The atomically thin flat sheet of carbon atoms, 'graphene' showcases several key features that can address emerging energy needs, in particular to enhance the energy conversion efficiency of photovoltaic devices. Here, we review the energy conversion efficiency of graphene incorporated solar cell devices. The various structures of the solar cell devices have been investigated which includes organic, inorganic and hybrid structures. Dye sensitized solar cell with Gr/PEDOT:PSS counter electrode has exhibited 4.5% efficiency, which is comparable to expensive Pt counter electrode based device with 6.3% power conversion efficiency. The Gr/Silicon nano-hole and Gr/Silicon nanowires based Schottky junction devices have revealed high efficiency of 8.71% and 10.30%, respectively. In bulk hetero-junction solar cell devices, GO as electron transport layer has increased performance from 5.9% to 7.5%. The GO/PEDOT:PSS as hole transport layer in planar hetero junction perovskite photovoltaic device of structure ITO/(GO/PEDOT:PSS)CH3NH3PbI3/PCBM have achieved 9.7% efficiency, which is greater than 8.2% of traditional PEDOT:PSS. Though graphene shows great potential for photovoltaic applications, its stability and flexibility are also equally important and have been discussed. The results indicate that utilization of graphene in energy devices yields more efficient results and opens new avenues for future applications.