NOVELTY - Self-tracking solar concentrator system for capturing solar light of the sun, where the solar light comprises a short wavelength light component and a long wavelength light component, comprises at least a lens, a light-guide, and a self-adaptive coupling feature, where at least one lens is arranged adjacent to the light-guide in order to focus the long wavelength component onto the self-adaptive coupling feature, and the self-adaptive coupling feature is configured to couple the short wavelength light component into the light-guide.    USE - The systems are useful for capturing solar light of the sun; and for collecting and transporting sunlight for day lighting purposes within building structures (all claimed).    ADVANTAGE - Device structure and physical mechanism that allow a solar concentrator to self-track the sun, or follow the sun's position reactively, are provided. This self-tracking mechanism allows for solar concentrator systems including: (1) a solar concentration system without any external active mechanical tracking; or (2) a solar concentrating system with coarse mechanical alignment for which fine alignment is achieved by the self-tracking mechanism.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a solar photovoltaic system comprising the system for capturing solar light of the sun that self-tracks the sun and collects direct sunlight into a photovoltaic cell;    (2) a system for collecting and transporting sunlight for day lighting purposes within building structures comprising the system for capturing solar light of the sun; and    (3) a method for capturing solar light from the sun, where the solar light comprises a short wavelength light component and a long wavelength light component, the method involves focusing the solar light onto a self-adaptive coupling feature, where a location of the focused solar light on the self-adaptive coupling feature is dependent of the position of the sun, absorbing in the self-adaptive coupling feature the long-wavelength light component, thus locally heating up the coupling feature and creating a localized coupling feature, coupling the short wavelength light component into a light-guide at the localized coupling feature, and transporting the short wavelength light component through the light-guide to its edge.