Original Article

Accessible spectral calibration of multi-LED solar simulators for tandem I–V measurement

¹ Solar Energy Research Institute of Singapore, National University of Singapore, Singapore
² École Polytechnique, Palaiseau, France
³ École Centrale Méditerranée, Marseille, France
⁴ Department of Mechanical Engineering, National University of Singapore, Singapore

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 10 July 2025
Accepted: 3 March 2026
Published online: 6 May 2026

Abstract

Reproducing the AM1.5G reference spectrum using solar simulators in the laboratory is essential for accurate and transparent reporting of the I–V performance of perovskite-based tandem solar cells, a fast-growing technology approaching commercialization. The International Electrotechnical Commission (IEC) has specified the spectral calibration requirements for tandem devices in IEC 60904-1-1: Photovoltaic devices – Part 1-1: Measurement of current-voltage characteristics of multi-junction photovoltaic devices. However, practical implementation of these standards using multi-LED solar simulators can be challenging. This study shares a method to calibrate multi-LED solar simulators for tandem devices, with code implementation. This method was developed to satisfy the IEC-defined mismatch factor (M) and matching factor (Z) thresholds, which quantify how accurately the solar simulator reproduces the reference spectrum for tandem device measurement. The method is validated on three perovskite–silicon tandem solar cells, all of which achieved |1–M|<5% and |1–Z|<3% for both sub-cells, fulfilling the IEC’s criteria. By sharing this method and code-implementation, this study aims to increase the accessibility of standard-compliant solar simulator calibration.