On the homogeneity of the external quantum efficiency in a free OPV roll-to-roll flexible solar module

•We investigate the uniformity of the optical and photovoltaic properties of an organic photovoltaic module.•Good uniformity of the external quantum efficiency on a scale of ∼0.4 mm2 is found (variations ∼6-8% of the peak value).•Higher differences are found between different cells of the module (up to 1.6 times).