This part of IEC 60904 describes procedures for the measurement of the current-voltage characteristics of multi-junction photovoltaic devices in natural or simulated sunlight. It is applicable to single PV cells, sub-assemblies of such cells or entire PV modules. It is principally intended for non-concentrating devices, but parts may be applicable also to concentrating multi-junction PV devices. An essential prerequisite is the spectral responsivity of the multi-junction devices, whose measurement is covered by IEC 60904-8-1. The requirements for measurement of current-voltage characteristics of single-junction PV devices are covered by IEC 60904-1 whereas this standard describes the additional requirements for the measurement of current-voltage characteristics of multi-junction PV devices. NOTE: This standard may be applicable to PV devices designed for use under concentrated irradiation if they are measured without the optics for concentration and irradiated using direct normal irradiance and a mismatch correction with respect to a direct normal reference spectrum is performed.