Retrofit systems which replace the entire optical systems of the existing luminaire and fully integrate a replacement light source, optics, and reflective panel, where the panel connects with the fixture housing front along two opposing sides or more and when installed, fully conceals the interior of the existing housing. These retrofit kits may not employ existing lamp holders or “pin” bases, and retrofit kits that have exposed LEDs, tube style lenses, or bar-style components are not eligible.