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不同光伏阵列结构遮阴对光环境及小麦产量的影响

Effects of photovoltaic array shading on light environment and wheat yield

  • 摘要: 光伏农业作为一种清洁能源生产与农业空间高效利用的复合土地利用模式,其光伏组件引发的光热环境异质性会显著影响作物光合作用与产量形成。然而,针对不同支架形式对光伏农业系统内部光环境及作物产量的影响尚不明确,这已成为制约该模式推广的关键科学问题。该研究以内部种植冬小麦的光伏农业系统为试验对象,重点探究不同光伏方阵结构对系统内光环境特征及作物生理响应的影响机制。通过设置固定式支架与追踪式支架两种光伏结构的田间对比试验,采用太阳辐射强度传感器连续监测全生育期内不同种植区域(光伏板下与板间区域)的太阳辐射强度变化,同步测定小麦叶片光合参数及产量构成因子。试验数据显示,光伏系统内部光环境存在显著的空间异质性特征。固定式支架区域板间采光率达到84.5%,显著高于板下区域的37.1%(P<0.05);而追踪式支架区域板间区域(56.8%)与板下区域(53.4%)太阳辐射强度差异未达显著水平。遮阴效应导致各处理组平均产量较对照组下降58.7%~61.1%,其中固定式支架区(2 973.3 kg/hm2)与追踪式支架区(3 198.2 kg/hm2)产量水平基本持平。值得关注的是,追踪式支架较固定式支架的光伏组件铺设密度高出3.0%,然而前者的单位面积发电量可提升13.2%。研究表明,追踪式支架技术能够在维持作物生产力的同时显著提高能源产出效益,展现出更强的农光协同发展潜力。该研究为农业光伏系统的光环境调控提供了方法学支撑,相关成果可为地方政府制定农光互补项目政策、以及新能源企业优化系统设计方案提供科学依据。

     

    Abstract: Photovoltaic agriculture has been effectively realized for the highly efficient and intensive utilization of clean energy and agricultural space resources. It is of great significance to deploy the photovoltaic power generation facilities and agricultural production activities on the same land space. The land use mode can also promote sustainable development for energy and food security. However, the layout of photovoltaic arrays can inevitably change the original distribution pattern of the solar and thermal environment on the surface, thus forming a significant spatial heterogeneity. The light intensity (shading effect) and duration can then be reduced in the area under the module. There is also a decrease in the spectral components (especially the proportion of photosynthetically active radiation, PAR) in the microclimate factors, such as temperature and humidity. The photothermal parameters can directly dominate the photosynthetic physiological links of the crops, such as the light energy capture efficiency, chlorophyll synthesis, stomatal conductance, and carbon assimilation rate (like Rubisco enzyme activity). These parameters can also interfere with the growth and development rhythm, biomass accumulation, and distribution patterns of the crops. Ultimately, there is a complex and significant impact on the yield potential and quality formation of the crops. Therefore, it is very necessary to explore the heterogeneity of the photothermal environment under photovoltaic arrays and its mechanism on the crop photosynthetic physiology and yield formation. The photovoltaic system can be optimized to screen the suitable crop varieties, and then formulate precise agronomic measures, in order to balance the synergistic benefits of the "photo-electricity-agriculture". This study aims to explore the influence of the different photovoltaic array structures on the internal light environment and the physiological response of the crops. A photovoltaic agricultural system planted with winter wheat was used as the experimental object. A field test was performed on the fixed and tracking brackets of the photovoltaic structures. The optical quantum sensors were used to continuously monitor the solar radiation intensity in the different planting areas (under photovoltaic panels and between plates) during the whole growth period. Simultaneously, the photosynthetic parameters were measured to determine the yield components of the wheat leaves. The test results show that there was significant spatial heterogeneity in the internal light environment of the photovoltaic system. The inter-plate lighting rate in the fixed bracket area reached 84.3%, which was significantly higher than that in the sub-plate area, 37.2% (P<0.05). However, there was no significant difference in the solar radiation intensity between the plates (56.6%) and the subplates (53.4%) in the tracking stent area. The shading effect led to a decrease of 58.7%-61.1% in the average yield of each treatment group, compared with the control. There were the same yield levels of the fixed (2 973.3 kg/hm2) and the traced stent area (3 198.2 kg/hm2). The density of the tracking bracket was similar to that of the fixed one. But the tracking bracket increased the power generation per unit area by 13.2%. The tracking scaffold significantly improved the energy yield efficiency for crop productivity. A promising potential can be expected to coordinate agriculture and photovoltaic cells. This finding can provide support to regulate the optical environment and decision-making on the agricultural photovoltaic projects.

     

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