Why Do PV Modules Fail?

PV modules that are sold on the worldwide market today have to pass the relevant IEC tests for certification. These tests are only a mark for a certain quality level, not a reliability test. Nevertheless, manufacturers of PV modules give performance guaranties of 20 to 25 years on their products, some even more. Therefore the question to be asked is: 'How to survive 25+ years between the pole and the equator?' or, seen from the other side: 'Why do PV modules fail?' To answer this important question we will show a global approach, starting with the presentation of general failure reasons. On the one hand, extrinsic PV module failures can be caused by different climatic stress factors and by defective installations. In the following, we will show a classification of those factors, which provides the basis for weathering analyses in the lab. With this data background some major failures and related test methods will be presented. On the other hand, intrinsic failure reasons are to be taken into account. We will exemplify some intrinsic failure reasons on material level. Also, an overview of major failures and their frequency detected during certification will be presented in order to arrive at an assumption as to why modules fail. Finally we will explain adequate test methods to detect and measure the relevant failure factors and to test new materials, components and modules for future photovoltaic systems. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the organizing committee of International Conference on Materials for Advanced Technologies.