The invention relates to a reflective device for a photovoltaic module formed by a plurality of bifacial photovoltaic cells or rows of said cells spaced apart from one another, each cell having an active front face and an active rear face that can capture photons from incident light rays falling on the front and rear faces. The device comprises at least one reflective module to be placed under the cells substantially in line with the gap(s) separating two adjacent cells or two rows of adjacent cells. The reflective module comprises: a first portion, of which the surfaces that are oriented towards the gap have a first curvature such as to send all or part of the incident photons towards the rear face of the cells; and a second portion mounted on the first portion, of which the surfaces oriented towards the gap have a second curvature such as to send all or part of the incident photons towards the rear face of the cells, the second curvature being different from the first curvature.