Assessment of Photovoltaic Module Failures in the Field
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Assessment of Photovoltaic Module Failures in the Field Report IEA-PVPS T13-09:2017 Cover figure is from chapter 3.3.3, Fig. 49, where more detail is provided. INTERNATIONAL ENERGY AGENCY PHOTOVOLTAIC POWER SYSTEMS PROGRAMME Assessment of Photovoltaic Module Failures in the Field IEA PVPS Task 13, Subtask 3 Report IEA-PVPS T13-09:2017 May 2017 ISBN 978-3-906042-54-1 Authors: Marc Köntges Institute for Solar Energy Research Hamelin, Emmerthal, Germany Gernot Oreski Polymer Competence Center Leoben GmbH, Leoben, Austria Ulrike Jahn, Magnus Herz TÜV Rheinland Energy GmbH, Cologne, Germany Peter Hacke NREL, Golden, Colorado, USA Karl-Anders Weiss Fraunhofer Institute for Solar Energy Systems ISE, Freiburg, Germany Authors: Guillaume Razongles CEA - INES, Le Bourget du Lac, France Marco Paggi IMT School for Advanced Studies Lucca, Italy David Parlevliet Murdoch University, Australia Tadanori Tanahashi National Institute of Advanced Industrial Science and Technology, Japan Roger H. French Case Western Reserve University, Cleveland, Ohio, USA Contributing authors: Mauricio Richter, Caroline Tjengdrawira 3E, BEL, Belgium Arnaud Morlier Institute for Solar Energy Research Hamelin, Emmerthal, Germany Hengyu LI, Laure-Emmanuelle Perret-Aebi Centre Suisse d'Electronique et Microtechnique SA Karl A. Berger, Austrian Institute of Technology GmbH, Center for Energy, Vienna, Austria George Makrides The University of Cyprus, PV Technology Laboratory, Cyprus Werner Herrmann TÜV Rheinland Energy GmbH, Cologne, Germany Table of Contents Table of Contents ............................................................................................................................... 3 Foreword ............................................................................................................................................ 5 Acknowledgements ............................................................................................................................ 6 List of Abbreviations ........................................................................................................................... 7 Definitions .......................................................................................................................................... 8 Executive Summary ............................................................................................................................ 9 1 Introduction ............................................................................................................................. 11 2 Modelling of Known PV Module Failure .................................................................................. 12 2.1 Description of material based failures ...............................................................................12 2.1.1 Photovoltaic Encapsulants: EVA, Silicones, POE ...................................................... 12 2.1.2 Auto-oxidation of EVA – Role of acetic acid ............................................................. 13 2.1.3 Browning of EVA ....................................................................................................... 14 2.2 PV module failure modes related to material interactions ...............................................16 2.2.1 Influence of encapsulant-backsheet combinations on PV module degradation modes ....................................................................................................................... 17 2.2.2 Lamination process related quality issues ............................................................... 20 2.2.3 Influence of the lamination process on the reliability ............................................. 23 2.2.4 Materials and potential induced degradation ......................................................... 25 2.2.5 Materials and Snail Tracks ........................................................................................ 26 2.2.6 Materials and corrosion of interconnection and silver grid ..................................... 27 2.2.7 Materials and delamination ..................................................................................... 27 2.3 Influence of failures on PV module power ........................................................................28 2.3.1 Influence of EVA browning on PV power ................................................................. 30 2.3.2 Influence of delamination on PV power................................................................... 31 2.3.3 Influence of cell cracking to PV module power ........................................................ 33 2.3.4 Influence of the potential-induced degradation by shunting on the PV power ...... 36 2.3.5 Influence of the silver grid corrosion on the PV power ........................................... 43 2.3.6 Influence of dust soiling on PV power ...................................................................... 49 2.3.7 Influence of biological soiling on PV power ............................................................. 53 3 Database on Module Failure Modes and their Impact on the PV Module Power ................... 57 3.1 Review of other field failure databases .............................................................................57 3.1.1 Expert data acquisition ............................................................................................. 58 3.1.2 Voluntary reporting .................................................................................................. 58 3 3.1.3 Long-term outdoor measurements .......................................................................... 59 3.1.4 General trends from the data that has been published ........................................... 59 3.2 Description of the PV system failure survey ..................................................................... 61 3.2.1 Simple standard roof top system ............................................................................. 64 3.2.2 Large system with components of various types ..................................................... 64 3.2.3 Enter only PV modules of a PV system ..................................................................... 65 3.2.4 Input of special system characteristics..................................................................... 65 3.3 Findings of the PV system failure survey data base.......................................................... 67 3.3.1 Composition of the survey data ............................................................................... 67 3.3.2 Data processing for evaluation ................................................................................. 69 3.3.3 Results ...................................................................................................................... 72 3.4 Description of the visual inspection data collection tool for PV module conditions ........ 78 3.5 Findings of the PV module condition data base ............................................................... 83 3.5.1 Composition of the PV module condition data ........................................................ 83 3.5.2 Data processing for evaluation ................................................................................. 84 3.5.3 Results ...................................................................................................................... 85 4 Local and Operational Stressors for PV Modules ..................................................................... 89 4.1 Implications of data base evaluation on local climatic stressors ...................................... 89 4.2 Climatic stress classification for PV modules with the help of Geographical Information Systems ............................................................................................................................. 90 4.2.1 Categorization of local loads with Köppen-Geiger climate zone or new categorization systems ............................................................................................. 90 4.2.2 Stress factor mapping applied to soiling in MENA region ........................................ 92 4.3 Interpretation of test methods according to local loads .................................................. 93 4.3.1 General requirements of test methods for reliability testing .................................. 93 4.3.2 Potential induced loads ............................................................................................ 94 4.4 Climate and load adapted testing ..................................................................................... 98 Conclusion ........................................................................................................................................ 99 References ...................................................................................................................................... 101 4 Foreword The International Energy Agency (IEA), founded in November 1974, is an autonomous body within the framework of the Organization for Economic Co-operation and Development (OECD) which carries out a comprehensive programme of energy co-operation among its member countries. The European Union also participates in the work of the IEA. Collaboration in research, develop- ment, and demonstration of new technologies has been an important part of the Agency’s Pro- gramme. The IEA Photovoltaic Power Systems Programme (PVPS) is one of the collaborative R&D Agree- ments established within the IEA. Since 1993, the PVPS