Surface photovoltage (SPV) method is a contactless technique for non-destructive characterization of Si wafers and monocrystalline Si solar cells, mainly for minority carrier diffusion length determination. The minority carrier diffusion length, L is a critical factor impacting the conversion efficiency and spectral response of the monocrysyalline Si solar cell and it is also essential for evaluation of the quality and transport properties of the P-type Si wafer. In 1961, A. M. Goodman showed that, under certain assumption, by making measurements of SPV as a function of wavelength, the minority carrier diffusion length can be determined. Therefore a simply steady state SPV method has been developed to determine the minority carrier diffusion length as well as lifetime of monocrystalline Si solar cells. In Bangladesh for the first time "Bangladesh Atomic Energy Commission (BAEC)" has set up a laboratory to fabricate and diagnosis of monocrystalline Si solar cell. This paper focused on the study of surface photvoltage (SPV) and determination of minority carrier diffusion length, L and lifetime, ? of monocrystalline Si solar cell. By calculating the experimental data obtained from monocrystalline Si solar cells measurements, minority carrier diffusion length and lifetime were derived and it was 81.5?m and 2.5?sec respectively.