| As China’s economic level and production capacity continue to improve and the world energy pattern changes,society’s demand for clean energy is further expanding and solar energy is gradually gaining importance,and among these,photovoltaic systems,as the main device for collecting solar energy,are often damaged by wind loads,so it is important to study and analyse the wind load characteristics on photovoltaic panels.At present,the design of PV panel supports is mainly based on the "Regulations for Structural Design of Photovoltaic Mounts" and the "Code for Structural Loading of Buildings",but the reference value of the body coefficient in the code is only for a single PV panel on the ground and is only differentiated on the basis of the tilt angle,and does not take into account the influence of buildings on the wind load characteristics of PV panels,the influence of shading between PV arrays and the influence of other factors on the wind load characteristics of PV panels This is likely to lead to a waste of material and safety problems with the mounting,so it is of great interest to investigate the wind load characteristics of PV arrays on roofs.In this paper,through physical tests and numerical simulation techniques,a series of analytical studies on the wind load characteristics of photovoltaic arrays on flat roofs are carried out,summarising the laws of the influence of building height,daughter wall height and the inclination angle of photovoltaic panels on the wind load characteristics of photovoltaic arrays,and the influence of photovoltaic arrays on the wind load characteristics of roofs,with the following main conclusions.(1)The results of the physical wind tunnel tests of the roof mounted PV arrays through the atmospheric boundary layer show that the test results of the roof mounted PV panels with daughter walls show that the maximum average positive net wind pressure(pressure)on the PV units near the corners of the roof cover is greater than that in the middle area,and the positive wind pressure in the middle area of the front row of PV panels is overall less than that in the middle columns due to the daughter walls.A comparison of the test results for roof panels with different daughter wall heights shows that as the height of the daughter wall increases,the maximum average positive net wind pressure(pressure)on the PV units near the corners of the roof cover decreases significantly.A comparison of the test results for roof panels with different inclination angles shows that for inclination angles less than 10°,the effect of inclination angle on both positive and negative pressures on the roof panels is not significant.The results are also compared with the numerical simulations below to verify the accuracy and feasibility of the numerical simulations.(2)The effect of wind loads on rooftop PV arrays at different building heights was investigated: the change in building height has a very strong effect on the change in wind field environment above the PV array,when H=0m,the absolute values of the resistance coefficient and the overturning moment coefficient of the PV panels are large,especially in the first row reaching a peak,when the building height increases,the absolute values of the resistance coefficient and the overturning moment coefficient will then decrease,and the The overall body coefficient shows a decreasing trend along the incoming flow.The above conclusions provide a reference for practical engineering applications.(3)The effect of wind loads on rooftop PV arrays with different daughter wall heights was investigated: when the daughter wall was installed,the value of the PV array’s form factor increased with the increase in the height of the daughter wall,and the degree of change became more and more dramatic,and the increase in the height of the daughter wall could effectively reduce the form factor,but this effect was limited to when the height of the daughter wall was less than or equal to the height of the PV panels,and when the height of the daughter wall continued to increase,the form factor of the PV As the height of the daughter wall continues to increase,the bulkiness factor of the panels begins to rise.It is recommended that the height of the daughter wall be set at 1-1.5 times the height of the PV panel in order to provide a good shielding effect on the PV panel.(4)The effect of wind load on the PV array at different inclination angles was studied: at 0° wind angle,as the inclination of the PV panel increases,the resistance coefficient and the overturning moment coefficient of the PV array reach their peak at the windward corner,and the body coefficient of the PV array shows a decreasing trend along the incoming flow direction and reaches its peak at the first row.At180° wind angle,as at 0° wind angle,the drag and overturning moment coefficients peak at the windward corner and there is a clear gradient in the bulk coefficient of the PV array.The numerical simulation results of this paper were compared with the relevant codes of China,Japan and the United States,and it was found that the recommended values given by the codes of China,Japan and the United States were all greater than the experimental results of this paper,thus proving the imperfection of the codes and the need for supplementation.(5)The results of the study on the effect of PV arrays on roof wind loads at different building heights show that: at building heights of 10 m and 50 m,with or without PV panels,the values and intervals of the body coefficients of the various roof areas are basically the same,without much change,while at building heights of 25 m,without PV panels,the absolute value of the roof body coefficient decreases significantly,thus It can be concluded that at this height,the installation of photovoltaic panels has a greater influence on the roof form factor.At the same height of the daughter wall,the effect of the installation of PV panels on the roof form factor is not too great,the form factor value only changes slightly,but it is basically within a range,and the change is much smaller than when the daughter wall is not installed.When α=5°andα=55°,the degree of variation of the roof bulk coefficient is significantly weaker than when no PV panels are installed,considering that in these two angles,the PV panels have less interference with the roof flow field and the wind pressure on the roof is more uniform;when 10°≦α≦40°,the installation of PV panels has a greater impact on the roof wind pressure and the roof wind field changes more drastically,and from an overall perspective,the peak value of the bulk coefficient for each The peak of the body coefficient under the angle is basically in the corner area.Figure [53] table[13] reference[82]... |
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