Hybrid organic/inorganic nanocomposite solar cells are a potential candidate as an alternative to photovoltaic (PV) devices based on semiconducting inorganic or organic nanomaterials. In a recent study, carried on ITO/PVK:n-TiO2/Al structures, we have observed a performance degradation due to bipolar charge recombination and space-charge formation. Then, a simulation of I–V characteristics of photovoltaic (PV) diodes for different organic nanomaterials suggested replacing poly (N-vinylcarbazole) (PVK) by poly (3-hexylthiophene-2,5-diyl) P3HT. In this work, we have studied the current–voltage characteristics of ITO/PEDOT:PSS/P3HT:SiNW/Al solar cell under white illumination with different volume ratios (10%, 20%, 50%) of SiNW. The results have shown a maximum FF for 20% silicon nanowire (SiNW) volume ratio corresponding on the one hand to the morphology exhibiting the lowest RMS and on the other hand the maximum quenching of PL spectra. A degradation of the PV properties is induced at higher composition by the formation of larger of SiNW aggregates. Procedures have been developed to extract the different parameters from I–V characteristics under illumination in the basis of an equivalent circuit. The variation of the photogenerated current with SiNW volume ratios confirms that the PV response is optimum for 20 vol% SiNW.