Extraction of a photovoltaic cell's double-­diode model parameters from data sheet values

Abstract

In the data sheets of photovoltaic cells, manufacturers usually only provide selected points of the cell's current-­voltage curve, that is, short-­circuit current, open-­circuit voltage and current and voltage at the maximum power point. However, these three parameters do not suffice to deduce the cell's double diode model parameters. Thus, it is not possible to reproduce the complete current-­voltage characteristics. Here, we point out how the range of the double diode parameters can be determined from the available data points and present approximately valid conditions which can be exploited to derive unique double diode parameter sets. The introduced methods rely on the solution of one-­dimensional equations and the intervals within which their roots lie are established. Thus, a straightforward extraction of the parameters is possible. The reliability of four different methods is checked by comparison with real cells whose double diode parameters are known for varying temperature and illumi- nation conditions as well as with numerically generated parameters. Accurate parameter guesses and a faithful reproduction of the cell's IV-­curve can be achieved, in particular, for present-­day high-­quality cells.