We present the optical investigation of a novel back-contacted architecture for solar cells based on a thin barium (di)silicide (BaSi2) absorber. First, through the analysis of absorption limits of different semiconducting materials, we show the potential of BaSi2 for photovoltaic applications. Then, the proposed back contacted BaSi2 solar cell design is investigated and optimized. An implied photocurrent density of 40.3 mA/cm2 in a 1-μm thick absorber was achieved, paving the way for novel BaSi2-based thin-film solar cells.