The heterojunction with intrinsic thin-layer (HIT) silicon solar cell has a number of benefits over alternative setups, including low production temperatures and excellent efficiency. Graphene is being investigated by researchers as a transparent electrode for solar systems, with the goal of replacing indium tin oxide (ITO), which has become more expensive and more brittle. Graphene’s exceptional ability to transfer over 97% of incident light, regardless of wavelength, to the underlying solar cell is one of its main advantages over ITO. The detailed photo-generation rates are also observed and EQE in this cell structure is well above 80%. Additionally, a study was done to determine how different performance metrics of an aSi/crystalline silicon (cSi) heterojunction solar cell are impacted by the thickness of the intrinsic hydrogenated amorphous silicon (i-aSi) layer. To model the graphene layer, which functions as the transparent conductive oxide (TCO), 4H-Silicon Carbide (SiC) is used as the base material. Outstanding outcomes were obtained for the optimized graphene-based HIT cell configuration: an open-circuit voltage of 1.198 V, a fill factor of 84.75%, and a short-circuit current density of 29.80 mA/cm2. This configuration exhibits a maximum conversion efficiency of up to 30.25% under AM1.5G light.