| Under the background of energy crisis and environmental pollution, photovoltaic technology have been widely used and rapidly developed, due to its clean and safety features. However, it still has shortcomings of low efficiency and high cost. To solve these problems, layout structure of photovoltaic power generation system was changed. In this paper, the fixed type photovoltaic power generation system was selected as the research object and additional reflectors with different structures were placed between the PV modules. Based on the principle of optical reflection and refraction, it is found that reflectors can effectively improve the generating capacity of PV power system and reduce the total generation cost by increasing the solar radiation on the PV modules, thus achieving improvement and optimization on the performance of photovoltaic system.Firstly the roof photovoltaic power generation system experiment platform and real-time data acquisition system were designed in this paper. Then, the system was verified on the plane reflectors, non planar reflectors, the reflectors’material and the reflectors’spatial arrangement through experiments. The research indicates that the optimal layout emerges when the silver mirror planar reflector has an inclined angle of 28.7° from the horizontal, the hypotenuse length is 1236mm, the horizontal distance between the low margin and the rear PV modules is 339mm and the vertical distance between the low margin and the ground is 396mm, in this condition, the effective generating capacity of PV modules can be increased by about 20%. Besides, the cost of this reflector is only 0.4 Yuan per watt (a nearly 4% increase in construction costs).Using the experimental data and the simulation, the reason to make the PV modules’ generation increase by additional reflectors was analyzed. The analysis reveals that, in poor lighting conditions, the reflector produces a greater increase in the generating capacity of PV modules. In addition, the growth amplitude of the PV modules’ generating capacity is in correspondence with variation tendency of the scattering radiation share in solar radiation. This phenomenon indicates that the mechanism how reflectors increase the generating capacity is mainly ascribed to the reflection of scattering light to the PV modules’ surface.Based on experimental data collected from the photovoltaic power generation system during a year, the PV modules’ power output characteristic was analyzed from different time scales of year, mouth and day. The analysis shows that annual power output characteristic of PV modules is discontinuous and mutational.PV modules’ monthly power output varies apparently in different seasons.In Nanjing area, compared with winter and rainy summer, it is spring, early summer and autumn that PV modules have much more power output. Daily power output varies depending largely on weather conditions. In sunny weather, PV modules have larger power output peak and higher overall power output, whose power output curve is more smooth; In the conditions of overcast sky, generate electricity output curve of PV modules fluctuates largely, showing multimodal characteristics; While in partly cloudy day the output curve is intermittent; However, under rainfall conditions PV modules have short power generation output time and low output peak, whose power output curve fluctuates greatly. In addition, PV modules’ power output characteristics affected by other environmental factors including solar irradiance, air temperature and wind speed were researched in this paper. The results show that solar irradiance has the greatest influence on the power output of PV modules. In the meanime, it is found that the power output of PV modules has evident positive correlation with atmospheric temperature, but no regular relation with the wind speed. However, the growth of the PV modules’ output power will be compressed when the atmospheric temperature exceeds the certain value. |
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