IEC 61215-1-4:2021 is available as IEC 61215-1-4:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition. IEC 61215-1-4:2021 lays down requirements for the design qualification of terrestrial photovoltaic modules suitable for long-term operation in open-air climates. The useful service life of modules so qualified will depend on their design, their environment and the conditions under which they are operated. Test results are not construed as a quantitative prediction of module lifetime. This document is intended to apply to all thin-film Cu(In,Ga)(S,Se)2 based terrestrial flat plate modules. As such it addresses special requirements for testing of this technology supplementing IEC 61215-1:2021 and IEC 61215-2:2021 requirements for testing. This second edition cancels and replaces the first edition of IEC 61215-1-4, issued in 2016. This edition includes the following significant technical changes with respect to the previous edition: a. A cyclic (dynamic) mechanical load test (MQT 20) added. b. A test for detection of potential-induced degradation (MQT 21) added. c. A bending test (MQT 22) for flexible modules added. This standard is to be read in conjunction with IEC 61215-1:2021 and IEC 61215-2:2021.