Simplified Approach to Adjust IEC-60891 Equation Coefficients From Experimental Measurements With Long-Term Validation

Modeling photovoltaic modules using the single-diode model presents an adequate balance between complexity and accuracy; however, the current-voltage characteristic has to be calculated every time the operating condition changes. In turn, IEC-60891 provides procedures for direct translation from one operating condition to another, allowing a more straightforward application, provided that specific parameters are known. That international standard describes a procedure to quantify such parameters; however, their calculation requires complex equipment or extensive experimental tests. This article presents an alternative and simplified method to compute the parameters of IEC-60891, specifically the second procedure presented in the standard. It requires a reduced amount of measurements to be used as references. The validation of the method has been carried out taking extensive experimental data as reference, considering thousands of measurements taken for 16 months. The application of the proposed method to translate the reference curves presented mean absolute error and root-mean-square error below 3%, considering two different photovoltaic modules.