Panels of LED arrays and LED lighting systems are described. A panel includes a substrate having a top and a bottom surface. Multiple backplanes are embedded in the substrate, each having a top and a bottom surface. Multiple first electrically conductive structures extend at least from the top surface of each of the backplanes to the top surface of the substrate. Each of multiple LED arrays is electrically coupled to at least some of the first conductive structures. Multiple second conductive structures extend from each of the backplanes to at least the bottom surface of the substrate. At least some of the second electrically conductive structures are coupled to at least some of the first electrically conductive structures via the backplane. A thermal conductive structure is in contact with the bottom surface of each of the backplanes and extends to at least the bottom surface of the substrate.