Accurate solution to the nonlinear parameters of solar energy mathematical model has a great influence on the accuracy of solar cell output power calculation, but it is difficult to obtain. Moreover, these parameters will also change as the environment or battery life changes. A method is proposed to accurately solve the nonlinear parameters of photovoltaic cells based on Newton-Raphson method with limit constraints. This method uses Newton-Raphson method to iteratively solve the exact solution of the nonlinear parameters. The limit constraints are used to effectively solve the problem that the stiffness of the Jacobian matrix is not converged due to the improper selection of the initial value, which makes convergence faster and can realize the real-time online exact calculation of the nonlinear parameters for the currently operating photovoltaic cell. A single-diode four-parameter mathematical model is built, and the fourth-order Jacobian matrix is deduced, and the limit constraint is given. Finally, the feasibility and validity of the proposed method are demonstrated by two example experiments.
Keywords Nonlinear parameters, solar energy, Newton Raphson method, Jacobi matrix, limit constraints