Characterization of Soiling Bands on the Bottom Edges of PV Modules

Yong-Qin Cui,Jia-Huan Sun,Jian-Hua Xiao,Jin-Li Xiang

doi:10.3389/fenrg.2021.665411

Yong-Qin Cui, Jia-Huan Sun + Show 2 more

Open Access

https://doi.org/10.3389/fenrg.2021.665411

Copy DOI

Abstract

Soiling of photovoltaic (PV) modules, especially non-uniform soiling, can lead to PV power loss. For example, soiling bands at the bottom edge of framed modules are caused by the accumulation of water and dirt at a lower tilt angle. However, few studies have investigated this issue. In this study, industrial and commercial metal rooftop PV power stations in central and eastern China were investigated, with a focus in Xi’an and Kaifeng cities. The results show that (1) soiling bands were widespread, even in Guangzhou city, where annual rainfall is approximately 1,800 mm; (2) soiling bands were found during every month in Xi’an city, even from July to September when heavy rainfall occurs frequently; (3) three types of soiling bands were observed on modules (rectangular, transverse trapezoidal, and triangular), with double triangular, arch, and shallow U-shape types also being observed in landscape-oriented modules; (4) the mean relative difference of the maximum direct current due to soiling bands between one maximum power point tracking system and its control from June 19 to October 2, 2019 in Kaifeng city was approximately 4.7%.

Highlights

The accumulation of dust, dirt, and other contaminants on photovoltaic (PV) modules is an important environmental factor that reduces energy generation from PV power plants (Gostein et al, 2014; Klugmann-Radziemska, 2020), especially in arid and semi-arid areas (Kimber et al, 2006; Sayyah et al, 2014; Cordero et al, 2018; Dahlioui et al, 2019)
Previous research has focused on the effect of uniform soiling distributions on PV power stations installed at a high tilt angle, with few studies on the effect of non-uniform soiling distribution, especially at a lower tilt angle
Previous field investigations conducted by the authors in this study have shown that modules in most industrial and commercial metal rooftop PV power stations with a lower tilt angle are installed in a portrait configuration, with few of them being installed in a landscape configuration at the central and eastern parts of China

Summary

INTRODUCTION

The accumulation of dust, dirt, and other contaminants on photovoltaic (PV) modules is an important environmental factor that reduces energy generation from PV power plants (Gostein et al, 2014; Klugmann-Radziemska, 2020), especially in arid and semi-arid areas (Kimber et al, 2006; Sayyah et al, 2014; Cordero et al, 2018; Dahlioui et al, 2019). Previous field investigations conducted by the authors in this study have shown that modules in most industrial and commercial metal rooftop PV power stations with a lower tilt angle are installed in a portrait configuration, with few of them being installed in a landscape configuration at the central and eastern parts of China. After cleaning the soiling bands, a hazy appearance of the glass corresponding to the location of soiling bands was observed at the lower edge of the PV modules during a few months after installation at Xi’an, which is not observed on the modules covered by partial shading This phenomenon was examined in Sánchez-Friera et al (2011) and is thought to be caused due to sedimentation of rainwater and an ion exchange between alkalis in the glass and H + ions in the water (Lombardo et al, 2005; Manganiello et al, 2015). Compared to the non-soiling areas of PV modules, the stagnant water corresponding to the location of the soiling bands has a longer invasion time due to the seal between the glass and the metal frame; this water can damage the seal and eventually reduce the service life of PV modules (John, 2015; Manganiello et al, 2015)

CONCLUSION

Findings

DATA AVAILABILITY STATEMENT