Morphological, optical and electrical properties of SiNWs are studied under different preparation conditions. Despite an ultra-low reflectivity revealing a high light-trapping effect, we obtained a degradation of the resistivity and the minority carrier lifetime in SiNWs which are ascribed to a high electron-trapping. For solar cells application, we determine a trade-off between optical and electrical properties of SiNWs. However, even with this optimization, we obtained a degradation of the electrical parameters of the solar cell when SiNWs are used as compared to the cell without SiNWs. From the obtained results in this work, we put in evidence for the first time that despite the very low reflectivity that a SiNWs film has, its use in PV is faced to four major challenges; (1): an unbalancing between the length of SiNWs and the electron diffusion length, (2): a thick SiO2 layer covering silicon wires formed during the solar cell processing (observed using dark field transmission electron microscopy), (3) a high density of dangling bonds of porous-SiNWs when the SiO2 film is etched, and, (4) a poor metal/SiNWs front contact. (C) 2014 Elsevier Ltd. All rights reserved.