Performance evaluation of IEC 60891:2021 procedures for correcting I–V curves of photovoltaic modules under healthy and faulty conditions

Abstract

Correction of PV modules' current–voltage characteristics (I–V curves) is essential before they can be used for performance analysis and fault diagnosis under real-life conditions. IEC 60891 (version 2021) has updated Procedure 2 and proposed a new correction Procedure 4 compared to the 2009 version. This study aims to analyze the performance of these new procedures applied to I–V curves of faulty PV modules. The work is based on an mc-Si PV module considering healthy and four common fault conditions with varying fault severity. The irradiance and temperature measured in the field are used to generate I–V curves. The correction procedures of IEC 60891 (version 2021) based on a single curve (Procedures 1, 2, and 4) are evaluated. Environmental factors such as measurement season and irradiation level on the correction performance are studied. The results show that Procedure 2 is relatively better with the relative root-mean-square error of the curve current as 2.6% compared to Procedure 1 (2.8%) and Procedure 4 (4.8%). Experimental tests using real I–V curves also show that Procedure 2 exhibits better robustness of correction. The new Procedure 4, whose correction coefficients are determined dynamically, performs poorly under partial shading and short-circuit bypass conditions. However, it achieves similar or better performance than Procedures 1 and 2 under degraded conditions, where the PV fault is generally not easy to detect, making the I–V correction more necessary. It is, therefore, a promising alternative correction procedure when it is difficult to determine the correction coefficients in advance. Finally, the pros and cons of the procedures are discussed with the suggestion of correction procedures under different conditions. The challenges and prospects are also provided.