NOVELTY - The concentrator has a set of solar cells (3a, 3b) for receiving solar energy and converting the solar energy into electrical energy, where the solar cells are positioned relative to light transmissive substrates (2). A set of slits (4) i.e. split shorter air slits, is arranged in the substrates. Each slit directs light incident on a side of the corresponding substrate to one of the solar cells on an opposite side of the substrate. The slits are assigned to the solar cells, respectively. The slits have a refractive index being less than a refractive index of the substrate.    USE - Transparent solar concentrator for use in a window system (claimed) i.e. see-through photovoltaic window system, of a building, for converting solar energy into electrical energy. Can also be used in a building integrated photovoltaic (BIPV) field, a solar powered mobile device, a green house, a conservatory and a sun rove.    ADVANTAGE - The solar cells can be easily fabricated. The concentrator is featured with improved incident angle dependent performance. The substrates containing the light redirecting elements and photovoltaic cells can be laminated between other substrates so as to protect environment from damage, humidity and UV radiation. The light redirecting elements alter direction of light incident on the light redirection element, where the elements are formed via strips or grooves formed in the substrate, and can be filled with air to provide a lower refractive index so as to achieve total internal reflection. The cells can be used to collect light with different spectrums where light from wider incident angles has a different spectrum of light from low angle, so that different solar cells can be used to capture light with different spectrums to increase the conversation efficiency of the window system. The concentrator uses resin to attach protective glass sheets to the substrate and a solar cell panel to provide better protection from damage and water. The gap between the redirecting elements can be filled with transparent glue to reduce the surface reflection loss, and to gain mechanical performance.    DETAILED DESCRIPTION - The solar cells are formed as a set of photovoltaic strips, where each strip is spaced apart from an adjacent strip by a predetermined distance. An INDEPENDENT CLAIM is also included for a method for creating a solar concentrator.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a concentrator with multiple solar cell strips in a section to collect light with different spectrums.    Incident angles (1h, 1l)    Light transmissive substrate (2)    Solar cells (3a, 3b)    Substrate light redirecting elements (4)