A Global Nonlinear Model for Photovoltaic Modules Based on 3-D Surface Fitting

The main objective of this work is to propose a global nonlinear model (GNLM), valid under varying solar irradiance (
G
) and temperature (
T
) conditions, generating characteristic curves that closely replicate the actual behavior of the evaluated modules. The proposed GNLM incorporates a technique that combines surface polynomial fitting based on numerical optimization. This integration results in the creation of unique adaptable surfaces for each parameter, providing them with flexibility. Additionally, the research also aims to investigate other nonlinear global models for photovoltaic modules and conduct a comparative study of accuracy. The proposed model demonstrated significantly superior results compared with the best model evaluated in the literature for xSi modules, with a normalized mean absolute error in power (NMAEP) percentage difference of 98.21% and a normalized root mean square deviation (NRMSD) difference of 25.60%. In contrast, for mSi modules, the results showed a slight improvement over the same model, with an NMAEP percentage difference of 26.19% and an NRMSD difference of 1.52%. Similarly, for CdTe modules, there was an NMAEP percentage difference of −0.84% and an NRMSD difference of 12.82%.