Inclusion of ZnO-based transparent conducting oxide (TCO) film layer into amorphous silicon/crystalline silicon (a-Si/c-Si) solar cell enhances its photovoltaic conversion efficiency. These findings have been confirmed here, using Afors HIT software. The simulation study is performed onto a solar cell that was originallay lab prepared so as to use its measured paramaters in the simulation. The ZnO-based TCO films were electrodeposited on n-type (100) silicon wafer and were simulated. X-ray diffraction (XRD) pattern confirms the zinc blende nature of the TCO layer, and show that the preferred orientation of ZnO films is (002). Scanning electron microscopic (SEM) imaging confirms nano-size nature of the ZnO based TCO film. For comparison purposes, cells with and without TCO layers are investigated by simulating photo-current vs. applied potential (J-V) plots. Values of fill factor (FF), short circuit current density (Jsc) open ciruit potential (VCO) and conversion efficiency (η) are extracted. The energy band diagram,current density and charge carrier generation/recombination phenomena are in-depth analysed to understand the mechanism of enhancement in the hetero-junction cell performance. Values of quantum efficiency(QE)are also simulated.The results show that the solar cell heterojunction is hypersensitive to the ZnO layer. The added value of using the ZnO based transparent conductive oxide (TCO) layer, in enhancing intrinsic thin layer (HIT) solar cell conversion efficiency, is assessed by critically comparing it with a control cell having no ZnO layer.