Two applications of porous silicon in the photovoltaic solar cell technology were investigated. The light-trapping effect was verified in porous silicon covered wafers by spectral transmission and photoresponse measurements. In this case, micron-size pores act as efficient scatterers for the incoming radiation. A thin nanoporous layer, which has a refractive index lower than that of silicon, was used for antireflection coating of the solar cells. The increase of the short-circuit current by nearly 30% after a porous layer application has been observed.