A combination for illuminating the interior of a building comprises a fixture and a retrofit kit. The fixture has a base attached to a building ceiling, the fixture having a first tombstone, and a second tombstone. The first and second tombstones are configured to receive between them a fluorescent light tube. The retrofit kit is connected to the base. The retrofit kit includes a light panel, the light panel having a first side facing the fixture and an opposite second side. The light panel resides between the first tombstone and the second tombstone, and the fixture resides above the light panel. The combination is devoid of a fluorescent light tube. The base and the light panel define between them a raceway. A light emitting diode is disposed on the second side of the light panel.