A non-tracking solar energy collector comprising: (a) at least one solar radiation concentrator configured to direct 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 configured to let solar radiation rays to enter said external cavity, said reactive reflector having at least one transparency zone instantly formed at said at least one focal point of the solar radiation rays beyond intensity threshold, and said at least one transparency zone 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 configured to trap 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 capable of preventing solar radiation to dissipate from said solar cell, thereby minimising solar radiation losses; wherein said reactive reflector comprises: (a) a separator film (or spacer sheet) having an opening filled with a suspension of highly reflective microparticles, such as metal-coated glass microspheres having a mean diameter in the range of about 1-100 μm, preferably silver-coated or aluminium-coated, in a liquid, such as water, and (b) two optically transparent slides (44, 45), the first optically transparent slide being attached at the bottom of said separator film forming a solid support for said reactive reflector, and the second optically transparent slide being attached at the top of said separator film covering said opening, wherein said separator film is squeezed between two said optically transparent slides (44, 45), thereby forming a sandwich-like structure. (a) at least one solar radiation concentrator configured to direct 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 configured to let solar radiation rays to enter said external cavity, said reactive reflector having at least one transparency zone instantly formed at said at least one focal point of the solar radiation rays beyond intensity threshold, and said at least one transparency zone 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 configured to trap 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 capable of preventing solar radiation to dissipate from said solar cell, thereby minimising solar radiation losses; wherein said reactive reflector comprises: (a) a separator film (or spacer sheet) having an opening filled with a suspension of highly reflective microparticles, such as metal-coated glass microspheres having a mean diameter in the range of about 1-100 μm, preferably silver-coated or aluminium-coated, in a liquid, such as water, and (b) two optically transparent slides (44, 45), the first optically transparent slide being attached at the bottom of said separator film forming a solid support for said reactive reflector, and the second optically transparent slide being attached at the top of said separator film covering said opening, (a) a separator film (or spacer sheet) having an opening filled with a suspension of highly reflective microparticles, such as metal-coated glass microspheres having a mean diameter in the range of about 1-100 μm, preferably silver-coated or aluminium-coated, in a liquid, such as water, and (b) two optically transparent slides (44, 45), the first optically transparent slide being attached at the bottom of said separator film forming a solid support for said reactive reflector, and the second optically transparent slide being attached at the top of said separator film covering said opening, wherein said separator film is squeezed between two said optically transparent slides (44, 45), thereby forming a sandwich-like structure.