The present invention provides a prefabricated floor panel system used in stay in place formwork for pouring concrete floors. The prefabricated floor panel system includes a top and has walls depending downwardly at an upper lateral edge of the wall from each outermost lateral edge of the top, a lower lateral edge of each wall having a ledge extending outwardly away from the top. A first ledge of one prefabricated floor panel system is capable of overlying another ledge of an adjacent prefabricated floor panel system to allow for the one prefabricated floor panel system to be joined to the adjacent prefabricated floor panel system to form a channel. The first ledge of the prefabricated floor panel system is provided with a reinforcing bar spaced away from the wall and the first ledge of the prefabricated floor panel system, the reinforcing bar being supported by a plurality of a reinforcing bar chairs spaced along the length of the prefabricated panel system, the reinforcing bar chairs being attached to the first ledge or wall such that there are no significant interfering structures projecting from a lower surface of the first ledge. The other ledge of the prefabricated floor panel system is free of interfering structures above the ledge to allow the first ledge of one prefabricated floor panel system to overlie the other ledge of an adjacent prefabricated floor panel system to allow for the one prefabricated floor panel system to be joined to the adjacent prefabricated floor panel system to form a channel.