a system includes a solid light - transmissive element comprising a first surface and a second surface , first reflective material disposed on the second surface of the light - transmissive element , and a solar cell to convert light received at the first surface to electrical current . the light received at the first surface may pass through the light - transmissive element , reflect off the first reflective material and intercept an area of an interface between the first surface and an adjacent environment at an angle of incidence greater than arc sin , where n x = an index of refraction of the adjacent environment and n y = an index of refraction of the light - transmissive element at the first surface .