Optical performance and design optimization of V-trough concentrators for photovoltaic applications
Optical performance and design optimization of V-trough concentrators for photovoltaic applications
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DOI：
10.1016/j.solener.2011.06.001
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发表时间：
2011-09
期刊：
影响因子：
6.7
通讯作者：
R. Tang;Xinyue Liu
中科院分区：
文献类型：
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作者：
R. Tang;Xinyue Liu
在这项工作中，一个详细的数学程序来估计的基础上的V型槽聚光器，太阳能电池连接，开发的基础上的成像原理的平面镜，太阳几何和每月的水平辐射的可收集的辐射。该模型可以预测任何结构和安装参数的V形槽的光学性能，并优化这种聚光器的设计。计算结果表明，对于固定的东西向V型槽，（简而言之，EW-V槽）在给定几何聚光因子（Cg）和侧壁反射率（ρ）的情况下，年太阳能增益取决于其开口角、孔径倾斜角和场地气候条件，以及一组最佳的开口角度和孔径倾斜-通过对不同开角和倾斜角的迭代计算，得到了最大年太阳增益的开角。对于Cg=2，ρ=0.9的固定EW-V槽，以纬度作为准最佳倾斜角在全国范围内是合理的，方位角偏离正南15°，年可收集辐射减少不超过1%，垂直槽的几何轴线偏离水平线与V形槽扩展孔径的交点10°，年太阳增益的减少不超过1%。对于3个固定倾角、每年调整4次的EW-V型槽（3 T-EW-V型槽），在给定Cg和ρ的条件下，3 T-EW-V型槽在特定地点的年太阳增益近似为开口角的函数，通过对不同开口角的迭代计算，可以简单地估算出使年太阳增益最大的最佳开口角。3 T-EW-V型槽底的年太阳增益比固定型槽底的年太阳增益显著增加，尤其是在Cg较大的槽底，且月平均日太阳增益在一年中更为稳定。这意味着在一年中需要几次倾角调整，以使Cg>2的EW-V槽在一年中的所有日子里有效地将辐射集中到它们的耦合太阳能电池上。
In this work, a detailed mathematical procedure to estimate collectible radiation on the base of a V-trough concentrator, to which solar cells are attached, was developed based on the imaging principle of planar mirrors, solar geometry and monthly horizontal radiation. This model allows predicting the optical performance of V-troughs with any structural and installation parameters, and optimizing the design of such concentrator. Calculation results showed that for fixed east–west aligned V-troughs (EW-V troughs, in short) with given geometric concentration factor (Cg) and side wall reflectivity (ρ), the annual solar gain depended on its opening angle, tilt-angle of the aperture and climatic conditions in sites, and a set of optimal opening angle and aperture tilt-angle for maximizing annual solar gain could be obtained by iterative calculations for different opening angles and tilt-angles. It was also found that for fixed EW-V troughs with Cg=2 and ρ=0.9, taking the site latitude as quasi optimal tilt-angle was reasonable over all area of China, 15° deviation of azimuth angle from the due south would resulted in reduction of the annual collectible radiation less than 1%, and 10° deviation of the geometric axial line from the crossing line between the horizon and the extended aperture of V-troughs resulted in the reduction of annual solar gain less than 1%. For EW-V troughs with the tilt-angle of the aperture being yearly adjusted four times at three fixed tilt-angle (3T-EW-V troughs), the annual solar gain captured by 3T-EW-V troughs with given Cgand ρ in a specific site was approximately a function of the opening angle, and the optimal opening angle for maximizing annual solar gain could be simply estimated by iterative calculations for different opening angles. Compared with fixed EW-V troughs, the annual solar gain on the base of 3T-EW-V troughs increased significantly, especially for those with a large Cg, and the monthly average daily solar gain was more stable over a year. This implied that several tilt-angle adjustments in a year were required to make EW-V troughs with Cg>2 efficiently concentrate radiation onto their coupling solar cells in all days of a year.