| With the rapid rise of photovoltaic agriculture,photovoltaic(PV)agriculture integration is attracting more and more attention from the photovoltaic industry and agriculture.However,due to the lack of research on the combination of the two at the present stage,the phenomenon of low yield of agricultural production and the change of agricultural land has been caused by the consideration of power generation.Therefore,how to balance photovoltaic power generation and agricultural production has become a serious and complex problem that we have to solve.In this paper,we make the photovoltaic tea garden with fixed tilted plane in Hangzhou,Zhejiang province as the research object,and simulate the lighting environment of the photovoltaic tea garden by using the Ladybug software,and evaluate the lighting environment from the aspects of shading degree,the solar radiation uniformity and the photosynthetically active radiation.PVsyst software is used to calculate the power generation capacity of photovoltaic tea garden.The specific contents and conclusions are as follows:(1)The distribution solar radiation intensity of the photovoltaic tea garden at the height of the tea canopy was simulated by the Ladybug software.The solar radiation is bright and dark alternately in the middle area of the tea garden where is not affected by the side light from south to north.And the shading degrees under the PV panels and between two PV panels are 28.04%?42.5%and 23.98%?37.97%,respectively.And the solar radiation uniformity of this PV tea garden is 75.63%.(2)The relationship between the solar radiation intensity,the light compensation point and light saturation point of the PV tea garden in 12 to 13 o'clock period from May to August was analyzed.Because of the spacing of photovoltaic panels,the minimum solar radiation intensity is much smaller than the maximum solar radiation at the same time.The maximum solar radiation intensity in the PV tea garden exceeds the light saturation point of the tea tree,and the minimum solar radiation intensity is lower than the light compensation point of the tea tree.There is 83,43,83 and 31 days from 12 to 13 in 123 days,the maximum solar radiation intensity of the tea garden is higher than the light saturation point of "Fu Ding","Long Jing 43","Fu Yun" and "Ku Ding".There is 9 days from 12 to 13 in 123 days,the minimum solar radiation intensity of the tea garden is lower than the light compensation of "Ku Ding".(3)With fixed photovoltaic tea garden as the reference,the lighting environment of seven fixed photovoltaic tea gardens were compared and analyzed.When the distance between two adjacent PV panels in the east-west direction is between 992mm?2500mm,the solar radiation uniformity is between 66.74%?82.84%.And under PV panels,the minimum shading degree in the area where is not affected by side light is between 18.2%?39.97%,and the maximum shading degree is between 27.6%?59.93%.Under the two adjacent PV panels,the minimum shading degree of the solar radiation is between12.61%?23.98%,and the maximum shading degree of the solar radiation is between 22.98%?37.97%.Moreover,when the distance between two adjacent PV panels is between 1500mm and 2500mm,the shading degree of solar radiation are negatively correlated with the distance between adjacent panels.Therefore,the lighting environment of photovoltaic tea garden can be changed by increasing the distance between adjacent objects in the east-west direction.(4)With fixed photovoltaic tea garden as the reference tea garden,the lighting environment of eight fixed photovoltaic tea gardens were compared and analyzed.When the distance between two adjacent PV panels in the east-west direction is between 3000mm-6500mm,the solar radiation uniformity is between 65.28%?75.63%.And under PV panels;the minimum shading degree in the area where is not affected by side light is between 4.93%?28.04%,and the maximum shading degree is between 32.79%?42.50%.Under the two adjacent PV panels,the minimum shading degree of the solar radiation is between 4.24%?23.98%,and the maximum shading degree of the solar radiation is between30.56%-37.97%.When the distances between two adjacent PV panels varies from 3000mm to 6500mm,the shading degree and the solar radiation uniformity decrease with the increase of the distance between the PV panels in the north-south direction.(5)With fixed photovoltaic tea garden as the reference tea garden,the lighting environment of three fixed photovoltaic tea gardens were compared and analyzed.And under PV panels,the minimum shading degree in the area where is not affected by side light is between 17.%-29.15%,and the maximum shading degree is between 41.37?56.39%.Under the two adjacent PV panels,the minimum shading degree of the solar radiation is between 16.22%?24.77%.And the maximum shading degree of the solar radiation is between 36.32%?47.92%.When the center of the PV panel is 1.8 meters,2.8 meters and 3.8 meters away from the ground,the solar radiation uniformity is 52.05%,75.63%and 77.94%,respectively.With the increase of the central height of the PV panel,the solar radiation uniformity of the PV tea garden is also increased,and the effect is very significant when the PV module rises from 1.8 meters to 2.8 meters.(6)The power generation of the PV systems with different distances between PV panels are simulated by the PVsyst software.When the distances between two adjacent PV panels in the direction of east and west are 992,1500,1700,1900,2100,2300 and 2500,the unit land area power generation are 117.08,81.20,72.50,65.51,59.66,54.82 and 50.72 kWh/m2,respectively.When the distances between two adjacent PV panels in the direction of north and south are 3000,3500,4000,4500,5000,5500,6000,6500mm,the unit land area power generation are 81.20,70.99,62.73,56.38,51.19,46.85,40.02,40.02 kWh/m2,respectively.With the increase of the distances between two adjancent PV panels,the annual power generation of the PV system increases.However,the power generation per unit land area decreases.(7)The distribution solar radiation intensity of the photovoltaic tea garden with horizontal single-axis tracker at the height of the tea canopy was simulated by the Ladybug software.The solar radiation is bright and dark alternately in the middle area of the tea garden where is not affected by the side light from west to east.And in this area the shading degree is between 32.86%?48.98%.And the solar radiation uniformity of this PV tea garden is 75.99%,and it is beneficial to the uniform growth of the tea tree.(8)The relationship between the solar radiation intensity,the light compensation point and light saturation point of the PV tea garden with horizontal single-axis tracker in 12 to 13 o'clock period from May to August was analyzed.There is 34 days from 12 to 13 in 123 days,the minimum solar radiation intensity of the tea garden is lower than the light compensation of "Ku Ding".There is 86,31,45 and 86 days from 12 to 13 in 123 days,the maximum solar radiation intensity of the tea garden is higher than the light saturation point of "Fu Ding","Ku Ding","Long Jing 43" and "Fu Yun".(9)Considering the same installed capacity on the same land area(4500mm ×3000mm),the power generation capacity of the PV system with the fixed titled plane and PV system with horizontal single-axis tracker is compared.The power generation of PV system with horizontal single-axis tracker is 10.72%higher than that of PV system with fixed titled plane.From the perspective of generating capacity,PV system with horizontal single-axis tracker has great advantages in improving land use efficiency and economic benefits. |
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