Study On Physical Properties Of Multi-layer Photovoltaic Vacuum Glass

Ecological and environmentally friendly building materials are regarded as the focus of future reforms in the construction market around the world.As a green renewable resource,solar energy is almost inexhaustible.Therefore,solar power has been widely used in my country.The use of densely distributed urban buildings combined with solar equipment to generate electricity can reduce the pressure on the entire urban power grid system.Therefore,in recent years,the application of photovoltaic technology in buildings has developed rapidly,and the BIPV technology is the perfect combination of solar photovoltaic modules and buildings.However,because of the poor thermal conductivity of traditional photovoltaic glass,poor lighting,thereby reducing the overall performance of photovoltaic building integration technology.In order to obtain more excellent performance photovoltaic modules,in recent years,many researchers have shown great interest in the research of the combination technology of photovoltaic glass and vacuum glass,the development of photovoltaic vacuum glass technology has attracted great attention in the application of photovoltaic building integrated engineering.In recent years,the international research focus on reducing the thermal conductivity of photovoltaic vacuum glass,the materials supported by the vacuum interlayer and the stress,and the transmittance of visible light.This thesis is based on the multi-layer photovoltaic vacuum glass designed by the Sino-British cooperation project,the following research contents had been completed:1.This thesis introduces an innovative thin-film photovoltaic vacuum glass technology.In the application of integrated photovoltaic equipment in buildings,the optical properties of photovoltaic glass are important for determining the solar light transmission and heat transfer process of the overall glass system.This thesis discusses the optical properties of photovoltaic vacuum glass by considering the different unit layers of photovoltaic vacuum glass including self-cleaning glass,thin-film photovoltaic glass and low-e glass.Based on the optical transfer matrix,the transmission coefficients of different functional layer glasses were derived.The theoretical calculations were then validated against the transmission coefficient experiment of the photovoltaic vacuum glass using an EDTM SS2450 Solar Spectrum Meter.The calculation error of the transmission coefficient of single-layer glass is generally within 5%,and the calculation error of the transmission coefficient of the integrated photovoltaic vacuum glass is about6%.The results show that the visible light transmittance,infrared light transmittance and total transmittance of photovoltaic vacuum glass are 8%,22%and 11%,respectively.2.The COMSOL software was used to establish a three-dimensional model of the photovoltaic vacuum glass sample,and the three-dimensional model was set to a certain pressure.With changing the number of SiO₂ aerogel support columns and the elastic modulus of the SiO₂ aerogel support column material and the height and the radius of the support column,the stress distribution and deflection distribution of photovoltaic vacuum glass were analyzed.The results show that:?1?The increase in the number of SiO₂ aerogel support pillars is conducive to improving the overall performance of photovoltaic vacuum glass;?2?After the height of the support column exceeds 0.25mm,increasing the height of the SiO₂ aerogel support column will deteriorate the glass compression resistance and deflection.Increasing the radius of the SiO₂ aerogel support column will improve the overall performance of the photovoltaic vacuum glass;?3?The stress on both sides of the photovoltaic vacuum glass is large,and the stress in the middle is small,while the stress on the support columns on both sides of the vacuum interlayer is small,and the stress in the middle is relatively large.3.The comprehensive performance of two groups of photovoltaic vacuum glass samples was tested in a real environment,the external surface temperature,internal surface temperature,power generation and U value of the glass were analyzed.After the evaluation of the sample of photovoltaic vacuum glass made by the British partners,the following results can be obtained:the average temperature of the outer surface and inner surface of the 0.3m×0.3m photovoltaic vacuum glass,the average U value are 10.9?,24.2?,and 1.61W/m²·k,respectively.After the evaluation of the sample of photovoltaic vacuum glass made by the China Hanergy,the following results can be obtained:the average temperature of the outer surface and inner surface,the average power and U value of the 0.4m×0.4m photovoltaic vacuum glass are 12.51?,22.48?,9.8W and 0.51W/m²·k,respectively.Under certain solar radiation,each square meter of photovoltaic vacuum glass produces a maximum power of 12.7W/m².Compared with traditional PV glass with a typical U value of about 5W/m²·k,the overall U value of photovoltaic vacuum glass has been increased by 90%.The results also show that the U value of the photovoltaic vacuum glass made by the Chinese side is better than that of the photovoltaic vacuum glass made by the British side.The Photovoltaic vacuum glass not only can generate electricity,but also has high insulation performance.The research results of this paper provide guidance for the application of photovoltaic vacuum glass in the integration of photovoltaic buildings.