IEC 60904-2:2023 gives requirements for the classification, selection, packaging, marking, calibration and care of photovoltaic reference devices. This document applies to photovoltaic (PV) reference devices that are used to measure the irradiance of natural or simulated sunlight for the purpose of quantifying the electrical performance of photovoltaic devices (cells, modules and arrays). It does not cover photovoltaic reference devices for use under concentrated sunlight. This fourth edition cancels and replaces the third edition published in 2015. This edition includes the following significant technical changes with respect to the previous edition:a) added calibration procedures for calibrating PV devices at maximum power by extending the respective Clauses 12 and 13;b) revised requirements for mandatory measurement of spectral responsivity, temperature coefficients and linearity, depending on usage and allowing some measurements on equivalent devices;c) revised requirements for built-in shunt resistor;d) added requirements for traceability of calibration explicitly.