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 car- ries 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, development, and demonstration of new technologies has been an important part of the Agency’s Programme.
The IEA Photovoltaic Power Systems Programme (PVPS) is one of the collaborative R&D Agree- ments established within the IEA. Since 1993, the PVPS participants have been conducting a variety of joint projects in the application of photovoltaic conversion of solar energy into electricity.
The mission of the IEA PVPS Technology Collaboration Programme is: To enhance the international collaborative efforts which facilitate the role of photovoltaic solar energy as a cornerstone in the transition to sustainable energy systems. The underlying assumption is that the market for PV sys- tems is rapidly expanding to significant penetrations in grid-connected markets in an increasing number of countries, connected to both the distribution network and the central transmission net- work.
This strong market expansion requires the availability of and access to reliable information on the performance and sustainability of PV systems, technical and design guidelines, planning methods, financing, etc., to be shared with the various actors. In particular, the high penetration of PV into main grids requires the development of new grid and PV inverter management strategies, greater focus on solar forecasting and storage, as well as investigations of the economic and technological impact on the whole energy system. New PV business models need to be developed, as the decen- tralised character of photovoltaics shifts the responsibility for energy generation more into the hands of private owners, municipalities, cities, and regions.
IEA PVPS Task 13 engages in focusing the international collaboration in improving the reliability of photovoltaic systems and subsystems by collecting, analysing and disseminating information on their technical performance and failures, providing a basis for their technical assessment, and de- veloping practical recommendations for improving their electrical and economic output.
The current members of the IEA PVPS Task 13 include:
Australia, Austria, Belgium, China, Denmark, Finland, France, Germany, Israel, Italy, Japan, Malay- sia, Netherlands, Norway, SolarPower Europe, Spain, Sweden, Switzerland, Thailand, and the United States of America.
This report concentrates on the reliability of PV modules. The reliability of PV modules is described by theoretical models. We focus on available models and not in any case on the most important degradation mechanisms. Furthermore, statistical data of the PV module reliability in the field is presented and analysed. The importance of local environmental stressors, such as temperature, humidity, irradiance, wind, etc., influencing the reliability test methods is discussed.
The editors of the document are Marc Köntges, Institute for Solar Energy Research Hamelin, Em- merthal, Germany (DEU), Gernot Oreski, Polymer Competence Center, Leoben, Austria (AUT), and Ulrike Jahn, TÜV Rheinland Energy, Germany.
The report expresses, as much as possible, the international consensus of opinion of the Task 13 experts on the subject dealt with. Further information on the activities and results of the Task can be found at: http://www.iea-pvps.org.
Currently plenty of PV module failures are known. For investors these failures are difficult to assess because there is little information how much impact and how often a specific failure mode occurs in real world PV systems. The lack of information adds an unnecessary uncertainty to the risk of investment. In this document we try to analyse this problem from three perspectives.
The first perspective is the view of a scientist, PV module expert or manufacturer. In chapter 2 we summarize PV module failure models. These models allow one to analyse the impact of specific well-known degradation modes and failures on the module power with a dependence on weather conditions. These models allow a manufacturer or a PV module expert to evaluate the power loss risk for specific known failures for a specific product. This information can be used to define the warranty criteria for the product. However, most of the failures have not been evaluated to this depth in literature. For these failures, data is summarized from the literature to explain the root cause mechanisms and, if possible, ways to simulate their impact on power production in the fu- ture. A framework is explained to model the power loss of multiple failures.
The second perspective is the view of an investor, banker or underwriter. We collect PV system failure data for four climate zones. These data allow analysing the occurrence of a failure relative to other failure types and its impact on the system power.
Finally, the third perspective is the view of a test institute and PV system planner. Here we explain how one has to modify testing methods for specific failure types to special regions. This allows adapting test methods for a given PV module to specific regional requirements.