Chalcogenide perovskites (CPs), especially Barium Zirconium Sulfide (BaZrS3), have attracted tremendous attention as a potential alternative to hybrid halide perovskites for optoelectronics due to their exceptional visible light absorption and extraordinary chemical stability. Therefore, we numerically investigated a highly efficient n-i-p CPs model solar cells using the Solar cell simulator capacitance software (SCAPS-1D), consisting of a conventional (i.e., BaZrS3 – 1.9 eV), as well as Ti and S, incorporated absorbers (i.e., Ba(Zr0.95Ti0.05)S3 – 1.63 eV and BaZr(S0.6Se0.4)3–1.76 eV). The systematic studies explored the varying CPs absorber layer properties, the effects of thickness, total and interface (i.e., ETL/CPs and CPs/HTL) defect densities and optimized parameters for ideal device performance. The optimized solar cell parameters yielded a power conversion efficiency (PCE) of 12.42% for BaZrS3, 18.85% for Ba(Zr0.95Ti0.05)S3 and 15.47% for BaZr(S0.6Se0.4)3 devices, respectively. The study also explored some effects limiting device performance (i.e., interface and surface states) and resultant current leakages or charge recombination, leading to parasitic resistances (RSeries and RShunt). The quantification of the influence of parasitic resistances and working temperatures provided some insight into the device performance, which appear to be reduced with increasing operating temperature and series resistances. These results suggest that chalcogenide BaZrS3 - based perovskites can play a major role as absorber materials towards highly efficient and cheap perovskite solar cells with low environmental impact.