Photovoltaic conversion was enhanced by directly assemble of a network of single-walled carbon nanotubes(SWNTs) onto the surface of n-p junction silicon solar cells. When the density of SWNTs increased from 50 to 400 tubes μm~(-2), an enhancement of 3.92% in energy conversion efficiency was typically obtained. The effect of the SWNTs network is proposed for trapping incident photons and assisting electronic transportation at the interface of silicon solar cells. Photovoltaic conversion was enhanced by directly assembling a network of single-walled carbon nanotubes (SWNTs) onto the surface of np junction silicon solar cells. When the density of SWNTs increased from 50 to 400 tubes μm -2, an enhancement of 3.92% in energy conversion efficiency was typically obtained. The effect of the SWNTs network is proposed for trapping incident photons and assisting electronic transportation at the interface of silicon solar cells.