Abstract: An apparatus includes a light concentrator, which during operation directs light from an entrance aperture and an exit aperture, and a photovoltaic device positioned relative to the exit aperture to receive the light. The light concentrator includes a hollow body formed from a pair of spaced-apart sidewalls and an exit wall connecting the sidewalls, each sidewall being formed from a material having a first refractive index, n1, the exit wall includes a first element having an exit surface positioned at the exit aperture, the first element being formed from a material having second refractive index, n2, and the hollow body contains a liquid having a having a refractive index n3, where n3<n1 and n3<n2.