Plasmons in noble metallic nanoparticles can be used in order to increase efficiency of energy transfer in solar cells of various configurations, mainly in diode-type setups. The origin of plasmonic effect is still not fully recognized and one of the important contributions to photocurrent enhancement results from the inclusion of non-conserved momentum interband transition in semiconductor as a consequence of absence of translational invariance in nanomodified system. We consider energy transfer efficiency via plasmons in nanoparticles and its dependency of nanoparticle radius. Fully-analytical, semiclassical approach for plasmons in spherical geometry is applied and efficiency of near-field absorption in semiconductor is estimated upon Fermi's golden rule. Finally, we link our results with experimental measurements of photocurrent gain in semiconductor silicon-diode setup with gold nanoparticles, which occur in positive qualitative agreement with the theoretical predictions. (C) 2013 Elsevier B.V. All rights reserved.