An improved five-parameter model for photovoltaic modules

This paper presents a new five-parameter model capable of analytically describing the I–V characteristic of a photovoltaic module for each generic condition of operative temperature and solar irradiance. The parameters of the equivalent electrical circuit are extracted by solving a system of equations based on data commonly issued by manufacturers in standard rating conditions with a trial and error process. The procedure, which does not require any special equations solver, can be easily coded into a short software routine using simple languages and finds the solution of the system of equations with the desired accuracy without needing to be guided towards solutions starting from fitted initial values of the searched parameters. In particular, as implemented in VBA macros in Microsoft Excel, the model provides the most accurate results with a rapid convergence. To verify the capability of the new model to fit PV panel characteristics, the procedure was tested on two different panels. Results were compared with the data issued by manufacturers and with the results obtained using five-parameter models proposed by other authors.