IEC 60904-1:2020 describes procedures for the measurement of current-voltage characteristics (I-V curves) of photovoltaic (PV) devices in natural or simulated sunlight. These procedures are applicable to a single PV solar cell, a sub-assembly of PV solar cells, or a PV module. This document is applicable to non-concentrating PV devices for use in terrestrial environments, with reference to (usually but not exclusively) the global reference spectral irradiance AM1.5 defined in IEC 60904-3. This third edition cancels and replaces the second edition published in 2006. The main changes with respect to the previous edition are as follows: - Updated scope to include all conditions. - Added terms and definitions. - Reorganised document to avoid unnecessary duplication. - Added data analysis clause. - Added informative annexes (area measurement, PV devices with capacitance, dark I-V curves and effect of spatial non-uniformity of irradiance).