Plasmonic effects of various sized Al nanospheres non-embedded on Ta2O5 antireflective–coated single-junction GaAs solar cells are analyzed by finite difference time domain (FDTD) simulations. The impact of optimized plasmonic nanoparticles is further analyzed for embedded Al nanospheres in GaAs and compared with nanoparticles at back contact. It is found that the nanoparticles of radius 30 nm show superior spectral response in comparison with other radii for non-embedded design. Further, non-embedded optimized nanoparticles show better spectral response when embedded in GaAs layer 10 nm below the Ta2O5 antireflection layer, which yields a maximum current density of 28.17 mA/cm2. Moreover, photovoltaic current–voltage characteristics were studied to confirm the performance enhancement induced by Al nanoparticle plasmons. The power conversion efficiency enhancement of 5.4, 11.5, and 2.3% for optimized radius of 30 nm in non-embedded, embedded (at optimized depth of 10 nm), and at rear surface, respectively, were found compared to Ta2O5-coated single-junction GaAs solar cells. [ABSTRACT FROM AUTHOR]