The market for Photovoltaic systems has experienced an enormous growth worldwide and will further grow over the coming decades. Investments in Photovoltaics became an important financial product with the special feature of very long contract durations. Typically operation of over 20 years is expected, during which generation of electricity and revenues are expected. Due to these long operational times, quality, durability, reliability, and degradation rates become crucial for the investment. PV modules are the dominating components in this regard since they prevail the investment. Accelerated ageing tests are in general used to ensure the quality of photovoltaic components. These tests are partly standardized, for PV mainly by IEC and are used for type approval or safety testing. Accelerated ageing tests are also adapted to specific needs and e g used for Quality Assurance (QA) of manufacturers or Service Life Prediction (SLP) by manufacturers or research institutes. All the efforts are taken to gain knowledge about the behaviour of PV modules in operation and thus the accelerated tests have to be related to normal operation. Since PV is used around the globe, the conditions vary significantly depending on the location of installation. In addition, the installation has severe influence on the operational conditions of PV modules. The papers attempt is to give an overview on the state of the art of accelerated testing and field performance analysis of PV modules with focus on developments over the last five to ten years. Developments are described and the status is analysed regarding the significance of tests including the latest developments and open scientific gaps related to the envisaged correlation of accelerated tests with field performance. The reader is enabled to differenciate between reliability testing and service life prediction. The understanding for a comprehensive approach of reliability testing including field evaluation data is develope