Overview of Factors Affecting Dust Deposition on Photovoltaic Cells and Cleaning Methods

Dust deposition on the surface of photovoltaic (PV) cells poses a significant challenge to their efficiency, especially in arid regions characterized by desert and semi-desert conditions. Despite the pronounced impact of dust accumulation, these regions offer optimal solar radiation and minimal cloud cover, making them ideal candidates for widespread PV cell deployment. Various surface cleaning methods exist, each employing distinct approaches. Choosing an appropriate cleaning method requires a comprehensive understanding of the mechanisms involved in both dust deposition on module surfaces and dust adhesion to PV cell surfaces. The mechanisms governing dust deposition and adhesion are complex and multifaceted, influenced by factors such as the nature and properties of the dust particles, environmental climatic conditions, characteristics of protective coatings, and the specific location of the PV installation. These factors exhibit regional variations, necessitating the implementation of diverse cleaning approaches tailored to the unique conditions of each location. The first part of this article explores the factors influencing dust deposition on PV cell surfaces, delving into the intricate interplay of environmental variables and particle characteristics. Subsequently, the second part addresses various cleaning methods, offering an analysis of their respective advantages and disadvantages. By comprehensively examining the factors influencing dust accumulation and evaluating the effectiveness of different cleaning strategies, this article aims to contribute valuable insights to the ongoing efforts to optimize the performance and longevity of photovoltaic systems in diverse geographical contexts.

Spatial and temporal gradients in the rate of dust deposition and aerosol optical thickness in southwestern Iran

The southwestern Iran is one of the regions that are most prone to dust events.The objective of this study is the analysis of the spatial and temporal distributions of dust deposition rate as a key factor for finding the relative impact of the dust.First,the monthly mean aerosol optical thickness(AOT)from Moderate Resolution Imaging Spectroradiometer(MODIS)was analyzed and compared with the dust amount variations from ground deposition rate(GDR),and the results were further used to investigate the spatial and temporal distributions of dust events in southwestern Iran for the period between 2014 and 2015.Moving air mass trajectories,using the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,were proven to be a discriminator of their local and regional origin.The results from GDR analysis produced a correlation coefficient between dust event history and deposition rates at dust magnitudes of>0.93 that is meaningful at the 95%confidence level.Furthermore,the deposition rates varied from 3 g/m2 per month in summer to 10 g/m2 per month in spring and gave insight into the transport direction of the dust.Within the same time series,AOT correspondences with MODIS on Terra in four aerosol thickness layers(clean,thin,thick,and strong thick)were shown in relation to each other.The deepest mixed layers were observed in spring and summer with a thickness of approximately 3500 m above ground level in the study area.Investigations of ground-based observations were correlated with the same variations for each aerosol thickness layer from MODIS images and they can be applied to discriminate layers of aeolian dust from layers of other aerosols.Together,dust distribution plots from AOT participated to enhance mass calculations and estimation deposition rates from the thick and strong thick aerosol thickness layers using the results from GDR.Despite all the advances of AOT,under certain circumstances,ground-based observations are better able to represent aerosol conditions over the study area,which were tested in southwestern Iran,even though the low number of observations is a commonly acknowledged drawback of GDR.

Influence of Dust Deposition on the Electrical Parameters of Silicon-Based Solar Panels Installed in Senegal (Dakar Region)

In recent years, photovoltaic (PV) modules are widely used in many applications around the world. However, this renewable energy is plagued by dust, airborne particles, humidity, and high ambient temperatures. This paper studies the effect of dust soiling on silicon-based photovoltaic panel performance in a mini-solar power plant located in Dakar (Senegal, 14°42'N latitude, 17°28'W longitude). Results of the current-voltage (I - V) characteristics of photovoltaic panels tested under real conditions. We modeled a silicon-based PV cell in a dusty environment as a stack of thin layers of dust, glass and silicon. The silicon layer is modeled as a P-N junction. The study performed under standard laboratory conditions with input data of irradiation at 1000 W/m2, cell temperature at 25°C and solar spectrum with Air Mass (AM) at 1.5 for the monocrystalline silicon PV cell (m-Si). The analysis with an ellipsometer of dust samples collected on photovoltaic panels allowed to obtain the refraction indices (real and imaginary) of these particles which will complete the input parameters of the model. Results show that for a photon flux arriving on dust layer of 70 μm (corresponding to dust deposit of 3.3 g/m2) deposited on silicon-based PV cells, short circuit current decreases from 54 mA (for a clean cell) to 26 mA. Also, conversion efficiency decreases by 50% compared to clean cell and the cell fill factor decreases by 76% - 50% compared to reference PV cell.

Electrostatic force of dust deposition originating from contact between particles and photovoltaic glass

Charged photovoltaic glass produces an electrostatic field.The electrostatic field exerts an electrostatic force on dust particles,thus making more dust particles deposited on the glass.In this paper,the contact electrification between the deposited dust particles and the photovoltaic glass is studied.Meanwhile,the surface charge density model of the photovoltaic glass and the electrostatic force of charged particles are analyzed.The results show that with the increasing of the particle impact speed and the inclination angle of the photovoltaic panel,the charges on particles increase to different degrees.Under a given condition,the electrostatic forces acting on the charged particles at different positions above the glass plate form a bell-shaped distribution at a macro level,and present a maximum value in the center of the plate.As the distance between the particle and the charged glass decreases,the electrostatic force exerted on the particle increases significantly and fluctuates greatly.However,its mean value is still higher than the force caused by gravity and the adhesion force,reported by some studies.Therefore,we suggest that photovoltaic glass panels used in the severe wind-sand environment should be made of an anti-static transparent material,which can lessen the dust particles accumulated on the panels.

Experimental Investigation of Dust Deposit within Ceramic Filter Medium during Filtration-Cleaning Cycles

The penetration and deposit of particles within the medium is thought to be one reason that the residual pressure drop of the rigid ceramic filter increase with cycle number.In this study,the change in the microstructure of a single layer ceramic filter candle during filtration-cleaning cycle was observed by scanning electron microscope(SEM) and the resistance property of the filter was monitored accordingly.The experimental results show that there exists a serious dust deposit within the filter medium,especially at the surface region.This should be responsible for the decrease of the filter permeability.The deposit law of dust in the filter medium during filtration-cleaning cycle was then studied by measuring the deposit depth,the deposit amount,the particles distribution within the medium,the size distribution of deposited particles,and so on.Particles migration and fine particles penetration were found to be the main reasons,for which dust deposit within the filter medium became aggravated with cycle number.Based on a differential form of Ergun equation,an expression for the pressure drop of a used ceramic filter was developed with a good agreement with experimental results.Then,the effect of dust deposit on the residual pressure drop was studied at the different face velocities and dust sizes.It was found that face velocity and dust size significantly influence dust deposit within filter medium,and then the operation performance of the filter.

Grain-size Characteristics of Sediment in Daniugou Peatland in Changbai Mountains,Northeast China:Implications for Atmospheric Dust Deposition

The grain-size distribution characteristics and grain-size parameters of sediment in two vertical sections of Daniugou peatland in the Changbai Mountains were systematically investigated.A comparative analysis of the sediment granularity using a discriminative function with Hongyuan peat,red clay,loess-paleosol,fluvial deposit as well as lacustrine deposit was also conducted.It turns out that the vertical section of Daniugou peat ash is primarily constituted by clay and silt particles,and the content of sand is relatively small.Grain-size frequency curves generally show a single-peak modality while a bimodal pattern is detected in the upper layer.The grain-size component and peak pattern of grain-size frequency curves also illustrate that peat ash materials were transported to the peatland by long-range aeolian dust during the deposition process,while there existed short-distance dust influence in peat deposition of the upper layer.Comparisons of grain-size parameters and the discriminative Y-value of Daniugou peat ash with those of typical aeolian sediments show close similarities,suggesting the possibility that atmospheric dust transport processes were involved in the accumulation of peat again.Moreover,the variations of grain-size distribution suggest the local environmental deterioration which is just the driving force of local dust elevation.Grain-size analysis of peatland sediment is demonstrated to be one effective method to extract information about regional and global environmental evolution,and more attention should be paid to current local ecological environment and to seeking a balance between economic development and environmental protection in Northeast China.

Zinc and Chromium Load in Road Dust, Suspended Particulate Matter and Foliar Dust Deposits of Anand City, Gujarat

Anand, the milk capital of India, is a developing city with increasing vehicles and developmental activities going on at a fast pace. This study attempts to investigate the zinc and chromium concentration in street dust, suspended particulate matter and in foliar dust deposits. Ten sampling locations were selected based on the traffic density on the roads and different anthropogenic activity. Sampling was carried out in the dry months of January to March 2011. The range of Zn and Cr was 16.82 - 108.29 ppm and 118 - 151.5 ppm in the street dust respectively. Zn concentration in Suspended particulate matter lies in the range of 12.41 to 86 ppm and Cr concentration between 75 to 130 ppm. The range of Cr in foliar deposited dust varied from 79.54 ppm to 31 ppm. Whereas, for Zn maximum concentration was in S10 which is 42.34 ppm and minimum was in site S9, 23.73 ppm. ANOVA single factor showed that at 0.05 level of significance site wise variation of zinc and chromium concentration in SPM, Street dust and foliar deposited dust was not significant signifying similar source of contamination. Which is further strengthened by the good positive correlation found between the Zn and Cr concentration of street dust, leaf deposited dust and SPM. The Contamination Factor in the sites where metal concentration was high was 1.24 in S10 and 1.06 in S5 for Zn. For chromium the value of CF was 1.77 in S10 and 1.67 in S5. These values indicate that street dust is moderately contaminated with respect to zinc and chromium.

A module based modeling framework for estimating lunar dust deposition due to human activities

Lunar dust is considered to be one of the top challenges for enabling humans to have extended stays on the moon.Human activities such as module landings and launches,walking,rover operation and construction activities will inevitably produce a significant amount of dust.Therefore,it is important to estimate the potential range and intensity of dust deposition caused by these activities to minimize dust accumulation over time and for maintenance planning and execution.A modular model that correlates the dust deposition distribution with initial mean dust particle velocity,its mean ejected angle and the total amount of ejected mass is developed for an elementary mechanical movement.This modular model is further employed to form a modeling framework to estimate dust deposition of a trajectory based activity of similar repeated movements such as the landing process of a lander,walking and rover operation.The model forms a unified modeling framework for different trajectory-based activities and is shown to predict consistent and physically meaningful ranges and intensities of dust deposition provided reliable data to calibrate the model parameters.

In-situ lunar dust deposition amount induced by lander landing in Chang’E-3 mission

China first in-situ lunar dust experiment is performed by a lunar dust detector in Chang’E-3 mission. The existed dust(less than 20 μm in diameter) properties, such as levitation, transportation and adhesion, are critical constraints for future lunar exploration program and even manned lunar exploration. Based on the problems discussed above, the in-situ lunar dust detector is originally designed to characterize dust deposition properties induced by lander landing as a function of environmental temperature, solar incident angle and orbit short circuit current on the northern Mare Imbrium, aiming to study lunar dust deposition properties induced by lander landing in depth. This paper begins with a brief of introduction of Chang’E-3 lunar dust detector design,followed by a series of experimental analysis of this instrument under different influencing factors, and concludes with lunar dust mass density deposition amount observed on the first lunar day is about 0.83 mg/cm^2, which is less than that observed in Apollo 11 mission because the landing site of Chang’E-3 has the youngest mare basalts comparing with previous Apollo and lunar landing sites. The young geologic environment is less weathered and thus it has thinner layer of lunar dust than Apollo missions’;hence, the amount of kicked-up lunar dust in Chang’E-3 mission is less than that in Apollo 11 mission.

Aeolian dust transportation and deposition by near-surface winds in arid and semiarid China

Dustfall collections were carried out in April and May 2001 and in March 2002 at six sites in northern China.Our results showed that the total deposition of dust fractions 【250 μm in diameter and the deposition of Fe both decreased exponentially with increasing distances from the source areas,and that the half-attenuation distance (HAD) for dust deposition was about 229 km in this re-gion.The HAD was closely related to the grain-size distribution of the dust,and the 15 to 20 μm fractions had the longest HAD.However,the fractions 【15 μm in diameter can be easily adsorbed to coarse particles and deposited after only short distances,and the HAD for the fractions 15 to 100 μm in diameter showed a power relationship with the grain-size distribution.The HAD for Fe deposition was 233 km,which was a little longer than that of total dust deposition,which suggests that the Fe content is higher in fine particles than in coarse particles,as previous studies have suggested.In addition,our analysis showed that under the control of current climatic conditions,the coarse fractions in dust derived from northwestern China cannot be transported over long distances,instead,it is transported primarily by near-surface winds (【3 km above the ground).The Fe in aeolian dust generated from arid and semiarid regions of China and deposited in the North Pacific region is usually transported by the upper westerlies.

Long range trans-Pacific transport and deposition of Asian dust aerosols

The deposition of Asian dust aerosols during their trans-Pacific transport might cause significant marine phytoplankton biomass increases. However, the knowledge of the trans-Pacific dust transport, deposition, and spatial distribution is still poor due to a lack of continuous and simultaneous observations in the Asian subcontinent, the north Pacific Ocean, and North America. The severe Asian dust storm during 6 to 9 April 2001 provided an opportunity to gain a better understanding of trans-Pacific dust transport and deposition, using a comprehensive set of observations from satellites, ground-based light detection and ranging, aircraft, and surface observation networks. The observations and model simulations outline the general pattern of dust transport, deposition, vertical profile, and spatial distribution. The following points were observed： （1） the surface dust concentrations decreased exponentially with the increasing dust transport distance from 80°E to 120°W along the transport pathway; （2） the altitude of the dust concentration peak increased with increasing transport distance in the north Pacific region; and （3） the spatial distribution of dust deposition mainly depended on the trans-Pacific transport route.

Research on Photovoltaic Performance Reduction due to Dust Deposition: Modelling and Experimental Approach

Photovoltaic(PV) power generation technology is the main renewable energy utilization technology. However, dust deposition severely affects the PV power generation efficiency and decreases the production capacity of PV power plants. In this study, the factors affecting PV technology were divided into the following three types: occlusion, corrosion, and temperature rise. A dust-collecting PV model considering dust deposition and rainfall scouring was established;a PV performance index was proposed. By conducting experiments with different dust mass densities, it was found that the short-circuit current(SCC), open-circuit voltage(OCV), and PV output power of PV decreased with the increase in dust mass density. In the initial stage of dust deposition, dust exhibited the greatest effect on the performance of PV. In the later stage of dust deposition, the effect of dust deposition became stable. The initial 10 g/m^2 dust decreased the PV output power by 34%. In addition, the conversion efficiency and fill factor(FF) decreased with the increase in dust mass density;both of them were exponential functions. When the dust mass density was low(less than 30 g/m^2), the dust mass density increased by 10 g/m^2, and the conversion efficiency decreased by an average of 3.4%. Finally, by conducting economic calculations, it was found that a PV power plant where dust has not removed for one year will cause 12% loss of power generation.

Estimation of the Total Dust Column and Dry Deposition Flux over the Yellow Sea,China Based on Shipboard Sun Photometer Measurements:Case Study

The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MKⅡ in a cloud-free and nonfrontal dust condition on 24 April 2006.The total dust column was calculated by using an integration method of the particle size distribution;the mean value was 1.42±0.30 g m 2.A linear correlation between the total dust column and the aerosol optical depth (AOD) with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study;the results were lower than these calculated by the integration method.A reasonable factor of 3.2 g m 2 was achieved by minimizing the standard deviation (SD) of the two methods.The two layers model,which includes the deposition processes of turbulent transfer,Brownian diffusion,impaction and gravitational settling over the sea's surface,was used to calculate the dry deposition flux;the mean value was 5.05±2.49 μg m 2 s 1.A correlation among the total dust column,dry deposition flux,AOD,and effective radius was discussed.The correlation between the total dust column and the AOD was better than that between the total dust column and the effective radius;however,the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.

Simulating Dry Deposition Fluxes of PM_(10) and Particulate Inorganic Nitrogen over the Eastern China Seas During a Severe Asian Dust Event Using WRF-Chem Model

A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.

Discowry of Cosmic Dust in Gold Deposits in Northwestern Sichuan and Its Significance

In recent years, a considerable amount of microscopic spherules have been found in concentrates recovered from some stratabound gold deposits occurring in Middle-Upper Triassic turbidite series in northwestern Sichuan. Study indicates that these spherules are cosmic dust. It is the first time that cosmic dust of extraterrestrial origin has been found in hydrothermal gold deposits in China.The spherules are steel-grey in colour and show metallic luster. Their grain size is commonly less than 100 μm. According to their composition, they belong to chromium-rich iron cosmic dust. The spherules have complex and diverse microscopic structures and textures, i.e. they show a very distinct Widmanstaten structure.The variation of cosmic dust content in gold deposits exhibits a positive correlation with the mineralization intensities and hydrothermal alteration. Such a relation indicates that the ore sub- stances may transport not only mechanically but also may chemically in hydrothermal solutions.

The Dust Comportment in the Latitudinal Band 10°North - 20°North in Africa: Emission and Deposition

The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed in the 10°North to 20°North latitudinal band (10 - 20 band) of Africa. The 10 - 20 band has a permanent dust presence. The AERONET data show AOD peaks exceeding 2 in Senegal and Niger (on an AOD scale). The statistical study reveals intra-annual relationships in deposition. In Senegal, a significant deposition is observed.

新疆阿尔泰山不同泥炭地记录的全新世大气粉尘信息及其影响因素

本文以中国西北阿尔泰山铁力沙汗和哈拉萨孜泥炭地为研究对象,结合AMS^(14)C年代框架,高分辨率测定两处泥炭地柱芯中的微量元素和常量元素,分析中国西北高山区泥炭记录的全新世大气粉尘历史沉降过程及其影响因素。研究发现:铁力沙汗和哈拉萨孜记录的全新世大气粉尘通量分别为22.74~76.92 g/(m^(2)·a)和18.60~198.38 g/(m^(2)·a)。与铁力沙汗相比,哈拉萨孜泥炭中矿物元素主要来源于大气沉降,表现为早全新世和早−中全新世时期粉尘通量较高,中全新世后粉尘通量较低,更能代表区域粉尘活动历史变化。阿尔泰地区泥炭记录的全新世粉尘通量高于季风区,且在中全新世后通量下降的特征,与季风区泥炭记录的高粉尘通量的结论相反。粉尘来源和气候环境是导致不同区域粉尘通量变化存在差异的主要原因。中国西北干旱区粉尘源区的湿度和温度通过影响植被覆盖状况,对区域大气沉降过程产生影响,但局地环境和冻土变化差异,也会导致区域内不同载体记录的大气粉尘信息存在明显差异。本研究对更全面更准确地认识区域大气环境变化过程及其主要影响因素,具有科学意义。

光伏组件表面积灰监控系统设计与实现

光伏组件表面积灰会影响组件的发电效率,降低光伏电站运行的经济性。为了能够监测光伏电站中组件表面的积灰状态,进而基于监测数据进行光伏电站清洗运维优化方法的研究,提出一种光伏电站组件表面积灰监控系统。该系统中,下位机采用STM32F407微处理器扩展ADS1256模数转换器采集与积灰相关的多种传感器信号,并通过无线传输模块将数据传给上位机监控软件。基于LabVIEW开发的上位机监控软件通过串口接收数据,处理并存储数据后,根据相应数据对光伏电站的清洗时间进行优化。经过实验测试,本系统能够准确地采集、传输、处理和储存数据,监测光伏电站组件表面的积灰状态并实现电站清洗时间的规划,对光伏电站清洗运维优化有重要意义。