Photosynthetically active radiation is a key parameter for determining crop yield. Separating photosynthetically active radiation into direct and diffuse components is significant to agrivoltaic systems. The varying shading conditions caused by the solar panels produce a higher contribution of diffuse irradiance reaching the crops. This study introduces a new separation model capable of accurately estimating the diffuse component from the global photosynthetically active radiation and conveniently retrievable meteorological parameters. The model modifies one of the highest-performing separation models for broadband irradiance, namely, the Yang2 model. Four new predictors are added: atmospheric optical thickness, vapor pressure deficit, aerosol optical depth, and surface albedo. The proposed model has been calibrated, tested, and validated at three sites in Sweden with latitudes above 58 °N, outperforming four other models in all examined locations, with R2 values greater than 0.90. The applicability of the developed model is demonstrated using data retrieved from Sweden's first agrivoltaic system. A variety of data availability cases representative of current and future agrivoltaic systems is tested. If on-site measurements of diffuse photosynthetically active radiation are not available, the model calibrated based on nearby stations can be a suitable first approximation, obtaining an R2 of 0.89. Utilizing predictor values derived from satellite data is an alternative method, but the spatial resolution must be considered cautiously as the R2 dropped to 0.73.

中文翻译：

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农业光伏系统建模中高纬度地区光合有效辐射分离模型

光合有效辐射是决定作物产量的关键参数。将光合有效辐射分为直接辐射和漫射辐射对于农业光伏系统具有重要意义。太阳能电池板造成的不同遮阳条件对到达农作物的漫射辐照度产生更大的影响。这项研究引入了一种新的分离模型，能够准确估计全球光合有效辐射的漫射分量以及方便检索的气象参数。该模型修改了宽带辐照度性能最高的分离模型之一，即 Yang2 模型。添加了四个新的预测因子：大气光学厚度、蒸气压差、气溶胶光学深度和表面反照率。所提出的模型已在瑞典纬度高于 58 °N 的三个地点进行了校准、测试和验证，在所有检查地点均优于其他四个模型，R2 值大于 0.90。使用从瑞典第一个农业光伏系统检索的数据证明了所开发模型的适用性。测试了代表当前和未来农业光伏系统的各种数据可用性案例。如果无法进行漫射光合有效辐射的现场测量，则基于附近站点校准的模型可以是合适的第一近似值，获得 0.89 的 R2。利用从卫星数据导出的预测值是另一种方法，但必须谨慎考虑空间分辨率，因为 R2 降至 0.73。