This International Standard series lays down IEC requirements for the design qualification of terrestrial photovoltaic modules suitable for long-term operation in open-air climates. The actual lifetime expectancy of modules so qualified will depend on their design, their environment and the conditions under which they are operated. Test results should not be construed as a quantitative prediction of module lifetime. In climates where 98th percential operating temperatures exceed 70 °C, users may want to consider testing to higher temperature test conditions as described in IEC TS 63126. This standard is intended to apply to all crystalline silicon terrestrial flat plate modules. This standard does not apply to modules used with concentrated sunlight although it may be utilized for low concentrator modules (1 to 3 suns). For low concentration modules, all tests are performed using the current, voltage and power levels expected at the design concentration. The object of this test sequence is to determine the electrical characteristics of the module and to show, as far as possible within reasonable constraints of cost and time, that the module is capable of withstanding prolonged exposure outdoors. The actual lifetime expectancy of modules so qualified will depend on their design, their environment and the conditions under which they are operated. Accelerated test conditions are empirically based on those necessary to reproduce selected observed field failures and are applied equally across module types. Acceleration factors may vary with product design and thus not all degradation mechanisms may manifest. Further general information on accelerated test methods including definitions of terms may be found in IEC 62506. This standard defines PV technology dependent modifications to the testing procedures and requirements per IEC 61215-1 and IEC 61215-2.