Abstract We demonstrate diffractive rear side gratings to enhance the near infrared light trapping and thus the quantum efficiency of wafer based crystalline silicon solar cells. Binary crossed gratings with a period of 1 µm, produced via nanoimprint lithography and plasma etching, are electrically decoupled from the solar cell by a thin dielectric passivation layer, creating an electrically flat, but optically rough rear side. We fabricated solar cells with thicknesses of 250, 150 and 100 µm and demonstrate a short circuit current density gain due to the grating of 1.2, 1.6 and 1.8 mA/cm 2 for solar cells with planar front surface. For solar cells with pyramidally textured front surface the grating also leads to a small current density gain in the near infrared of approximately 0.3 mA/cm 2 according to EQE measurements, leading to the best cell's efficiency of 21.1%. By optical simulations we show the potential of the grating structure and identify losses in the fabricated solar cells.