Study On Photoelectric And Thermal Properties Of Dynamic Concentrating Solar Building Skin

With the continuous improvement of building energy consumption,environmental and energy issues are getting worse.Sustainable design idea has gradually become the mainstream design idea.Today’s building demand not only requires energy conservation,but also takes into account the energy production function.Therefore,sustainable and productive building skin is the demand and trend of building development.Because the energy output can offset or even exceed the energy consumption of the building itself,the productive green ecological building has gradually become a new research focus.Solar energy,as a renewable energy,is easy to obtain.At the same time,as the third generation of high-efficiency solar energy technology,the application of solar energy to building skin will bring about changes in artistic expression,structural form and energy characteristics.At present,the research of domestic and foreign scholars mainly focuses on the photoelectric characteristics of the single concentrator photovoltaic module.Based on the study of the photoelectric characteristics of the newly designed concentrator photovoltaic module,this paper studies the solar radiation distribution and thermal performance of the Concentrating Solar Building Skin.The research results are as follows.In this paper,the optical properties of the concentrating solar building skin and the concentrator photovoltaic module are simulated and analyzed using Trace Pro software.The optical and electrical properties of the module are tested experimentally.The simulation results show that the focal spot size of the primary concentrator is 15mm×15 mm,and the energy loss of the secondary concentrator is 4.1%.The effect of tracking error on the concentrating efficiency can be ignored if tracking error less than±0.5°,and the corresponding concentrating efficiency can reach 78.1%.The test results show that the actual focal spot size of the primary concentrator is 25 mm×25mm under tracking error of±0.5°,which means that part of the energy is not concentrated on the secondary concentrator,therefore the actual concentrating efficiency is 69.0%.The generation efficiency of solar cell is maintained at 37.9%,and the operation efficiency of the module is maintained at 26.1%.The heat transfer process,influencing factors and evaluation index of the dynamic concentrating solar building skin are analyzed.According to the heat transfer process,the energy balance equation and thermal resistance model of the skin are established,and the calculation method of the comprehensive heat transfer coefficient of the skin is obtained.The size of skin is simulated and optimized by Fluent software.The simulation results show that the optimum channel width and the optimum vent width of the concentrating skin are 0.5m and 0.2m respectively.The comprehensive heat transfer coefficient K=1.179 W/（m2.K）;the average wind speed inside the channel is 0.52 m/s;the ventilation volume N_air=0.395 m³/s;the exhaust heat Q_air=143.70 W;and the average temperature of the cell is 59.81℃,which is 15.07 C lower than that without ventilation.The performance of the concentrating solar building skin is better than that of the traditional double skin.The research results of this paper can provide design guidance and data basis for the related research and application of BICPV.