PERFORMANCE EVALUATION OF HIGH EFFICIENCY PHOTOVOLTAIC POWER-GENERATION SYSTEM EQUIPPED WITH A COOLING DEVICE

近年来，光伏发电系统作为一种清洁能源备受关注。尤其是随着人们对全球变暖的日益关注和光伏制造成本的持续下降，与电网相连的住宅屋顶光伏系统得到了普及，光伏组件产生的功率随着辐照度的增加而增加，但随着光伏组件温度的升高而减少。光伏温度取决于环境温度，夏季达到60℃以上。因此，即使夏季光照度增加，发电量也不一定增加，但如果在如此高的光伏温度条件下对光伏组件进行冷却，光伏组件将获得更多的电能。该系统的主要组件是一组光伏组件和连接到光伏组件背面的冷却面板。各个光伏组件用流经每个冷却面板上的狭窄缝隙的冷却水进行冷却。从冷却板排出的热水被输送到储水箱，可以在任何地方重复使用。为了节省将冷却水引入面板的能源，采用了从建筑物上层到地面的虹吸。虹吸管连接到冷却板的排气口，因此排气口的压力变为负值。冷却水在常压下进入冷却板的底端，向上到达顶部，排出侧。通过采用这种冷却水系统，可以将冷却水均匀地分布在光伏组件的整个背面，从而实现有效的冷却装置。结果证实，光伏组件的冷却增加了电能，冷却板热水的再利用对节约热水消耗有很大的贡献。

Recently, the photovoltaic (PV) power generation system has attracted attention as one of clean energies. Especially, residential roofing PV system connected with power grids has been popularized as a result of increasing concerns over global warming and continuing decline in PV manufacturing costs.The power generated by the PV module increases with irradiance, but it decreases as PV module temperature becomes high. The PV temperature depends on ambient temperature, and becomes more than 60℃ in summer. Therefore, the power generated does not necessarily increase even if tit irradiance increases in summer However, if the PV modules were cooled under such a high PV temperature condition, more electrical power would be obtained from PV modules.In this study, a PV power generating system equipped with a cooling device has been developed. The major components of the system are an array of PV modules and cooling panels attached to the backside of the PV modules. The respective PV module is cooled with cooling water flowing through a narrow gap in each cooling panel. Hot water discharged from the cooling panel is delivered to a storage tank and can be reused in anywhere. In order to save energy for introducing cooling water into the panel, siphonage from an upper level of a building to the ground level is utilized. A siphon tube is connected to a discharge port of the cooling panel, thus the pressure at the discharge port becomes negative. Cooling water enters into the bottom end of the cooling panel at atmospheric pressure and goes up to the top, discharge side. By adopting this cooling water system, we could spread the cooling water evenly over the entire backside of the PV module and thus realized an effective cooling device.As a result, it was confirmed that the cooling of the PV modules increases the electric power and that the reuse of hot water from the cooling panel contributes very much for saving energy consumed for heating water.