finite element model of a solar module with all essential components, such as cells, polymer layers and frame was created. The principle stress field in each solar cell was calculated by exposing the module to distributed pressure loads on the g...
Conference Paper
Full-text available
Cracks in crystalline solar cells in photovoltaic modules can be caused by applied mechanical stresses. To investigate the development of cracks in encapsulated solar cells a new approach was chosen that analyzes thermal and mechanical loading systematically. For this purpose two experiments are established using mini-module specimens with three or...
Article
Mechanical and thermal loads on photovoltaic modules (PV modules) lead to mechanical stresses in the module parts and especially in the encapsulated solar cells which can break under a certain load. To investigate the development of cracks in encapsulated solar cells, a novel approach was developed that systematically analyzes the influence of the...
Conference Paper
Full-text available
Within current studies the assessment of the mechanical reliability of solar modules on basis of probabilistic material strength data for glass was introduced. Ring on ring strength tests according to ISO 1288-5 were carried out for several float glass manufacturers. Weibull parameters were evaluated on basis of strength test results. The results s...
Article
Soldering of solar cell strings is a critical step in the production of photovoltaic modules. During the soldering process significant mechanical stresses are induced in the stringed cell assembly. Since silicon has a much smaller coefficient of thermal expansion than copper it is compressed by the copper-ribbon during the cooling phase. The result...
Article
In recent investigations using various analysis methods it has been shown that mechanical or thermal loading of PV modules leads to mechanical stress in the module parts and especially in the encapsulated solar cells. Cracks in crystalline solar cells are a characteristic defect that is caused by mechanical stress. They can lead to efficiency losse...
Conference Paper
Full-text available
Since decades, Ethylene-vinylacetate (EVA) materials are used for embedding crystalline and thin film solar cells. Because of their interesting processing properties, thermoplastic materials such as Polyvinyl-butyral (PVB) or Thermoplastic Silicon Elastomers (TPSE) come more and more into focus. One of their disadvantages can be an increased materi...
Conference Paper
Full-text available
This paper is proposed to enhance the mechanical simulation model for crystalline solar modules by implementing the viscoelastic behaviour of the encapsulation material ethylene-vinyl acetate (EVA). The material is characterized by thermo-mechanical analysis (TMA) experiments. Utilizing time-temperature superposition techniques a master-curve is co...
Article
Full-text available
The majority of solar module manufacturers use ethylene-vinyl acetate (EVA) copolymer foils as the encapsulant material for solar cells and thin-film modules. Because EVA needs long processing times for curing, thermoplastic process materials that do not employ chemical cross-linking have been coming more and more into focus in the encapsulation se...
Conference Paper
This contribution compares different characterization methods and their suitability to detect mechanical and electrical defects. Commercially available photovoltaic (PV) modules were tested using different analysis methods. Some methods are already standard in solar cell inspection like electroluminescence or thermography but have rarely been expan...
Conference Paper
Full-text available
Solar cells mostly are embedded into a soft polymer matrix using vacuum lamination process. Since the early 80´s Ethylenevinylacetate (EVA) is widely used for this purpose. The material is of thermoplastic nature, but cross links covalentely under high temperatures to a non-melt able elastomer. In this work, a method for mathematically describing i...
Article
Photovoltaic modules (PV modules) are supposed to have a lifetime of more than 20 years under various environmental conditions like temperature changes, mechanical loads, etc. Common outdoor exposure may influence efficiency and lifetime which necessitates assessment of PV module performance and detection of output deficits. For this purpose reliab...
Article
Full-text available
Within the following work mechanical and thermo-mechanical studies on embedded solar cells were carried out. Temperature dependant material properties such as shear modulus and coefficient of thermal expansion of an EVA encapsulant were determined by dynamic mechanical analysis (DMA) and thermo mechanical analysis (TMA). Those parameters were integ...
Conference Paper
The lifetime and reliability of photovoltaic modules (PV modules) is influenced by defects which have their origin either in manufacturing processes or in operation exposure. Characterization of PV modules is necessary for manufacturers to assure their warranty and to observe process difficulties during production process and for improving their mo...
Article
A novel micromachined thermal emitter for fast transient temperature operation is presented. Compared to most commercial available thermal emitters, the one here presented is able to operate in a pulsed mode. This allows the use of lock-in techniques or pyrodetectors in the data acquisition without the use of an optical chopper for light modulation...
Article
Full-text available
A micromachined thermal emitter for fast transient temperature operation with a novel hot-plate concept is presented. This concept is based on a nonaxis-symmetric design with excellent mechanical properties during temperature modulation combined with high thermal decoupling. Especially, the mechanical stress induced by the thermal expansion of the...
Conference Paper
Full-text available
Within recent research special mechanical challenges on solar modules and cells were investigated. Recordings on photovoltaic installations showed that around 68 % of mechanical failed modules were due to dimensioning problems. Those dimensioning problems can occur from insufficient module design as well as the mounting and substructure design. Fur...
Conference Paper
This contribution describes the analysis of mechanical properties of photovoltaic modules by analyzing the responding vibration of the module after mechanical excitation. For this purpose a measuring system was established using a commercially available laser scanning vibrometer. Investigations were done on PV modules and on laminated glass-polymer...
Conference Paper
Full-text available
Glass/polymer/glass laminates have been manufactured in a vacuum lamination process. A laminate stack of front glass, encapsulate polymer (Ethylenevinylacetate - EVA) and a back glass was combined under constant load, vacuum and varying temperature profile. In this work, a procedure and experimental results to examine the influence of process contr...
Conference Paper
The numerical pre-design of a novel micro-machined thermal infrared emitter, using a spider type hotplate concept is presented. The spider concept introduced allows the fast transient operation of the emitter and thus a direct modulation of the radiation without additional mechanical tools like choppers. The thermal radiation source is excited by a...
Conference Paper
In this paper investigations for the non-destructive characterization of MEMS (Micro-Electro-Mechanical- Systems) are presented that can be applied in the produ