Development Of Thermal-electric Coupling Calculation Model And Performance Study For Crystalline Silicon Photovoltaic Curtain Wall

With the rapid development of economy and science and technology,the energy demand is increasing day by day.At the same time,building operation energy consumption accounts for 30%of the global total energy consumption,so building energy conservation is imperative.PV curtain wall is a product of comprehensive utilization of building energy saving and renewable energy.On the one hand,it can reasonably use solar energy to generate electricity,reducing the dependence of buildings on conventional energy,on the other hand,it can also improve the thermal performance of the building envelope,thereby reducing the cooling and heating load of the building during the heating and air conditioning period.In this paper,aiming at the shortcomings of the combined calculation of thermal and electrical properties of PV curtain walls(PVCW)and PV windows(PVW),a thermo-electric coupling calculation model for non-transparent crystalline silicon PV curtain walls(NT-PVCW)and semi-transparent crystalline silicon PV windows(ST-PVW)is established,that is,taking the operating temperature of the PV module as an intermediate variable,through the establishment of an accurate power generation model that can reflect the dynamic power generation efficiency of the PV module,the power generation amount of the PV module is calculated,and then the power generation is used in the energy balance equation of the NT-PVCW or ST-PVW to obtain the temperature at the PV module and other nodes.In this way,the coupling calculation between the heat transfer and power generation models of the NT-PVCW or ST-PVW is repeated until the thermal-electric balance is reached,so as to complete the overall and more realistic simulation calculation of the power generation performance and the heat transfer process of the building envelope in the NT-PVCW and ST-PVW.At the same time,through the establishment of an experimental platform of real-size the NT-PVCW or ST-PVW,a long-term experimental verification of the calculation model under real weather conditions was carried out to ensure the accuracy of the established model.Based on the calculation model established above,the thermal and electrical performance of the NT-PVCW and ST-PVW were simulated.The results show that,in Nanjing,the total heat gain of the NT-PVCW with a peak power of 270 W and 15 mm air layer and ST-PVW with a peak power of 150 W and 46.3%PV cell coverage(PVR)decreased by nearly 24.3%and 19.5%,respectively,compared to ordinary walls and ordinary windows in summer.In winter,the total heat loss of the NT-PVCW decreased by nearly 12.7%,and the total heat loss of the ST-PVW is almost identical with the ordinary windows,while the total solar heat gain decreased by 19.7%.In addition,the NT-PVCW and ST-PVW also have a good electrical performance.Throughout the year,the total annual power generation of the southward NT-PVCW and southward ST-PVW can reached 176.89 k Wh/m~2 and 104.49 k Wh/m~2,respectively.Through further optimization analysis,it was found that the thickness of the air layer and the flow rate of the air layer have a greater impact on the thermal performance of the NT-PVCW.Among them,in summer,when the thickness of the air layer is 10mm,the energy consumption of the air conditioner generated by the heat gain of the NT-PVCW is the smallest,while in winter,when the thickness of the air layer is 1mm,the energy consumption of the air conditioner generated by the heat loss of the NT-PVCW is the minimal.For the air layer flow rate,in summer,the heat gain of the NT-PVCW decreases significantly with the increase of the air layer flow rate.In winter,the heat loss of the NT-PVCW increases significantly with the increase of the air layer flow rate,and when the air layer is closed,the heat loss of the NT-PVCW can be minimized,which is nearly 31.9%lower than that of ordinary wall.For the ST-PVW,the PVR has a greater impact on its thermal performance,and its heat gain decreases with increasing PVR.During the whole year,when PVR≥0.4,the power generation of the ST-PVW in the daytime is greater than the energy consumption of air conditioning caused by its heat gain or heat loss,and when PVR=0.8,the total energy consumption of the ST-PVW is the lowest.For the entire facade of the PV building,the thermal and electrical performance of the crystalline silicon PV curtain wall with different window-to-wall ratios(WWR)will also be significantly different.Comprehensive analysis of the air conditioning energy consumption,lighting energy consumption and power generation of crystalline silicon PV curtain walls with different WWR shows that the total energy consumption of crystalline silicon PV curtain walls decreases with the increase of WWR.When the WWR=0,the total energy consumption of the crystalline silicon PV curtain wall is the largest,reaching 39.59 k Wh/m~2.When the WWR=1,the total energy consumption of the crystalline silicon PV curtain wall is the smallest,reaching 27.11 k Wh/m~2.