Generator assembly systems and methods of manufacturing and operating generator assembly systems. The generator assembly system includes a generator enclosure, a diesel engine, an aftertreatment exhaust system, a primary diesel exhaust fluid system, and an auxiliary diesel exhaust fluid system. The primary diesel exhaust fluid system includes a primary diesel exhaust fluid storage tank fluidly coupled to the aftertreatment exhaust system. The auxiliary diesel exhaust fluid system includes an auxiliary diesel exhaust fluid storage tank and a transfer pump fluidly coupled to the auxiliary diesel exhaust fluid storage tank. The auxiliary diesel exhaust fluid system is housed in an auxiliary enclosure positioned outside of the generator enclosure. At least one fluid conduit fluidly couples the transfer pump to the primary diesel exhaust fluid storage tank.