Dye-sensitized solar cells (DSSCs) are inexpensive to manufacture and easy to process in comparison with silicone solar cells, but they are difficult to commercialize due to their low efficiency. Accordingly, the aim of this study was to improve the efficiency of a DSSC via an aluminum film reflective plate, reusing discarded light after it was absorbed. We found that the factor having the most dominant influence on DSSC efficiency was the amount of radiation reacting with the dye. For a reflective plate with [symbol: see text] = 30° and h = 15 mm, DSSC efficiency was increased about three times.