IEC 60904-9:2020

Overview

IEC 60904-9:2020 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the classification system for solar simulators used in photovoltaic (PV) testing and calibration. This standard is essential for laboratories and manufacturing facilities that perform indoor measurements of terrestrial photovoltaic devices, including solar cells and PV modules.

The document focuses on classifying solar simulators based on three critical performance characteristics:

• Spectral distribution match
• Irradiance non-uniformity in the test plane
• Temporal instability of irradiance

Solar simulators are categorized into Class A+, A, B, or C, with Class A+ representing the highest standard primarily used in calibration laboratories. A simulator that does not meet the minimum Class C requirements cannot be classified under this standard.

This third edition, replacing the 2007 edition, introduces significant updates such as an extended wavelength range for spectral match classification, a new A+ class, revised measurement procedures, and additional requirements for spectral irradiance evaluation apparatus.

Key Topics

• Solar Simulator Classification
  The standard defines the criteria for assigning solar simulators into four classes-A+, A, B, and C-based on their ability to replicate the solar spectrum and maintain consistent test conditions. An accurate classification enables consistent and reliable photovoltaic device testing.

• Spectral Distribution Match
  Solar simulators must reproduce the solar spectral irradiance closely within specified wavelength ranges. IEC 60904-9:2020 extends spectral match classification to an extended range of 300 nm to 1200 nm and introduces additional parameters to evaluate spectral irradiance.

• Irradiance Non-Uniformity Measurement
  The standard lays out procedures and apparatus requirements to measure irradiance uniformity across the test plane. Uniform illumination is critical to ensure repeatable and accurate photovoltaic device performance testing.

• Temporal Instability of Irradiance
  Solar simulators must exhibit minimal fluctuation in irradiance during the measurement period. IEC 60904-9:2020 differentiates requirements depending on whether the simulator is for current-voltage (I-V) measurements or for irradiance exposure.

• Measurement Uncertainty and Procedures
  The standard details systematic procedures for evaluating the solar simulator’s characteristics and quantifies uncertainties associated with spectral match, spatial uniformity, and temporal stability.

• Informative Annex for Sensitivity Analysis
  Annex A provides guidance on analyzing the spectral mismatch error related to solar simulator spectral irradiance, which is beneficial for determining the impact on PV device measurement accuracy.

Applications

IEC 60904-9:2020 applies primarily to:

• PV Test and Calibration Laboratories
  Ensures high measurement accuracy needed for calibrating primary and secondary reference devices in laboratory conditions.

• Solar Cell and PV Module Manufacturing
  Defines performance criteria for solar simulators used in production lines to verify device quality and power output under standard test conditions.

• Performance and Endurance Testing
  Provides classification for simulators used in electrical characterization and long-term irradiation endurance tests of photovoltaic devices indoors.

• Calibration of Reference Devices
  The introduction of Class A+ supports lower uncertainty in calibrations, improving the reliability of subsequent measurements in manufacturing environments.

This standard ensures that measurement results are traceable, reproducible, and harmonized internationally, which is crucial to enhancing performance consistency and market confidence in photovoltaic technologies.

Related Standards

• IEC 60904-1 – Defines requirements for general photovoltaic device measurements.
• IEC 60904-3 – Specifies reference solar spectral irradiance distributions for test conditions.
• IEC TR 60904-14 – Provides best practice recommendations for production line measurements and reporting of maximum power output of single-junction PV modules under standard conditions.
• IEC 60904 Series – Comprehensive series on photovoltaic device testing methods and terminology.

Together, these standards provide a robust framework for solar simulator evaluation, photovoltaic device testing, and quality assurance across the solar energy industry.

Keywords: IEC 60904-9:2020, solar simulator classification, photovoltaic testing, spectral distribution match, irradiance uniformity, temporal instability, solar cell calibration, photovoltaic module manufacturing, solar simulator standards, PV device measurement