Iterative methods for solving g-functions: a review, comparative evaluation, and application in the solar cell domain

The voltage–current characteristics of solar cell models, regardless of the equivalent circuits used, are nonlinear functions that can be mathematically represented by the g-function. Computational modeling plays a key role in solving such complex functions, enabling accurate simulations and efficient solutions that are essential for optimizing solar cell performance. This paper first provides a comprehensive overview and comparative evaluation of several iterative methods used to solve the g-function. Next, the accuracy of these iterative methods across both positive and negative values of the functional argument is assessed. The number of iterations required to achieve the desired accuracy is then analyzed, along with the influence of accuracy on the number of iterations. Additionally, the computation times of all the observed methods are examined, along with the impacts of the initial values on the required number of iterations. Finally, the paper demonstrates the application of the proposed iterative methods for voltage calculations within a single-diode model of solar cells. The findings suggest that the Halley iterative method demonstrates superior efficiency, requiring fewer iterations for accurate results and lower computation time, whereas the Newton and Ostrowski methods yield similar performance. MATLAB codes for each iterative method discussed are provided, ensuring their applicability for addressing various engineering challenges related to the g-function.