Devices, systems, and methods are provided for both retrofitting existing lighting fixtures with LED panels and for installing ceiling tiles having LED modules incorporated therewith. In one exemplary embodiment, a thin panel includes an LED module integrated therewith and the panel is disposed over an opening in a troffer to provide light from the panel-module combination. In another exemplary embodiment, a ceiling tile includes an LED module integrated therewith and the tile is placed in a ceiling grid so light can be provided from that tile. Exemplary configurations of the systems, devices, and kits, as well as methods for installing the same, are also provided.