The development of thin film solar cells on cheap substrates requires new approaches to enhance the cell efficiency. In the present work we analyse solar cells with porous silicon diffuser arrays in the form of pipes within the deposited silicon layer. The contribution of Rayleigh scattering on full randomized nanosize crystallites of porous silicon pipes to the cell efficiency was simulated depending on the pipe geometry, their depth in the silicon film, surface recombination rate and diffusion length. The simulation shows that the efficiency improvement, due to the performance of light trapping, achieves significant values at the technical attainable characteristics of the porous layer. The effect of light trapping increases with the insertion of pipe arrays close to the rear side of the cell and for Si films having a low diffusion length. The work states that the geometric dimensions of pipes drastically alter the benefit of this cell design.