Optic group for a lighting system including a plurality of solid state light sources, includes a plurality of optics each positionable in proximity of at least a correspondent solid state light source, a planar housing matrix of the plurality of optics for facilitating assembly of the lighting system. The assembling method includes sequentially: a) rotating at least a first asymmetric optic with respect to a third axis, parallel to a longitudinal axis of at least a correspondent solid state light source, at a first predetermined angle measured with respect to an axis orthogonal to the third axis, so as to lead the first asymmetric optic in a first configuration which is rotated with respect to the third axis and centered over the correspondent housing; b) coupling the first asymmetric optic to a correspondent housing of the planar housing matrix, and maintaining the same in the first rotated configuration.