Microcrystalline p-i-n silicon devices are a prospective contender for application in large-area optoelectronics. In this paper we analyse the behaviour of a mu c-Si:H p-i-n photodevice under non-uniform illumination. The effect of a spatially non-uniform illumination is to create lateral electric fields and current flows inside the structure. We present in this paper a numerical application of a complete bidimensional model describing the transport properties within the structure. The continuity equations for holes and electrons together with Poisson’s equation are solved simultaneously along the two directions parallel and perpendicular to the junction. The results of simulating p-i-n mu c-Si:H junctions under non-uniform illumination show that the generated lateral effects depend not only in intensity but also in direction on the wavelength of the incident radiation.