In October 2011, a commercialized 100kW class floating photovoltaic system positive plant was installed at Hapcheon dam a multi-purpose reservoir the first time ever in the nation. Floating photovoltaic system differs in water float, mooring device and underwater cable process from land photovoltaic system. As for land and building photovoltaic power generation equipments, many installation cases and skilled experiences are available, and thus installation is not difficult. However, commercial power generation floating photovoltaic system, which is attempted for the first time in the nation, requires to be designed and installed through a series of processes like technical review and verification of data by process in comparison with similar cases. The structure of floating photovoltaic system, an equipment for float photovoltaic module and other electrical equipment, is required to withstand weather environments like wind or typhoon etc and yet not affect water quality negatively, and for implementation of this system, construction efficiency and economy etc should be considered comprehensively. In this paper, the techniques of installing floating photovoltaic structure, mooring device, underwater cable, electrical equipment and remote monitoring control system are explained. The 100kW floating PV system is operating with 15% average capacity factor

-In solar generation, the PV array's azimuth is headed due south and the tilt is generally 33° in order to acquire maximum generation. However, when installed in a site where there are buildings or other facilities, the azimuth and tilt are adjusted. Yet, when the azimuth and tilt are deviated from due south and 33°, the generation quantity is decreased substantially and currently a method to estimate the decreasing proportion is unavailable. Therefore, in this thesis, an equation on the "change ratio of solar radiation due to the changes in tilt and azimuth" was deduced by utilizing empirical data on the amount of solar radiation received according to the changes of tilt and azimuth and Interpolation. By using this equation, the decreasing proportion of generating quantity due to the installation methods of PV system can be estimated, therefore, it can be usefully utilized when designing and going through feasibility studies for development of solar generation systems.

K-wa t e rI n s t i t u t e ,Ko r e aWa t e rRe s o u r c e sCo r p o r a t i o n 수상환경의 대지저항률 및 접지저항 측정의 실험적 연구Abstract Main ground net of power plant is formed to protect human body from increase in potential gradient caused by grounding current during ground fault. Calculations during ground design are generally performed according to IEEE Std-80-2000 (Kepco Design Standard 2602. However, it is difficult to apply this Standard to water environment, and a grounding technology is required to secure grounding resistance of floating photovoltaic system. Therefore the aim of this paper is to investigate and analyze ground resistivity on the water surface and underwater of reservoir using Wenner 4-pin method, a general method of measuring ground resistivity. Also, grounding resistance of floating photovoltaic systems currently in operation was measured and analyzed using the voltage drop method suggested in the international standard (IEEE Std-81) to propose a grounding method for stable grounding of floating photovoltaic system. The resistivity at 1m below the surface of water (126.3969 [Ω․m]) is mostly higher than resistivity at the river bed (97.5713 [Ω․m]). Also the proposed grounding anchor method was determined as the most effective method of securing stable grounding resistance in floating photovoltaic systems and is expected to be utilized as a ground method for future floating photovoltaic generation systems.

-Floating photovoltaic systems have been developed by the construction process such as design, construction, operation and management. Therefore, the power of floating photovoltaic systems has been calculated by using simple formulas and the optimal tracking interval is set by operation experience. But, flow characteristics have a decisive effect on it unlike land based PV systems. In this paper, a tracking floating photovoltaic system is modeled by using Matlab/simulink. The modeling for the floating photovoltaic system is verified through applying the flow characteristics based on actual operating data of 100㎾ class tracking floating photovoltaic.

For the development of a floating photovoltaic system, materials with light weight and high tensile strength must be applied to reduce the burden on buoyancy, and material characteristics with high resistance to corrosion in water environment is required. Accordingly, a new high strength steel material with improved strength, durability, manufacturability, and weldability that are appropriate for floating photovoltaic system structures is needed. This paper reports the results of a mechanical load test and steel corrosion test on general steel (SS400) and high strength steel (POSH 690) for the selection of an appropriate steel material for a floating photovoltaic system. The results of a test on new high strength steel revealed excellent mechanical performance compared to general steel. The new steel material was manufactured for use in an actual site, and the weight was reduced by approximately 30∼40% compared to existing general steel.