The present application describes embodiments of a non-tracking solar energy collector comprising: (a) at least one solar radiation concentrator for collimating and directing the incident solar radiation rays to at least one focal point along the surface of a reactive reflector; (b) the reactive reflector mounted on top of an external cavity and having at least one transparency zone instantly formed at said at least one focal point of the solar radiation rays, for letting the solar radiation rays enter said external cavity, wherein said transparency zone is constantly moving along the surface of said reactive reflector following the position of said at least one focal point of the solar radiation rays; and (c) the external cavity containing a solar cell and capable of trapping the entered solar radiation rays by inner scattering of said solar radiation rays on the walls of said external cavity, wherein said inner scattering of said solar radiation rays inside said external cavity is preventing solar radiation to escape from said solar cell, thereby minimising solar radiation losses.