Abstract: The present disclosure relates to an inspection system, in particular a mobile inspection system, for outdoor inspection of photovoltaic modules in situ, the inspection system comprising a movable detector unit and a processing unit. The detector unit is configured to obtain, when positioned at a user-controllable position spaced apart from a photovoltaic module of a photovoltaic power system, luminescence data from a light-receiving surface of said photovoltaic module. The detector unit may include a light source, in particular a laser source, configured to emit an illumination beam, means for selectively directing the illumination beam onto respective portions of the light-receiving surface so as, when the illumination beam is directed onto a first portion of the light-receiving surface, to only illuminate the first portion while leaving a corresponding first remaining portion of the light-receiving surface unilluminated by the illumination beam.