Reference solar irradiance spectra are needed to specify key parameters of solar technologies such as photovoltaic cell efficiency, in a comparable way. The IEC 60904-3 and ASTM G173 standards present such spectra for Direct Normal Irradiance (DNI) and Global Tilted Irradiance (GTI) on a 37° tilted sun-facing surface for one set of clear-sky conditions with an air mass of 1.5 and low aerosol content. The IEC/G173 standard spectra are the widely accepted references for these purposes. Hence, the authors support the future replacement of the outdated ISO 9845 spectra with the IEC spectra within the ongoing update of this ISO standard.

The use of a single reference spectrum per component of irradiance is important for clarity when comparing and rating solar devices such as PV cells. However, at some locations the average spectra can differ strongly from those defined in the IEC/G173 standards due to widely different atmospheric conditions and collector tilt angles. Therefore, additional subordinate standard spectra for other atmospheric conditions and tilt angles are of interest for a rough comparison of product performance under representative field conditions, in addition to using the main standard spectrum for product certification under standard test conditions. This simplifies the product selection for solar power systems when a fully-detailed performance analysis is not feasible (e.g. small installations). Also, the effort for a detailed yield analyses can be reduced by decreasing the number of initial product options.

After appropriate testing, this contribution suggests a number of additional spectra related to eight sets of atmospheric conditions and tilt angles that are currently considered within ASTM and ISO working groups. The additional spectra, called subordinate standard spectra, are motivated by significant spectral mismatches compared to the IEC/G173 spectra (up to 6.5%, for PV at 37° tilt and 10–15% for CPV). These mismatches correspond to potential accuracy improvements for a quick estimation of the average efficiency by applying the appropriate subordinate standard spectrum instead of the IEC/G173 spectra.

The applicability of these spectra for PV performance analyses is confirmed at five test sites, for which subordinate spectra could be intuitively selected based on the average atmospheric aerosol optical depth (AOD) and precipitable water vapor at those locations.

The development of subordinate standard spectra for DNI and concentrating solar power (CSP) and concentrating PV (CPV) is also considered. However, it is found that many more sets of atmospheric conditions would be required to allow the intuitive selection of DNI spectra for the five test sites, due in particular to the stronger effect of AOD on DNI compared to GTI.

The matrix of subordinate GTI spectra described in this paper are recommended to appear as an option in the annex of future standards, in addition to the obligatory use of the main spectrum from the ASTM G173 and IEC 60904 standards.

需要参考太阳辐照光谱以可比的方式指定太阳能技术的关键参数，例如光伏电池效率。IEC 60904-3和ASTM G173标准针对一组晴空条件，空气质量为1.5和1.5的一组晴空条件，给出了在37°朝阳表面上的直接法向辐照度（DNI）和全球倾斜辐照度（GTI）的光谱。气溶胶含量低。IEC / G173标准光谱是用于这些目的的公认参考。因此，作者支持在此ISO标准的不断更新中，将过时的ISO 9845光谱替换为IEC光谱。

在比较和定级太阳能电池（例如PV电池）并对其进行评级时，对于辐照度的每个分量使用单个参考光谱至关重要。但是，由于大气条件和收集器倾斜角度的差异很大，在某些位置，平均光谱可能与IEC / G173标准中定义的光谱有很大差异。因此，除了在标准测试条件下使用主要标准光谱进行产品认证外，还需要其他大气条件和倾斜角度的下级标准光谱，以便对代表性田间条件下的产品性能进行粗略比较。当无法进行详细的性能分析（例如小型安装）时，这简化了太阳能系统的产品选择。还，

经过适当的测试后，这一贡献表明与ASTM和ISO工作组目前正在考虑的八组大气条件和倾斜角有关的许多附加光谱。与IEC / G173光谱相比，其他光谱（称为从属标准光谱）是由显着的光谱失配引起的（对于倾斜37°的PV最高可达6.5％，对于CPV的最高可达10-15％）。这些不匹配对应于潜在的精度改进，可通过应用适当的从属标准光谱而不是IEC / G173光谱来快速估计平均效率。

这些光谱在光伏性能分析中的适用性在五个测试点得到证实，可以根据这些位置的平均大气气溶胶光学深度（AOD）和可沉淀的水蒸气直观地选择次级光谱。

还考虑了DNI和聚光太阳能（CSP）和聚光PV（CPV）的次级标准光谱的开发。但是，发现要想直观地选择五个测试点的DNI光谱，还需要更多套大气条件，特别是由于AOD对DNI的影响比GTI更强。

除了强制性使用ASTM G173和IEC 60904标准的主要光谱外，建议将本文所述的次要GTI光谱矩阵作为将来标准的附件中的一个选项出现。