The second enclosure 122 may include coupling holes CPH1 to CPH4 that are spatially connected to the module fastening holes MH1 to MH4 and fastened by a module screw 130, as illustrated in FIG. 8. The number of coupling holes CPH1 to CPH4 of the second enclosure 122 may correspond to the same number of module fastening holes MH1 to MH4. The coupling holes CPH1 to CPH4 of the second enclosure 122 may overlap the module fastening holes MH1 to MH4 and the coupling grooves CPG1 to CPG4 of the first enclosure 121 corresponding thereto. Although the planar shapes of the coupling holes CPH1 to CPH4 of the second enclosure 122 and the module fastening holes MH1 to MH4 may be the same, embodiments are not limited thereto.
The second enclosure 122 may include bottom fastening pillars LB1 to LB4 in which the coupling holes CPH1 to CPH4 are located, as illustrated in FIG. 3. If there are four coupling holes CPH1 to CPH4, four bottom fastening pillars LB1 to LB4 may also be provided. That is, the first enclosure 121 has a first bottom fastening pillar LB1 placed at the first corner CNR1, a second bottom fastening pillar LB2 placed at the second corner CNR2, a third bottom fastening pillar LB3 placed at the third corner CNR3, and a fourth bottom fastening pillar LB4 placed at the fourth corner CNR4.
