Renewable energy is major agenda to reduce the Carbon Emissions the world. Photovoltaic energy has high potential to achieve the goal. One of issue in Photovoltaic is increase the power density, in which, bifacial module is took account. Bifacial modules have the optical advantage of greater light collection compared to mono-facial modules. Therefore, bifacial photovoltaic technology has been receiving increasing interest because it promises a higher performance yield and lower levelized cost of energy than mono-facial photovoltaic (PV) technology. Herein, the effect of the bifacial module was compared with that of the monofacial module of a floating photovoltaic located in the valley of a reservoir near a Dam in South Korea. The system consisted of a mono-facial module, bifacial modules, a micro-inverter for checking the power of each module, and insolation for measuring the irradiation and reflection of water. Consequently, the bifacial gain with power generation of the bifacial PV was 4% ~ 5% and the performance ratio was 3.8% ~ 4%. The bifacial gain with only water reflection was maximum 2.74%.