A concentrating photovoltaic (CPV) cell exhibits the highest conversion efficiency among any solar cells. However, the further enhancement of the CPV efficiency is strongly limited by the heat generation at high solar concentrations. Here, we demonstrate a concentrating photovoltaic/thermoelectric hybrid generator using a single-junction, GaAs-based solar cell and a conventional thermoelectric module as a model system. Our hybrid generator gives rise to the conversion efficiency larger than the single CPV cell by ~3% at the solar concentration of 50 suns. Controlling thermal flow in the hybrid generator and the Peltier cooling effect is the key to achieving high efficiency. Our result provides a framework for designing a highly-efficient hybrid generator using both photo-electric and photo-thermal effects for the clean-energy production.