Disclosed is a method for determining a solar mask for a facility that comprises a step (E10) of positioning a mobile terminal at a predetermined location of a photovoltaic panel. Following the step (E10), the method comprises a step (E20) of taking a single photograph with a camera of the mobile terminal and a step (E30) of determining an orientation of the camera, during the step (E20), by means of an orientation detection device and a controller of the mobile terminal. The method further comprises a step (E40) of extending at least one contour of the photograph, in at least one direction, and a step (E60) of superimposing data from the extended photograph with a sun path diagram, in a common reference frame, so as to determine the solar mask.