An analysis of the dust deposition on solar photovoltaic modules

An improved numerical model to predict the operating temperature and efficiency of solar photovoltaic systems

Solar photovoltaic (PV) technology has a huge potential for producing renewable energy and reducing greenhouse gas emissions. An increase in the PV cell temperature in real operating conditions reduces the actual output of a solar PV system. A 1D transient multi-layered model, based on the fundamentals of the finite difference method, has been developed to predict the operating cell temperature. Since a PV system operates in stochastic wind conditions and is not subjected to any predefined thermal boundary condition, several expressions of convection coefficient have been scientifically analyzed to determine the most suitable expression. The novel calculation approach assumes explicit radiation terms and implicit convection terms to linearize the equations and get rid of any iterative process. Comparison with experimental results shows that the convection coefficient derived from boundary layer theory corresponding to uniform heat flux predicts the cell temperature with the best accuracy showing a mean error of only [Formula: see text] and [Formula: see text]. Splitting the heat source across different solar PV layers produces a maximum change of [Formula: see text] only and can be avoided due to the involved complexity. The study proposes a new piece-wise function for PV efficiency in terms of cell temperature and irradiation. This novel function predicts PV efficiency on a sunny and a cloudy day with [Formula: see text] and [Formula: see text] mean errors, respectively, which are considerably lower than errors obtained using other popular functions in the literature. The model helps in predicting actual output from a PV system more accurately which should enable taking more informed decisions regarding the location of installation, PV technology, and the need for a cooling method.

A review of dust accumulation on PV panels in the MENA and the Far East regions

This paper presents a comprehensive review regarding the published work related to the effect of dust on the performance of photovoltaic panels in the Middle East and North Africa region as well as the Far East region. The review thoroughly discusses the problem of dust accumulation on the surface of photovoltaic panels and the severity of the problem. Moreover, a survey of the most advanced cleaning techniques is presented, and their applicability is evaluated. There are plenty of techniques that have been used to remove the dust accumulated on the surface of PV panels, and these include manual and self-cleaning methods. However, it is concluded from the presented review that there is a strong need for developing new cleaning methods especially for the Middle East and North Africa region, which do not consume water and have low capital and operational costs with less human intervention, especially for hot, arid, and dusty regions.

Anti-Soiling Coatings for Enhancement of PV Panel Performance in Desert Environment: A Critical Review and Market Overview

Areas with abundant sunlight, such as the Middle East and North Africa (MENA), are optimal for photovoltaic (PV) power generation. However, the average power loss of photovoltaic modules caused by dust accumulation is extreme and may reach 1%/day, necessitating frequent cleaning which adds to the cost of operations and maintenance. One of the solutions to the problem of PV soiling is to develop anti-soil coatings, where hydrophilic or hydrophobic coatings with spectral characteristics suitable for PV applications are added to the outer layer of PV glass. However, the effectiveness of such coatings depends extensively on climatic conditions and geographical locations. Since coatings add to the cost of solar panels, it is imperative that they are first tested for suitability at the intended location and/or in similar weather conditions prior to their large-scale deployment. This critical review focuses on various anti-dust technologies employed to mitigate the PV soiling issue. The in-depth comparison of the various developed techniques and materials aims at providing a relevant input in adapting the right technology based on particles' accumulation mechanism, weather conditions, and geographical location. Though the mechanical cleaning process is the most used solution to date, development of thin film anti-dust coating could be a better alternative-when it is relevant-due to its abrasion-free capability, large deployment, economic viability, and durability. This review aims at serving as a reference in this topic, thereby paving the way to adapting efficient anti-dust coatings, especially in the MENA region and/or desert environment at large, where it is the most relevant.

Water droplet behavior in between hydrophilic and hydrophobic surfaces and dust mitigation

An innovative method is introduced for environmental dust mitigation from a hydrophobic surface by a sessile water droplet. The sessile water droplet is located between two parallel plates having hydrophilic (at the top) and hydrophobic (at the bottom) states. The water droplet is located at the top hydrophilic plate, and the effect of the plate spacing on dust mitigation rate is examined. The droplet behavior is analyzed for different plate spacings and various droplet sizes using a high-speed camera. The fluid and the particle motions are simulated inside the droplet while adopting the experimental conditions. The findings demonstrate that the sessile droplet can effectively mitigate dust. Reducing the plate spacing increases the droplet meniscus diameter and enhances the dust removal rate. The surface tension force on the hydrophilic surface remains greater than that of the pinning force on the dusty hydrophobic surface even though the Magdeburg and surface tension forces contribute to the droplet pinning force on the hydrophobic dusty surface. Flow current is developed in the droplet fluid during the squeezing period, which considerably enhances the dust removal rate from the hydrophobic surface. The cleaned area increases with the droplet volume and plate spacing. Stria patterns are observed on the circumference of the dust-removed area. The present study provides a detailed analysis of a new method of dust removal from surfaces for self-cleaning applications.

An innovative method is introduced for environmental dust mitigation from a hydrophobic surface by a sessile water droplet.

Optimization of Large-Scale Battery Storage Capacity in Conjunction with Photovoltaic Systems for Maximum Self-Sustainability

The photovoltaic array has gained popularity in the global electrical market. At the same time, battery storage, which is recently being placed by energy consumers alongside photovoltaics, continues to fall in price. Domestic and community loads may be combined utilizing central battery storage and shared solar power through an integrated grid or microgrid system. One of the main targets is maximum self-sustainability and independence of the microgrid system and implemented solution. This research study looks at the energy flows in a single household system that includes solar arrays and battery storage. The analysed household system is represented by a model which uses real load profiles from experimental measurements, local solar distribution, and onsite weather data. The results show that depending on the system configuration, two important parameters, self-consumption and self-sufficiency, can vary significantly. For a properly designed photovoltaic system, the energy self-consumption can be up to 90.19%, while self-sufficiency can be up to 82.55% for analysed cases. As an outcome, a large sample size with a variety of setups is recommended for a thorough examination of self-sustainability. Regional variations can worsen under different weather conditions, different photovoltaic and battery capacities, and different municipal rules.

Impact of wind on strength and deformation of solar photovoltaic modules

Maritime transport is one of the most important modes of transportation and plays an important role in facilitating world trade. In recent years, the maritime transport industry has been required to comply with "low carbon" policies. To meet the "low carbon shipping" policies, solar energy as a source of renewable energy has attracted more attention in the shipping industry. Photovoltaic solar panels, which to generate ships' electricity, are always vulnerable to wind damage because they are mounted on deck. At present, they do not provide comprehensive guidelines for reducing the impact of wind on photovoltaic structures. The present study contributes to the evaluation of the deformation and robustness of photovoltaic module under ocean wind load according to the standard of IEC 61215 using the computational fluid dynamics (CFD) method. The effect of wind on photovoltaic panels is analyzed for three speeds of 32 m per second (m/s), 42 m/s, and 50 m/s.

In Situ Tests of the Monitoring and Diagnostic System for Individual Photovoltaic Panels

The dynamic development of photovoltaic systems in the world and in Poland is mainly related to the drop in prices of installation components. Currently, electricity from photovoltaics is one of the cheapest renewable energy sources. The basis for effective energy generation is, first of all, failure-free operation of the photovoltaic system over a long period of operation, up to 30 years. The paper presents the results of a study of a low-cost distributed system for monitoring and diagnosis of photovoltaic installations (SmartPV), capable of assessing the operating parameters of individual photovoltaic panels. The devices were tested by connecting them to an existing photovoltaic installation, allowing the measurement of operational parameters of individual photovoltaic panels as well as operating conditions such as illuminance and panel surface temperature. The data were recorded on a server using wireless Wi-Fi transmission. Interesting data were collected during the tests, confirming the usefulness of the suggested device for monitoring the photovoltaic installations. Differences in performance of the photovoltaic panel depending on solar radiation and surface temperature were recorded. The temperature coefficient of power was determined, allowing for increased accuracy in the prediction of generated power. The correct recording in different situation, i.e., shading, sensor damage or weather anomalies, was verified. Based on the collected data, rules will be defined for an expert application which, in combination with SmartPV devices, will ensure a quick response to any malfunctions of the photovoltaic system, both related to failures and those resulting from natural degradation during operation.

Soiling Effect Mitigation Obtained by Applying Transparent Thin-Films on Solar Panels: Comparison of Different Types of Coatings

Dust accumulation on the front cover of solar panels is closely linked to location and orientation of photovoltaic (PV) installation. Its build-up depends on the module tilt angle, frequency of precipitation, humidity, wind strength and velocity, as well as grain size. Additionally, soil composition is determined by solar farm surroundings such as local factories, agricultural crops, and traffic. Over time, molecules of atmospheric dust agglomerate on top of each other and cause gradual reduction in generated energy. Manual cleaning techniques are required to restore working conditions of PV installation to their original conditions; however, they are time consuming and may lead to damage of the glass coverage. Therefore, implementing a different approach by utilizing self-cleaning and anti-dust coatings on front covers of module surfaces is thought of as a competitive manner of cleansing. Based on the varying properties of such thin-films, a division was made into hydrophobic, hydrophilic, and anti-dust coatings. In this article, the authors would like to present a comprehensive review of those types of transparent films. Moreover, a few hydrophobic coatings available on the Polish market were analyzed by applying them on glass tiles and covering them with three types of dust.

The Analysis of Working Parameters Decrease in Photovoltaic Modules as a Result of Dust Deposition

The aspect of dust accumulation on the surface of photovoltaic (PV) modules should be thoroughly understood in order to minimize possible obstacles affecting energy generation. Several elements affect the amount of pollutant gathered on the surface of a solar device, mainly its localization, which is irreversibly linked to factors such as annual rainfall, occasional snow coverage, or, in a dry climate, increased blow of dust during sandstorms and higher concentration of soil particles in desert areas. Other than weather conditions in the region, PV installation type also plays an important role as a more horizontal position is favorable for the accumulation of soil. The research carried out and presented in this paper was done for dust accumulated naturally on PV modules kept in outdoor conditions and dust artificially sieved onto the front glass cover of modules. The experiment performed by the authors, including artificially deposited dust, defined the linear relationship between surface dust density of different types of contaminants and efficiency decline up to 10% for two different PV modules. The additional field study carried out in external conditions for a coastal region in Northern Poland concluded that, after one year, exposition photovoltaic conversion efficiency can be over 10% lower, with a slight performance improvement for the autumn season characterized by heavy rainfall.

An investigation of the dust accumulation on photovoltaic panels

The particle deposition on the surface of solar photovoltaic panels deteriorates its performance as it obstructs the solar radiation reaching the solar cells. In addition to that, it may cause overheating of the panels, which further decreases the performance of the system. The dust deposition on the surfaces is a complex phenomenon which depends on a large number of different environmental and technical factors, such as location, weather parameters, pollution, tilt angle and surface roughness. Hence, it becomes crucial to investigate the key parameters which influence dust accumulation and their interrelations. In this study, the phenomenon of dust deposition was studied experimentally in the urban area at one of the most polluted cities of Europe, i.e. Kraków, Poland. Solar photovoltaic panels tilted at angles 15° and 35° were exposed to atmospheric conditions for the period of eighteen months from 6 May 2017 until 30 November 2018. Dust samples were collected from the panels for the exposure period which ranged from one day up to 11 days. It was observed that lower tilt angles promote dust accumulation on the surface and that in the absence of wind and rain, deposition of particles on the surface of panels follows the pattern of concentration of PM2.5 and PM10 in the atmosphere. Wind and rainfall usually promote the removal of dust particles from the surface. However, rainfall not always aids the cleaning of panels, and it was observed that low-intensity rain results in a very low rate of PMs in the air and in much higher than typical dust deposition on the panel surface. It also accelerates the cementing of already deposited dust. It was only rainfall whose intensity was at least 38 mm/h that was sufficient to remove dust particles from the panels.

Estimating economic and environmental benefits of urban trees in desert regions

Trees in urban areas have a significant impact on air quality and other environmental issues. Trees can affect the concentration of air pollutants that we breathe in by directly removing pollutants or avoiding emissions and secondary pollutant formation in the atmosphere. In addition, trees have other benefits including increasing property value, intercepting storm water runoff and saving energy needed for cooling of buildings in hot seasons. In this work, we estimate economic and environmental benefits of three tree species typical for desert regions such as Acacia tortilis, Ziziphus spina-christi and Phoenix dactylifera. The benefits varied by species with Acacia tortilis having the highest overall benefits, mostly because of its large leaf surface area and canopy shape. Tree benefits from carbon reduction reached up to US $14 billion annually. Mature trees tended to be more beneficial than smaller trees for improving environmental conditions. The location of trees had minimal impact on the overall economic value. This assessment provides urban planners, foresters, and developers in desert regions with the information needed to make informed decisions on the economic and environmental benefits of urban tree planting.

Impact of bird dropping deposition on solar photovoltaic module performance: a systematic study in Western Rajasthan

One of the most critical challenges is bird dropping deposition (soiling) on a glass surface of the photovoltaic (PV) module in an open environment of Western Rajasthan. This paper has been now exclusively emphasized to focus on effects of the bird dropping phenomenon on the performance of PV systems. The presented study includes the impact of the seasonal bird dropping effect on the reduction in energy yield with various tilt angle configurations. Considering this, the highest level of reduction in power loss was observed at the end of winter (March) and minimum during rainfall (August) every year. The sitting/walking tendency of birds with the plate inclination directly affects the PV output, which is demonstrated by optical study of glass samples (bird dropping patterns). Consequently, the studies of optical transmittance conclude the effect of dropping with different tilt regions I (β < 25°), II (25° ≤ β ≤ 60°), and III (60° ≤ β ≤ 90°), i.e., explained by bird movement onto the module surface. The result also showed that optimal inclination β (40°) has a smaller soiling effect in tilt region II (25-60°) correspondingly.

The field experiments and model of the natural dust deposition effects on photovoltaic module efficiency

The maximisation of the efficiency of the photovoltaic system is crucial in order to increase the competitiveness of this technology. Unfortunately, several environmental factors in addition to many alterable and unalterable factors can significantly influence the performance of the PV system. Some of the environmental factors that depend on the site have to do with dust, soiling and pollutants. In this study conducted in the city centre of Kraków, Poland, characterised by high pollution and low wind speed, the focus is on the evaluation of the degradation of efficiency of polycrystalline photovoltaic modules due to natural dust deposition. The experimental results that were obtained demonstrated that deposited dust-related efficiency loss gradually increased with the mass and that it follows the exponential. The maximum dust deposition density observed for rainless exposure periods of 1 week exceeds 300 mg/m² and the results in efficiency loss were about 2.1%. It was observed that efficiency loss is not only mass-dependent but that it also depends on the dust properties. The small positive effect of the tiny dust layer which slightly increases in surface roughness on the module performance was also observed. The results that were obtained enable the development of a reliable model for the degradation of the efficiency of the PV module caused by dust deposition. The novelty consists in the model, which is easy to apply and which is dependent on the dust mass, for low and moderate naturally deposited dust concentration (up to 1 and 5 g/m² and representative for many geographical regions) and which is applicable to the majority of cases met in an urban and non-urban polluted area can be used to evaluate the dust deposition-related derating factor (efficiency loss), which is very much sought after by the system designers, and tools used for computer modelling and system malfunction detection.

A review on the direct effect of particulate atmospheric pollution on materials and its mitigation for sustainable cities and societies

Particulate matter (PM) has gained significant attention due to the increasing concerns related to their effects on human health. Although several reviews have shed light on the effect of PM on human health, their critical adverse effect on material's structure and sustainability was almost neglected. The current study is an attempt to fill this gap related to PM impact on structural materials under the overall consideration of sustainability. More specifically, this review highlights the existing knowledge by providing an overview on PM classification, composition, and sources in different locations around the world. Then, it focuses on PM soiling of surfaces such as solar panels due to an increasing need to mitigate the impact of soiling on reducing photovoltaic (PV) power output and financial competitiveness in dusty regions. This topic is of critical importance for sustainable deployment of solar energy in arid and desert areas around the world to help in reducing their impact on overall climate change and life quality. In addition, this review summarizes climate change phenomena driven by the increase of PM concentration in air such as radiative forcing and acid rain deposition due to their impact on human health, visibility and biodiversity. To this end, this work highlights the role of process management, choice of fuel, the implementation of clean technologies and urban vegetation as some possible sustainable mitigation policies to control PM pollution in cities and urban regions. This research is designed to conduct a comprehensive narrative literature review which targets broad spectrum of readers and new researchers in the field. Moreover, it provides a critical analysis highlighting the need to fill main research gaps in this domain. The findings of this review paper show that PM pollution imposes severe adverse impacts on materials, structures and climate which directly affect the sustainability of urban cities. The advantages of this review include the value of the extensive works that elaborate on the negative impacts of PM atmospheric pollution towards high level of public awareness, management flexibility, stakeholder's involvements, and collaboration between academy, research, and industry to mitigate PM impact on materials and human welfare.