This article presents a study of plasmonic effect from small size silver nanoparticles in Sibased solar cells. The particles have been deposited on the surface of Si by thermal evaporation method. Size of the particles and its distribution on number of particles has been studied by the scanning electron microscope. It is shown that the largest particle size we got was ~32 nm. The samples have been capped by SiO x or SiN x and reflectance spectra have been measured. We found that the reflectance decreases with increasing the silver nanoparticle diameter. Annealing at 375 o C did not cause qualitative change of the reflectance spectra. The particles have been deposited on Si solar cells and current-voltage dependence has been measured.