In hybrid solar cells consisting of dye sensitizers incorporated in the i-layer of a microcrystalline silicon (μc-Si:H) pin solar cell the dye sensitizer molecules are embedded in the matrix and enhance the overall absorption of the dye-matrix system due to their high absorption coefficient in the spectral range interesting for photovoltaic applications. This contribution investigates the efficiency improvement of hybrid dye-μc-Si:H solar cells compared to pure μc-Si:H solar cells by simulation. The results indicate that, under optimum conditions, the efficiency can be improved by more than a factor of 1.2 compared to a pure μc-Si:H cell. The thickness reduction for the hybrid system can be as large as 50 % for the same efficiency. However, the efficiency improvement also depends on the amount of additionally induced defects in the matrix by the embedded dye molecules. Therefore, the simulations investigate the performance of the hybrid solar cell for different absorption enhancements and defect densities.