The traditional point of view suggests photovoltaic systems to be installed at the optimum angles. However, various reasons require more flexible photovoltaic installations, especially for building-integrated photovoltaics. Some site-specific cases based on local irradiance data show that small deviations from the optimum will not cause big energy losses, while more theoretical insights on the flexible installation problem are required to achieve higher photovoltaic penetration. This paper tries to demonstrate that quite a large range of photovoltaic installation angles causes ignorable energy losses annually. Furthermore, this paper developed and validated a universal and convenient Loss Bound Equation to determine the 5% Loss Bound worldwide with high accuracy. The 5% Loss Bound is defined as a group of tilt and azimuth angle combinations where the plane-of-array energy losses are limited within 5% of the annual maximum plane-of-array irradiation. The universal Loss Bound Equation is independent of local irradiance data, which is totally different from conventional irradiance-based approaches and it is significantly faster and more convenient to use. The 5% Loss Bound will provide great flexibility for planning array spacing, decreasing dust deposition, sustainable retrofits to existing buildings, design for building-integrated photovoltaics, and so on.

传统观点认为光伏系统应以最佳角度安装。但是，由于各种原因，需要更灵活的光伏装置，尤其是对于建筑集成的光伏装置。基于局部辐照度数据的一些特定地点的案例显示，与最佳值的微小偏差不会导致大的能量损失，而需要更多的关于柔性安装问题的理论见解来实现更高的光伏穿透力。本文试图证明，很大范围的光伏安装角度每年都会导致可忽略的能源损失。此外，本文开发并验证了通用且方便的Loss Bound方程，可以高精度确定全球5％Loss Bound。5％损失边界定义为一组倾斜和方位角组合，其中阵列平面的能量损失限制在年度最大平面阵列辐射的5％以内。通用的“损失边界方程”与局部辐照度数据无关，这与常规的基于辐照度的方法完全不同，并且显着更快，更方便使用。5％的损耗界限将为规划阵列间距，减少灰尘沉积，对现有建筑物进行可持续改造，为建筑物集成的光伏发电进行设计等提供极大的灵活性。这与传统的基于辐照度的方法完全不同，并且使用起来明显更快，更方便。5％的损耗界限将为规划阵列间距，减少灰尘沉积，对现有建筑物进行可持续改造，为建筑物集成的光伏发电进行设计等提供极大的灵活性。这与传统的基于辐照度的方法完全不同，并且使用起来明显更快，更方便。5％的损耗界限将为规划阵列间距，减少灰尘沉积，对现有建筑物进行可持续改造，为建筑物集成的光伏发电进行设计等提供极大的灵活性。