We applied a global sensitivity analysis (GSA) to a PV performance tool to describe the influence of four parameters (orientation, tilt, distance between rows and albedo, along with the interaction effects between them) on two intermediary results of the estimation: yearly effective irradiance and yearly energy generation. In the case of yearly effective irradiance, the most influential factors where orientation, distance between rows and tilt, in order of influence, followed by two interaction effects between them. For the yearly energy output, the most influential factors where distance between rows, orientation and tilt, with the first parameter noticeably exceeding the rest of influence sources. We underlined the importance of using this information to obtain relevant visual representations of the model’s behaviour.