Estimating spectral plane-of-array (POA) solar irradiance on inclined surfaces is an important step in the design and performance evaluation of both photovoltaic and concentrated solar plants. This work introduces a fast, line-by-line spectral, Monte Carlo (MC) radiative transfer model approach to simulate anisotropic distributions of shortwave radiation through the atmosphere as photon bundles impinge on inclined surfaces. This fast Monte Carlo approach reproduces the angular distribution of solar irradiance without the undesirable effects of spatial discretization and thus computes detailed POA irradiance values on surfaces at any orientation and also when surfaces are subjected to the anisotropic ground and atmospheric scattering. Polarization effects are also easily incorporated into this approach that can be considered as direct numerical simulation of the physics involved. Here, we compare our Monte Carlo radiative transfer model with the most widely used empirical transposition model, Perez4, under various conditions. The results show that the Perez4 model reproduces the more detailed Monte Carlo simulations with less than 10% deviation under clear skies for all relevant surface tilt and azimuth angles. When optically thin clouds are present, observed deviations are larger, especially when the receiving surface is strongly tilted. Deviations are also observed for large azimuth angle differences between the receiving surface and the solar position. When optically thick clouds are present, the two models agree within 15% deviation for nearly all surface orientation and tilt angles. The overall deviations are smaller when compared with cases for optically thin clouds. The Perez4 model performs very well (∼6.0% deviation) in comparison with the detailed MC simulations for all cases, thus validating its widespread use for practical solar applications. When detailed atmospheric profiles and cloud optical properties are available, the proposed fast Monte Carlo radiative model reproduces accurate spectral and angular POA irradiance levels for various atmospheric and cloud cover conditions, surface orientations, and different surface and ground properties.

中文翻译：

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倾斜表面上的光谱太阳辐照度：快速蒙特卡罗方法

估计倾斜表面上的光谱阵列平面 (POA) 太阳辐照度是光伏和聚光太阳能发电厂设计和性能评估的重要步骤。这项工作引入了一种快速的逐行光谱蒙特卡罗 (MC) 辐射传递模型方法，以模拟光子束撞击倾斜表面时穿过大气的短波辐射的各向异性分布。这种快速的蒙特卡罗方法再现了太阳辐照度的角度分布，而没有空间离散化的不良影响，因此可以计算任何方向的表面上的详细 POA 辐照度值，以及当表面受到各向异性地面和大气散射时。偏振效应也很容易结合到这种方法中，可以将其视为所涉及物理的直接数值模拟。在这里，我们将我们的 Monte Carlo 辐射传输模型与最广泛使用的经验转置模型 Perez4 在各种条件下进行比较。结果表明，Perez4 模型再现了更详细的蒙特卡罗模拟，在晴朗的天空下，所有相关表面倾斜角和方位角的偏差小于 10%。当存在光学薄云时，观测到的偏差更大，尤其是当接收面强烈倾斜时。还观察到接收表面和太阳位置之间的大方位角差异的偏差。当存在光学厚云时，对于几乎所有的表面方向和倾斜角，这两种模型的偏差都在 15% 以内。与光学薄云的情况相比，总体偏差较小。与所有情况下的详细 MC 模拟相比，Perez4 模型表现非常好（~6.0% 偏差），从而验证了其在实际太阳能应用中的广泛使用。当可以获得详细的大气剖面和云光学特性时，所提出的快速蒙特卡罗辐射模型可以为各种大气和云覆盖条件、表面方向以及不同的表面和地面特性再现准确的光谱和角度 POA 辐照度水平。0% 偏差）与所有情况下的详细 MC 模拟相比，从而验证了其在实际太阳能应用中的广泛使用。当可以获得详细的大气剖面和云光学特性时，所提出的快速蒙特卡罗辐射模型可以为各种大气和云覆盖条件、表面方向以及不同的表面和地面特性再现准确的光谱和角度 POA 辐照度水平。0% 偏差）与所有情况下的详细 MC 模拟相比，从而验证了其在实际太阳能应用中的广泛使用。当可以获得详细的大气剖面和云光学特性时，所提出的快速蒙特卡罗辐射模型可以为各种大气和云覆盖条件、表面方向以及不同的表面和地面特性再现准确的光谱和角度 POA 辐照度水平。