Here it is shown that silicon absorbs visible light:
but the band gap energy for direct transitions is 3.6 eV which does not match to this absorption coefficient. Instead, the band gap energy for an indirect transition is 1.12 eV. Hence, I assume, the visible light must excite silicon through indirect transitions. Is that correct? If so, how does this work? Why is visible light being able to lift an electron from the valence up into the conduction band?