The optical absorption coefficient of crystalline silicon near the band edge is determined to values as low as 10−7cm−1by sensitive photocurrent measurements on high efficiency silicon solar cells. Structure due to three‐ and four‐phonon assisted absorption processes is observed. Discrepancies between absorption coefficient values around 10−2cm−1reported in the literature are resolved. The role of disorder theory in understanding the absorption edge of crystalline semiconductors such as silicon is discussed. ©1995 American Institute of Physics.