A solar concentrator for concentrating sunlight onto a solar receptor, the solar concentrator comprising: a light-guiding slab comprising a light transparent material and having opposing parallel first and second broadside surfaces (122/114), and a luminescent material disposed in the light-guiding slab, the luminescent material being capable of absorbing sunlight having a first wavelength within a first wavelength range and generating light emissions having a second wavelength within a second wavelength range, the second wavelength of said light emissions being longer than the first wavelength, wherein said first and second broadside surfaces (112/114) are formed and the light transparent material is selected such that, when sunlight enters the light-guiding slab and causes the luminescent material to produce said light emissions, at least some of the energy emissions are retained within the light-guiding slab by total internal reflection off of portions of the first and second broadside surfaces (112/114); a plurality of spaced-apart outcoupling structures, each said outcoupling structure being disposed on a corresponding outcoupling region (112R/114R) of one of said first and second broadside surfaces (112/114), each outcoupling structure including a low-absorption, light scattering material disposed on said corresponding outcoupling region such that, when said retained light emissions are reflected onto said said corresponding outcoupling region (112R/114R), said retained light emission is redirected by said each outcoupling structure out of said light-guiding slab; and a plurality of optical elements fixedly secured to the light-guiding slab, each of the optical elements being arranged relative to an associated one of said plurality of outcoupling structures such that at least some of said light emissions passed out of said light-guiding slab by each said one of said plurality of outcoupling structures is directed into said associated optical element, wherein each of the optical elements is formed such that said light emissions are then redirected by said associated optical element in a predetermined direction toward said solar receptor. a light-guiding slab comprising a light transparent material and having opposing parallel first and second broadside surfaces (122/114), and a luminescent material disposed in the light-guiding slab, the luminescent material being capable of absorbing sunlight having a first wavelength within a first wavelength range and generating light emissions having a second wavelength within a second wavelength range, the second wavelength of said light emissions being longer than the first wavelength, wherein said first and second broadside surfaces (112/114) are formed and the light transparent material is selected such that, when sunlight enters the light-guiding slab and causes the luminescent material to produce said light emissions, at least some of the energy emissions are retained within the light-guiding slab by total internal reflection off of portions of the first and second broadside surfaces (112/114); a plurality of spaced-apart outcoupling structures, each said outcoupling structure being disposed on a corresponding outcoupling region (112R/114R) of one of said first and second broadside surfaces (112/114), each outcoupling structure including a low-absorption, light scattering material disposed on said corresponding outcoupling region such that, when said retained light emissions are reflected onto said said corresponding outcoupling region (112R/114R), said retained light emission is redirected by said each outcoupling structure out of said light-guiding slab; and a plurality of optical elements fixedly secured to the light-guiding slab, each of the optical elements being arranged relative to an associated one of said plurality of outcoupling structures such that at least some of said light emissions passed out of said light-guiding slab by each said one of said plurality of outcoupling structures is directed into said associated optical element, wherein each of the optical elements is formed such that said light emissions are then redirected by said associated optical element in a predetermined direction toward said solar receptor.