A photovoltaic solar power plant assembly and a method of using the assembly to generate power are disclosed. The assembly includes an array of photovoltaic solar modules arranged in a solar module surface, and an optical structure for redirecting light towards the solar module surface, having redirected light emitting surface. The optical structure includes a planar optical waveguide which has a parallel first and second planar waveguide surfaces, wherein the first planar waveguide surface extends parallel to the redirected light emitting surface, wherein the first planar waveguide surface is at least partially covered by a photonic layer which is configured to provide an angular restriction of a light emission from the planar waveguide through the redirected light emitting surface, a light scattering and/or luminescent material, which material is arranged as particles in the planar optical waveguide and/or in a layer which at least partially covers the second planar waveguide surface.