In this paper, an in-depth analysis of the current-voltage characteristics of organic solar cells is performed by introducing a new one-equation model based on a generalised equivalent circuit capable of accurately fitting ideal and non-ideal curves. The model is based on the introduction of a non-linear series resistance term that can be reduced to a linear resistance for the case of ideal curves. A hybrid optimiser approach is proposed combining genetic algorithms and deterministic methods that is shown to facilitate the extraction of the parameters and to accelerate the analysis of the identification problem. Our model is compared with state-of-the-art circuits found in the literature and validated though successful fitting of several experimental curves with differing levels of non-ideal behaviour (such as kinks and s-shape). (C) 2016 Elsevier Ltd. All rights reserved.