Floating photovoltaics (FPV) is a relatively new concept for the PV community. The operating environment of FPV systems is different from that of conventional PV systems and offers the potential advantage of higher energy yield. Consequently, there is a rapid increase recently in both the installed and planned capacity of FPV systems worldwide. However, there exists a lack of knowledge and data about the performance stability of FPV systems. This paper presents, for the first time, a detailed analysis of the performance stability of FPV systems from one of the largest FPV testbeds worldwide, located on the Tengeh Reservoir in Singapore (tropical rainforest climate). The study is based on data gathered during the operation period of April 2017 to March 2020. Three commonly-used statistical methods are deployed to calculate performance loss rates (PLRs) — ordinary least squares (OLS), seasonal and trend decomposition using locally weighted scatterplot smoothing (STL) and year-on-year (YoY) methods. The mean PLRs of eight monitored FPV strings (all deploying crystalline silicon modules) based on OLS, STL and YoY are −0.7, −0.5 and −0.5%/year, respectively; the median annual PLRs (in the same order) are −0.6, −0.5 and −0.5%/year, respectively. These values are in line with the performance warranty from PV module manufacturers. Furthermore, a comparison is also made to two monitored PV strings (both deploying crystalline silicon modules) from a nearby rooftop reference system. Overall, there is no significant difference in the performance stability between the rooftop and the FPV installations in the testbed during the first three years of operation.

浮动光伏（FPV）是光伏社区相对较新的概念。FPV系统的操作环境不同于常规PV系统，并具有更高的能量产出潜力。因此，近来全球FPV系统的安装和计划容量都在迅速增加。但是，缺乏有关FPV系统性能稳定性的知识和数据。本文首次展示了位于新加坡腾格水库（热带雨林气候）的全球最大的FPV测试平台之一对FPV系统性能稳定性的详细分析。该研究基于2017年4月至2020年3月运营期间收集的数据。部署了三种常用的统计方法来计算性能损失率（PLR）-普通最小二乘（OLS），使用局部加权散点图平滑（STL）和同比（YoY）方法的季节和趋势分解。基于OLS，STL和YoY的八个受监视FPV串（均部署了晶体硅模块）的平均PLR分别为-0.7，-0.5和-0.5％/年；年度PLR的中位数（按相同顺序）分别为-0.6，-0.5和-0.5％/年。这些值符合光伏组件制造商的性能保证。此外，还对附近的屋顶参考系统中两个受监视的PV串（均部署了晶体硅模块）进行了比较。总体，