The document discusses an automated cleaning system for removing dust from solar photovoltaic (PV) modules. Dust accumulation reduces light transmission and PV performance. The system uses a combination of mechanical cleaning methods like water jets, air jets, and module vibration on an 8 kW pilot-scale PV testbed in Saudi Arabia. Preliminary results found that water jets were most effective at increasing array power output by over 27% by removing sand, while air jets and vibration were less effective. The testbed allows testing different cleaning combinations and solutions to minimize water and energy use for cleaning large-scale PV arrays.
1. This document summarizes the environmental impact assessment conducted for the Jaipur Metro Rail Project in Jaipur, India.
2. Key aspects of the project include the construction of an underground metro system 12067km in length to help address the inadequate public transportation infrastructure in the growing city of over 3 million people.
3. The EIA process included collecting environmental baseline data, identifying potential impacts such as vibration, noise, waste generation during construction, and developing mitigation measures to minimize impacts and ensure compliance with relevant regulations.
The document describes models developed to predict soiling-caused photovoltaic (PV) power output degradation in Doha, Qatar based on environmental variables. Field data on PV performance and dust concentration, wind speed, and relative humidity were collected. A linear model and a semi-physical model were developed to correlate daily changes in PV performance (∆CI) with the daily average environmental conditions. The semi-physical model, which considers dust deposition and resuspension processes, predicted daily ∆CI slightly more accurately than the linear model based on R-squared values. However, both models performed roughly the same in predicting ∆CI over longer periods. The results suggest it is possible to use the models to estimate PV
EIA an introduction - Case study wrt Coastal development & AquacultureKANTHARAJAN GANESAN
This document summarizes an environmental impact assessment for the Mumbai Coastal Road Project. It describes the objectives of the EIA study as establishing the baseline environmental conditions, identifying elements that could be affected, predicting impacts, and developing mitigation measures. The report structure includes chapters on project description, alternatives analysis, environmental description, anticipated impacts and mitigation measures, and an environmental management plan. The coastal road project aims to address traffic issues in the dense city of Mumbai by constructing a 29.2 km road along the western coast, and the EIA aims to assess the project's environmental impacts and ensure sustainable development.
ENVIRONMENTAL IMPACT ASSESSMENT FOR ANDHERI (E)- DAHISAR (E) CORRIDOR OF MUMB...Mayur Rahangdale
The document provides an environmental impact assessment for the proposed Andheri (E)- Dahisar (E) corridor of the Mumbai Metro. Key details include:
- The 16.475km elevated metro line will have 14 stations and be fully elevated along the Western Express Highway.
- Baseline environmental data was collected on land, water, climate, air quality, noise levels, ecology and biodiversity, and socio-economic factors.
- During construction, impacts like increased dust and noise, traffic diversions, and tree removal will be mitigated. Operational impacts like noise and waste generation at stations will also be addressed.
- Overall, the metro is expected to provide environmental benefits from reduced
ENVIRONMENTAL IMPACT ASSESSMENT ON NEW ANDHRAPRADESH CAPITAL AREA (THULLURU)mandava geethabhargava
The document discusses the proposed construction of a new capital city for Andhra Pradesh in Thullur, Guntur district. It outlines the environmental impacts that may occur during construction, including increased air and noise pollution, impacts on water resources and land use. It also notes the social benefits of increased employment but potential issues around disrupting agriculture and existing residents. The Capital Region Development Authority is responsible for resettlement and rehabilitation of those affected, and measures must be taken to address environmental impacts and compensate residents before construction begins.
This document presents an environmental impact assessment report for the proposed construction of a 660 MW coal-fired power plant in Pakistan. The report was prepared by Nippon Koei Co., Ltd, Mitsui Consultants Co., Ltd., and Hagler Bailly Pakistan (Pvt.) Ltd. It describes the project location, outlines, legal framework, existing environment, potential impacts of construction and operation, and proposed mitigation measures. Key impacts addressed include air emissions, water usage and discharge, noise, waste generation, and socioeconomic effects. The report was prepared to comply with Pakistan's Sindh Environmental Protection Act 2014.
This document provides an executive summary of the proposed Central Secretariat-Badarpur Metro Corridor project in Delhi, India. It discusses the project description including the 20.16km alignment and 16 stations. It also summarizes the environmental baseline data collection, potential negative impacts during construction and operation such as loss of trees and risk of accidents, and proposed mitigation measures. Positive impacts include reduced traffic, fuel consumption, and air pollution. An environmental management plan is outlined to minimize impacts through training, monitoring of air, noise, and vibration, and implementation of measures for soil disposal, resettlement, and health and safety.
Environmental Impact Assessment of Sentosa Integrated ResortNovember Tan
An assignment for a class on Environmental Management and Assessment, we are asked to conduct an Environmental Impact Assessment on the reclamation on Sentosa island for the construction of a integrated resort.
It is important to note that this is in many ways a hypothetical EIA. There were assumptions made and we did NOT do any baseline surveys or studies. Information were all taken from other sources and projected for this site.
1. This document summarizes the environmental impact assessment conducted for the Jaipur Metro Rail Project in Jaipur, India.
2. Key aspects of the project include the construction of an underground metro system 12067km in length to help address the inadequate public transportation infrastructure in the growing city of over 3 million people.
3. The EIA process included collecting environmental baseline data, identifying potential impacts such as vibration, noise, waste generation during construction, and developing mitigation measures to minimize impacts and ensure compliance with relevant regulations.
The document describes models developed to predict soiling-caused photovoltaic (PV) power output degradation in Doha, Qatar based on environmental variables. Field data on PV performance and dust concentration, wind speed, and relative humidity were collected. A linear model and a semi-physical model were developed to correlate daily changes in PV performance (∆CI) with the daily average environmental conditions. The semi-physical model, which considers dust deposition and resuspension processes, predicted daily ∆CI slightly more accurately than the linear model based on R-squared values. However, both models performed roughly the same in predicting ∆CI over longer periods. The results suggest it is possible to use the models to estimate PV
EIA an introduction - Case study wrt Coastal development & AquacultureKANTHARAJAN GANESAN
This document summarizes an environmental impact assessment for the Mumbai Coastal Road Project. It describes the objectives of the EIA study as establishing the baseline environmental conditions, identifying elements that could be affected, predicting impacts, and developing mitigation measures. The report structure includes chapters on project description, alternatives analysis, environmental description, anticipated impacts and mitigation measures, and an environmental management plan. The coastal road project aims to address traffic issues in the dense city of Mumbai by constructing a 29.2 km road along the western coast, and the EIA aims to assess the project's environmental impacts and ensure sustainable development.
ENVIRONMENTAL IMPACT ASSESSMENT FOR ANDHERI (E)- DAHISAR (E) CORRIDOR OF MUMB...Mayur Rahangdale
The document provides an environmental impact assessment for the proposed Andheri (E)- Dahisar (E) corridor of the Mumbai Metro. Key details include:
- The 16.475km elevated metro line will have 14 stations and be fully elevated along the Western Express Highway.
- Baseline environmental data was collected on land, water, climate, air quality, noise levels, ecology and biodiversity, and socio-economic factors.
- During construction, impacts like increased dust and noise, traffic diversions, and tree removal will be mitigated. Operational impacts like noise and waste generation at stations will also be addressed.
- Overall, the metro is expected to provide environmental benefits from reduced
ENVIRONMENTAL IMPACT ASSESSMENT ON NEW ANDHRAPRADESH CAPITAL AREA (THULLURU)mandava geethabhargava
The document discusses the proposed construction of a new capital city for Andhra Pradesh in Thullur, Guntur district. It outlines the environmental impacts that may occur during construction, including increased air and noise pollution, impacts on water resources and land use. It also notes the social benefits of increased employment but potential issues around disrupting agriculture and existing residents. The Capital Region Development Authority is responsible for resettlement and rehabilitation of those affected, and measures must be taken to address environmental impacts and compensate residents before construction begins.
This document presents an environmental impact assessment report for the proposed construction of a 660 MW coal-fired power plant in Pakistan. The report was prepared by Nippon Koei Co., Ltd, Mitsui Consultants Co., Ltd., and Hagler Bailly Pakistan (Pvt.) Ltd. It describes the project location, outlines, legal framework, existing environment, potential impacts of construction and operation, and proposed mitigation measures. Key impacts addressed include air emissions, water usage and discharge, noise, waste generation, and socioeconomic effects. The report was prepared to comply with Pakistan's Sindh Environmental Protection Act 2014.
This document provides an executive summary of the proposed Central Secretariat-Badarpur Metro Corridor project in Delhi, India. It discusses the project description including the 20.16km alignment and 16 stations. It also summarizes the environmental baseline data collection, potential negative impacts during construction and operation such as loss of trees and risk of accidents, and proposed mitigation measures. Positive impacts include reduced traffic, fuel consumption, and air pollution. An environmental management plan is outlined to minimize impacts through training, monitoring of air, noise, and vibration, and implementation of measures for soil disposal, resettlement, and health and safety.
Environmental Impact Assessment of Sentosa Integrated ResortNovember Tan
An assignment for a class on Environmental Management and Assessment, we are asked to conduct an Environmental Impact Assessment on the reclamation on Sentosa island for the construction of a integrated resort.
It is important to note that this is in many ways a hypothetical EIA. There were assumptions made and we did NOT do any baseline surveys or studies. Information were all taken from other sources and projected for this site.
The present research shows the effect of dust accumulation on the surface of photovoltaic (PV) modules, which cause losses in their output power. We got 28% of losses in output power at Madinah city during 60 days of dust accumulation. Two ways were used to study the effect of dust on the PV modules of type monocrystalline silicon: the quantitative and the qualitative approaches respectively. A model based on dust density is used to determine the losses of output PV power. We propose to add an important parameter noted dust accumulation coefficient (%/mg.cm-2), in data sheet of PV modules manufacturer. In addition, an intelligent cleaning system is proposed, using the notion of dust density, to start cleaning when an admissible value of power losses is reached. This process allows minimizing the effect of dust.
This document reviews the effect of environmental factors like dust, temperature, and wind on photovoltaic module performance. Dust deposition reduces light transmission and module output, and high temperatures also decrease efficiency. Wind can help remove dust but also spread it; higher wind speeds generally result in lower module temperatures through increased cooling. The document examines past research on these impacts and promising strategies for mitigating dust accumulation, like electrostatic cleaning and surface treatments.
Experimental study of the impact of dust on azimuth tracking solar PV in Shar...IJECEIAES
Dust is one of the significant constraints in utilizing solar photovoltaic systems under harsh weather conditions in the desert regions due to creating a shadow that blocks solar irradiance from reaching solar cells and consequently, significantly reducing their efficiency. In this research, experimental study was performed to comprehend the nature of dust particles and their impact on the electrical power output that is generated from azimuth tracking solar PV modules under Sharjah environmental conditions in winter season. According to laboratory experiments, the power losses are linearly related to the dust accumulated density on the surface of the solar panel with a slope of 1.27% per g/m2. The conducted Outdoor studies revealed that the absolute reduction in output power increased by 8.46% after 41 continuous days with one low-intensity rainy day. The linear relationship obtained from indoor experiments was applied later to estimate the dust deposited density on the outdoor setup. The results showed that a regular cleaning process every two weeks is recommended to maintain the performance and to avoid the soiling loss. This work will help engineers in the solar PV plants to forecast the dust impact and figure out the regularity of the cleaning process in case of single axis tracking systems.
This document reviews various methods for cleaning solar photovoltaic panels to remove dust accumulation and improve efficiency. It discusses electrostatic cleaning systems that use electric fields to remove charged and uncharged dust particles. It also describes mechanical cleaning methods using wipers, brushes and vibrations driven by motors or piezoelectric transducers. Additionally, the document outlines microcontroller-based automatic cleaning robots and self-cleaning techniques using superhydrophobic coatings and nanoscale structures to prevent dust adhesion. Cleaning is important as dust deposition can reduce panel output by over 80% without maintenance.
This study examines the impact of four environmental factors - dust accumulation, water droplets, bird droppings, and partial shading conditions - on photovoltaic (PV) system performance. The results show that dust accumulation, shading, and bird fouling significantly reduce PV current, voltage, and harvested energy. Shading had the strongest negative effect, with power reduction of 33.7-92.6% depending on the shaded area. However, water droplets decreased PV panel temperature and slightly increased power output. Dust reduced power by 8.8% and efficiency by 11.86%. Bird fouling reduced performance by around 7.4%. The study provides quantitative analysis of how each factor individually affects key PV parameters and overall system
This study examines the impact of four environmental factors - dust accumulation, water droplets, bird droppings, and partial shading conditions - on photovoltaic (PV) system performance. The results show that dust accumulation, shading, and bird fouling significantly reduce PV current, voltage, and harvested energy. Shading had the strongest negative effect, with power reduction of 33.7-92.6% depending on the shaded area. However, water droplets decreased PV panel temperature and slightly increased power output. Dust reduced power by 8.8% and efficiency by 11.86%. Bird fouling reduced performance by around 7.4%. The study provides quantitative analysis of how each factor individually affects key PV parameters and overall system
Effect of pollution and dust on PV performanceIJCMESJOURNAL
This document summarizes an experimental study that evaluated the effect of three Iraqi construction materials (cement, plaster, and borax) on the performance of photovoltaic (PV) cells. The materials were applied in weights from 2 to 10 grams to PV cell samples. Plaster was found to have the greatest negative impact on current, power, and efficiency of the cells, reducing efficiency by up to 25.8% compared to clean cells. Borax had the smallest effect on current and caused the lowest degradation to PV cell performance. The results indicate the importance of keeping PV surfaces clean to maximize their economic benefits.
Case Study of Solar Power Plant Generation And Their Factors AffectingIRJET Journal
This document discusses factors affecting the performance of solar power plants. It begins by introducing solar energy as a renewable and sustainable energy source. It then discusses how environmental conditions like dust can impact the performance of photovoltaic systems, reducing power output. Various dust removal and panel coating techniques are examined from previous studies. Implementation costs for a 1MW ground-mounted solar plant are estimated to be around INR 4-5 crores. Expected power generation from such a plant in Tamil Nadu is around 4.5kW per kW of panels installed. The return on investment for a 1MW plant is estimated to be around 8.5 years. Proper site selection is also highlighted as an important factor influencing generation and material performance.
The document summarizes a study that measured photovoltaic (PV) performance, ambient dust levels, and weather conditions in Doha, Qatar from June to December 2014. Three PV arrays were monitored - one cleaned every week, one every two months, and one every six months. A "cleanness index" showed the arrays cleaned every six months lost on average 0.0042 of performance per day, while the two-month cleaned arrays lost 0.0045 per day. Daily changes in cleanness index were negatively correlated with dust levels and humidity but positively correlated with wind speed. A regression model related cleanness index changes to dust, wind, and humidity and showed dust deposition significantly reduced PV power generation
INFLUENCE OF SITE AND SYSTEM PARAMETERS ON THE PERFORMANCE OF ROOF-TOP GRID-C...IRJET Journal
This document analyzes the influence of site and system parameters on the performance of a 49.92 kW rooftop solar PV system in Belfast, Northern Ireland over five years. The researchers examined how ambient temperature, relative humidity, solar irradiation, wind speed, and air pressure (site parameters) as well as inverter efficiency, system performance ratio, and other metrics (system parameters) affected the system's output. Their results showed that higher temperatures, humidity, and solar irradiation decreased performance while higher wind speed increased it. Higher air pressure also increased solar irradiation and power output. The goal was to better understand how environmental conditions and system design impact the real-world efficiency of solar energy generation.
IRJET- Solar Panel Cleaning System with Inbuilt Power SupplyIRJET Journal
This document presents the design of an automated self-cleaning solar panel system with an inbuilt power supply. Dust and other debris accumulation on solar panels can reduce their efficiency by 5-30%. The designed system detects shading of solar cells using an Arduino controller and activates brush motors to clean the panels. It can clean 3 panel arrays in a row over 5 minutes. The cleaning mechanism is powered by a battery that is recharged by the solar panels when not in use. Future improvements discussed include drone-based cleaning and high voltage or ultrasonic cleaning methods.
Design and Development of a Dry-Cleaning System for Photovoltaic PanelsIRJET Journal
This document describes the design and development of a dry-cleaning system for photovoltaic panels. Dust accumulation on solar panels can reduce power production by up to 42%. The researchers designed an automatic cleaning robot that uses an Arduino microcontroller to travel along photovoltaic panels and remove dust using brushes. Testing showed the robot successfully cleaned dust off the panels and improved power output, demonstrating the viability of such a system for maintaining solar panel effectiveness over time. The document discusses various cleaning mechanisms proposed in other studies and outlines the design, methodology, results and conclusions of the researchers' dry-cleaning robot system.
effect of environmental variables on photovoltaic performance based on experi...IJCMESJOURNAL
This paper investigated the effect of environment variables on Photovoltaic PV performance. It is surely understood that local climate can dramatically affect the power generation from a PV system. The most obvious components are the solar radiation hitting the panels, air temperature, humidity and wind speed. The local climatic conditions and precipitation influence the extent to which the panels get to be dusty or polluted, which affects the electrical power generation. The high air temperature caused a reduction in the PV panel output power rated from 1.85 to 20.22%, as well as, increased relative humidity where the largest decline recorded was 32.24%. The wind has a cooling effect on the PV panel that limits the power reduction due to increased solar radiation or panel back temperature. Besides, the wind blows away the accumulated dust that enhances the resulted PV panel power.
In previous experiments, dust accumulation for the solar panels has been investigated for a long period of time which is approximately one year [1]. The experiments have been done in different countries which have climate conditions of the dusty weather. Those countries are Iraq, Egypt and UAE. The solar panels were never cleaned, firstly for one month, secondly for two months and so on. The results were there was a decreasing in the transmittance of the solar panels, which is emphasize the effect of accumulated dust, even though the changing in the tilt angel which is in conjunction with the dust deposition on the panels. A well designed auto cleaning system to clean the solar panels will be added to the panels to keep the transmittance of the solar planes fixed approximately and to reduce the cost- of periodic cleaning
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The document reviews various solar distillation technologies for desalination. It discusses different types of solar concentrators and collectors that can be used to heat saline water and produce fresh water through distillation. Several studies that have tested different solar distillation designs and configurations are summarized. These include designs using parabolic concentrators, double pass solar air heaters, humidification-dehumidification processes, and systems combining multiple technologies. The document indicates that solar distillation is a promising technology for desalination using renewable energy but further improvements are needed to increase efficiency and competitiveness compared to conventional thermal desalination methods.
The aim of this research is to utilize the new control algorithm of the sun tracker and the developed computer capabilities to improve the efficiency of tracking. The new tracking method installed on new innovative approach of water distillation taking advantage of high possible concentration of parabolic trough collector to reach a new level of daily harvest per square meter. Water distillation yield is predicted to score high percentage output of distillate due to the high temperature average about 40 degrees as maximum and 30 degrees as minimum. Also the high sunny hours about 9-12 hours per day. Mechanical system will be designed and tested for high ability to withstand the extra loading also some imperfections are forecasted. The present study may found more reliable and trusting techniques in tracking and water distillation. Saline water distillation as predicted will score a noticeable level because of the use of parabolic collector and promoted the efficiency. Keeping good temperature difference between vapor and condensation surface will increase the output and reduce the capacity of temperature. The mechanical design must be convenient to Sultanate Oman climate conditions and have to running, smoothly and safe.
Cloud seeding involves introducing substances like silver iodide or dry ice into clouds to modify their development and increase precipitation. It is used to address water stress as populations and industries grow. India is vulnerable to rainfall variations due to its infrastructure and agriculture. Cloud seeding works by providing particles for cloud droplets and ice crystals to form on. There are different types of cloud seeding that introduce particles in different ways. Monitoring equipment like radar and networks are needed to analyze seeded clouds. Studies in India have used software to compare parameters of seeded and unseeded clouds to evaluate cloud seeding effectiveness. Both benefits and disadvantages exist regarding its ability to augment water resources versus costs and uncertainties.
The document proposes a research plan called the Global Albedo Enhancement Project (GAEP) to address global warming. The plan involves covering desert areas with white plastic film to increase albedo and reduce infrared radiation, thereby cooling the climate. Initial research would model and test covering 1000-5000 square miles to assess feasibility and climate impacts. If successful, full deployment from 2010-2070 would cover 67,000 square miles per year to offset projected warming until emissions controls take effect. The goal is to maintain 2010 temperature levels until transition to renewable energy is complete by 2070.
Enhancing the Efficiency of Solar Desalination through Computational Fluid Dy...IRJET Journal
This document summarizes a study that used computational fluid dynamics (CFD) modeling to simulate the operation of a single slope passive solar still and compare the simulation results to experimental data. The researchers created a detailed 3D model of the solar still in ANSYS Workbench and ran simulations in FLUENT under conditions matching real-world experiments. The temperatures predicted by the CFD model closely matched those observed in experiments, validating the model's accuracy. While some small differences occurred between the simulated and experimental results, the CFD data was able to reliably predict water output and heat transfer efficiency. This study demonstrates how CFD simulations can provide insight into improving the efficiency of passive solar desalination.
Best 20 SEO Techniques To Improve Website Visibility In SERPPixlogix Infotech
Boost your website's visibility with proven SEO techniques! Our latest blog dives into essential strategies to enhance your online presence, increase traffic, and rank higher on search engines. From keyword optimization to quality content creation, learn how to make your site stand out in the crowded digital landscape. Discover actionable tips and expert insights to elevate your SEO game.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
The present research shows the effect of dust accumulation on the surface of photovoltaic (PV) modules, which cause losses in their output power. We got 28% of losses in output power at Madinah city during 60 days of dust accumulation. Two ways were used to study the effect of dust on the PV modules of type monocrystalline silicon: the quantitative and the qualitative approaches respectively. A model based on dust density is used to determine the losses of output PV power. We propose to add an important parameter noted dust accumulation coefficient (%/mg.cm-2), in data sheet of PV modules manufacturer. In addition, an intelligent cleaning system is proposed, using the notion of dust density, to start cleaning when an admissible value of power losses is reached. This process allows minimizing the effect of dust.
This document reviews the effect of environmental factors like dust, temperature, and wind on photovoltaic module performance. Dust deposition reduces light transmission and module output, and high temperatures also decrease efficiency. Wind can help remove dust but also spread it; higher wind speeds generally result in lower module temperatures through increased cooling. The document examines past research on these impacts and promising strategies for mitigating dust accumulation, like electrostatic cleaning and surface treatments.
Experimental study of the impact of dust on azimuth tracking solar PV in Shar...IJECEIAES
Dust is one of the significant constraints in utilizing solar photovoltaic systems under harsh weather conditions in the desert regions due to creating a shadow that blocks solar irradiance from reaching solar cells and consequently, significantly reducing their efficiency. In this research, experimental study was performed to comprehend the nature of dust particles and their impact on the electrical power output that is generated from azimuth tracking solar PV modules under Sharjah environmental conditions in winter season. According to laboratory experiments, the power losses are linearly related to the dust accumulated density on the surface of the solar panel with a slope of 1.27% per g/m2. The conducted Outdoor studies revealed that the absolute reduction in output power increased by 8.46% after 41 continuous days with one low-intensity rainy day. The linear relationship obtained from indoor experiments was applied later to estimate the dust deposited density on the outdoor setup. The results showed that a regular cleaning process every two weeks is recommended to maintain the performance and to avoid the soiling loss. This work will help engineers in the solar PV plants to forecast the dust impact and figure out the regularity of the cleaning process in case of single axis tracking systems.
This document reviews various methods for cleaning solar photovoltaic panels to remove dust accumulation and improve efficiency. It discusses electrostatic cleaning systems that use electric fields to remove charged and uncharged dust particles. It also describes mechanical cleaning methods using wipers, brushes and vibrations driven by motors or piezoelectric transducers. Additionally, the document outlines microcontroller-based automatic cleaning robots and self-cleaning techniques using superhydrophobic coatings and nanoscale structures to prevent dust adhesion. Cleaning is important as dust deposition can reduce panel output by over 80% without maintenance.
This study examines the impact of four environmental factors - dust accumulation, water droplets, bird droppings, and partial shading conditions - on photovoltaic (PV) system performance. The results show that dust accumulation, shading, and bird fouling significantly reduce PV current, voltage, and harvested energy. Shading had the strongest negative effect, with power reduction of 33.7-92.6% depending on the shaded area. However, water droplets decreased PV panel temperature and slightly increased power output. Dust reduced power by 8.8% and efficiency by 11.86%. Bird fouling reduced performance by around 7.4%. The study provides quantitative analysis of how each factor individually affects key PV parameters and overall system
This study examines the impact of four environmental factors - dust accumulation, water droplets, bird droppings, and partial shading conditions - on photovoltaic (PV) system performance. The results show that dust accumulation, shading, and bird fouling significantly reduce PV current, voltage, and harvested energy. Shading had the strongest negative effect, with power reduction of 33.7-92.6% depending on the shaded area. However, water droplets decreased PV panel temperature and slightly increased power output. Dust reduced power by 8.8% and efficiency by 11.86%. Bird fouling reduced performance by around 7.4%. The study provides quantitative analysis of how each factor individually affects key PV parameters and overall system
Effect of pollution and dust on PV performanceIJCMESJOURNAL
This document summarizes an experimental study that evaluated the effect of three Iraqi construction materials (cement, plaster, and borax) on the performance of photovoltaic (PV) cells. The materials were applied in weights from 2 to 10 grams to PV cell samples. Plaster was found to have the greatest negative impact on current, power, and efficiency of the cells, reducing efficiency by up to 25.8% compared to clean cells. Borax had the smallest effect on current and caused the lowest degradation to PV cell performance. The results indicate the importance of keeping PV surfaces clean to maximize their economic benefits.
Case Study of Solar Power Plant Generation And Their Factors AffectingIRJET Journal
This document discusses factors affecting the performance of solar power plants. It begins by introducing solar energy as a renewable and sustainable energy source. It then discusses how environmental conditions like dust can impact the performance of photovoltaic systems, reducing power output. Various dust removal and panel coating techniques are examined from previous studies. Implementation costs for a 1MW ground-mounted solar plant are estimated to be around INR 4-5 crores. Expected power generation from such a plant in Tamil Nadu is around 4.5kW per kW of panels installed. The return on investment for a 1MW plant is estimated to be around 8.5 years. Proper site selection is also highlighted as an important factor influencing generation and material performance.
The document summarizes a study that measured photovoltaic (PV) performance, ambient dust levels, and weather conditions in Doha, Qatar from June to December 2014. Three PV arrays were monitored - one cleaned every week, one every two months, and one every six months. A "cleanness index" showed the arrays cleaned every six months lost on average 0.0042 of performance per day, while the two-month cleaned arrays lost 0.0045 per day. Daily changes in cleanness index were negatively correlated with dust levels and humidity but positively correlated with wind speed. A regression model related cleanness index changes to dust, wind, and humidity and showed dust deposition significantly reduced PV power generation
INFLUENCE OF SITE AND SYSTEM PARAMETERS ON THE PERFORMANCE OF ROOF-TOP GRID-C...IRJET Journal
This document analyzes the influence of site and system parameters on the performance of a 49.92 kW rooftop solar PV system in Belfast, Northern Ireland over five years. The researchers examined how ambient temperature, relative humidity, solar irradiation, wind speed, and air pressure (site parameters) as well as inverter efficiency, system performance ratio, and other metrics (system parameters) affected the system's output. Their results showed that higher temperatures, humidity, and solar irradiation decreased performance while higher wind speed increased it. Higher air pressure also increased solar irradiation and power output. The goal was to better understand how environmental conditions and system design impact the real-world efficiency of solar energy generation.
IRJET- Solar Panel Cleaning System with Inbuilt Power SupplyIRJET Journal
This document presents the design of an automated self-cleaning solar panel system with an inbuilt power supply. Dust and other debris accumulation on solar panels can reduce their efficiency by 5-30%. The designed system detects shading of solar cells using an Arduino controller and activates brush motors to clean the panels. It can clean 3 panel arrays in a row over 5 minutes. The cleaning mechanism is powered by a battery that is recharged by the solar panels when not in use. Future improvements discussed include drone-based cleaning and high voltage or ultrasonic cleaning methods.
Design and Development of a Dry-Cleaning System for Photovoltaic PanelsIRJET Journal
This document describes the design and development of a dry-cleaning system for photovoltaic panels. Dust accumulation on solar panels can reduce power production by up to 42%. The researchers designed an automatic cleaning robot that uses an Arduino microcontroller to travel along photovoltaic panels and remove dust using brushes. Testing showed the robot successfully cleaned dust off the panels and improved power output, demonstrating the viability of such a system for maintaining solar panel effectiveness over time. The document discusses various cleaning mechanisms proposed in other studies and outlines the design, methodology, results and conclusions of the researchers' dry-cleaning robot system.
effect of environmental variables on photovoltaic performance based on experi...IJCMESJOURNAL
This paper investigated the effect of environment variables on Photovoltaic PV performance. It is surely understood that local climate can dramatically affect the power generation from a PV system. The most obvious components are the solar radiation hitting the panels, air temperature, humidity and wind speed. The local climatic conditions and precipitation influence the extent to which the panels get to be dusty or polluted, which affects the electrical power generation. The high air temperature caused a reduction in the PV panel output power rated from 1.85 to 20.22%, as well as, increased relative humidity where the largest decline recorded was 32.24%. The wind has a cooling effect on the PV panel that limits the power reduction due to increased solar radiation or panel back temperature. Besides, the wind blows away the accumulated dust that enhances the resulted PV panel power.
In previous experiments, dust accumulation for the solar panels has been investigated for a long period of time which is approximately one year [1]. The experiments have been done in different countries which have climate conditions of the dusty weather. Those countries are Iraq, Egypt and UAE. The solar panels were never cleaned, firstly for one month, secondly for two months and so on. The results were there was a decreasing in the transmittance of the solar panels, which is emphasize the effect of accumulated dust, even though the changing in the tilt angel which is in conjunction with the dust deposition on the panels. A well designed auto cleaning system to clean the solar panels will be added to the panels to keep the transmittance of the solar planes fixed approximately and to reduce the cost- of periodic cleaning
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The document reviews various solar distillation technologies for desalination. It discusses different types of solar concentrators and collectors that can be used to heat saline water and produce fresh water through distillation. Several studies that have tested different solar distillation designs and configurations are summarized. These include designs using parabolic concentrators, double pass solar air heaters, humidification-dehumidification processes, and systems combining multiple technologies. The document indicates that solar distillation is a promising technology for desalination using renewable energy but further improvements are needed to increase efficiency and competitiveness compared to conventional thermal desalination methods.
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Energies 12-02923-v2
1. energies
Article
Dust Removal from Solar PV Modules by Automated
Cleaning Systems
Abdulsalam S. Alghamdi 1 , AbuBakr S. Bahaj 1,2 , Luke S. Blunden 2 and Yue Wu 2,*
1 King Salman bin Abdulaziz Chair for Energy Research, & Electrical Engineering Department,
King Abdulaziz University, Jeddah 22254, Saudi Arabia
2 Energy & Climate Change Divisions, Sustainable Energy Research Group, School of Engineering,
Faculty of Engineering & Physical Sciences, University of Southampton, Southampton SO17 1BJ, UK
* Correspondence: phil.wu@soton.ac.uk; Tel.: +44-023-8059-3940
Received: 17 June 2019; Accepted: 24 July 2019; Published: 29 July 2019
Abstract: Dust accumulation on solar photovoltaic (PV) modules reduces light transmission from the
outer surfaces to the solar cells reducing photon absorption and thus contributing to performance
reduction of PV systems. In regions such as the Middle East where dust is prevalent and rainfall is
scarce, remedial measures are needed to reduce such impacts. Currently, various techniques are being
employed to address such sand soiling ranging from mechanical (brushing) to active and passive
electrical interventions. This research focuses on mechanical approaches encompassing module
vibration, air and water jets, and combinations of these. A reconfigurable pilot-scale testbed of 8 kWp
PV plant was installed on a carport shading system within the campus of King Abdulaziz University
(KAU), Jeddah, Saudi Arabia. The functional PV carport was configured to allow water recovery and
re-use within the testbed. Here, we discuss the overall cleaning design philosophy and approach,
systems design, and how multiple cleaning configurations can be realised within the overall PV
carport. Results indicate that in this location, sand soiling has a significant effect on performance
of PV modules on a timescale of days. In addition, water jets optimised for high volume and low
pressure were effective at reducing sand soiling with array power output increasing by over 27%,
whilst air jets and module vibration were less effective in reducing soiling to an acceptable level.
Overall, the testbed has provided a new approach to testing a combination of cleaning solutions in the
field coupled with used water recovery. The proposed approach is important, as currently, there are a
large number of solar PV projects being built in Saudi Arabia with more being planned for the future.
Keywords: solar photovoltaics; PV arrays conversion losses; PV operational and environmental
conditions; mechanical cleaning systems; dust deposition and removal; PV energy yield
1. Introduction
The use of solar photovoltaic (PV) systems for electricity production is expanding with over
390 GWp already installed globally [1]. Rapid expansion of PV technology is occurring in sunny areas
in countries such as those in the Middle East, Northern Africa, Australia, India, China, Latin America,
and the United States of America [1]. Due to the wide availability of solar resource and advancements
in conversion technologies, solar energy is fast emerging as a cost-effective source for power generation,
with grid parity being achieved in many solar resource-rich countries [1,2].
In solar photovoltaics (PV), the efficiency of the overall system has increased through many
improvements in cell efficiency, balance of system, and overall management and control [3]. However,
one of the issues outside the scope of such improvements is the effect of environmental conditions, such
as the deposition of foreign particles on module surfaces of a solar PV array [4]. This could be sand,
salt, bird droppings, snow, etc. Such deposits reduce the light transmission through the glass cover of
Energies 2019, 12, 2923; doi:10.3390/en12152923 www.mdpi.com/journal/energies
2. Energies 2019, 12, 2923 2 of 21
the modules impacting photon absorption by the solar cells [5,6]. As deposition increases, it results in
progressive conversion efficiency losses and hence reduced energy yields from the modules and the
overall array [7]. For example, it was shown that in one month the output from an outdoor PV system
in Saudi Arabian conditions reduced by over 5% due to dust accumulation [8]. A similar experiment in
Abu Dhabi showed a reduction of PV output of around 13% for a similar period [9]. In a review of over
eighty recent publications, it was found that the loss in power generation due to dust accumulation on
solar PV systems can exceed 40% [10]. Such reduction, which is often quantified by the soiling rate, is
found to be strongly affected by four factors: (1) geographic location; (2) physical properties of dust
particles, such as size; (3) PV module surface roughness; and (4) weather conditions [11]. Other studies
showed that there is a clear difference of particle sizes from sand collected from Saudi Arabia and
Iraq, which leads to a different level of soiling rate [12]. Similar observations were made in a study
comparing sand samples showing significant difference of particle size from Doha and Namibia [5].
Furthermore, weather conditions such as rainfall frequency, humidity, and wind velocity have
been studied to reveal their influence on soiling rate. For example, it was found that long-lasting rains
were capable of cleaning dust or dirt off solar panels, but their effectiveness varies heavily among
different seasons with observed system performance loss exceeding 20% during dry summer season [13].
Additionally, it was observed that if a sandstorm and rainfall happen simultaneously, then the soiling
rate is even greater as the accumulated sand adhered strongly to the panel surface, making the
subsequent cleaning more difficult [14]. Further studies on soiling rate in Saudi Arabia, where the
deposition of dust varies significantly between seasons from 5 g/m2/month (July) to 28 g/m2/month
(August and October) [15], showed significant dust accumulation due to moisture and humidity,
particularly from early-morning dews [12,16]. Other studies on the influence of wind velocity on dust
accumulation found it to be insignificant [17]. Results of monitoring the characteristics of dust in
Jeddah, Saudi Arabia, showed that its composition varied significantly as a function of changes in
weather conditions [18]. The concentration of crustal elements (Si, Ca, Na, Al, Fe, K, and Mg) increased
from 45% to 68% after dust storm events, indicating the origin of the dust deposited by the storms is
largely from non-anthropogenic sources, whereas the reverse is true under normal conditions [18].
Approaches already employed to prevent or remove such deposition vary in terms of technologies
and effectiveness. The work in [19] summarised existing cleaning methods into three categories:
Mechanical cleaning, passive approaches using coating materials, and electrodynamic screen (EDS)
cleaning. Mechanical cleaning systems commonly comprise either brushes or silicone blades,
with additional usage of water to improve the cleaning efficiency [4]. Mechanical cleaning systems in
real applications will need to be individually adjusted to achieve optimal performance, as the proper
level of force and pressure vary among different locations [19]. However, such systems consume
a considerable amount of water, which is particularly challenging for desert regions facing water
scarcity [20]. In addition, the brush or wiper systems are likely to cause damage to PV panel surfaces,
hence performance losses, requiring regular maintenance and high upfront investment [6].
Currently, coating for solar systems uses either super-hydrophobic or hydrophilic material [21,22]
with new transparent super-hydrophobic surfaces being designed for better durability [23]. However,
although the coating materials are effective as applied, their durability and lifetime still require future
validation [6,20]. Similarly, the application of electrodynamic screens has also shown high efficiency in
terms of cleaning, but the screens degrade after a period of use and were found to be less effective
when the modules were wet [6,24].
In summary, dust deposits can cause significant performance reductions in certain locations and
while a number of approaches to cleaning and prevention have been subjected to previous research,
there remains a gap for solutions which are both low-maintenance and robust while minimising use
of water and energy. This research addresses such issues and delivers a study to understand how
modules in an array can be cleaned through sequences of interventions encompassing water jets, air jets,
mechanical vibrations, and combinations of these. These interventions are set up on a pilot-scale
testbed in Jeddah, Saudi Arabia, that can be remotely operated from anywhere in the world. The aim
3. Energies 2019, 12, 2923 3 of 21
of the testing is to provide an optimised approach for cleaning solar PV modules that can be scaled up
for use in large-scale PV arrays. The following sections provide an indication of the system design
philosophy, detailed descriptions of the approaches undertaken, and results achieved.
2. Methodology
The pilot project is situated on the campus of King Abdulaziz University (KAU) in Jeddah,
Kingdom of Saudi Arabia (KSA), where, as mentioned above, significant dust deposition and storms
can occur, and the background level of soiling is high. The cleaning design philosophy presented here
addresses such impacts through a combination of weather and performance event monitoring which
will activate the automated cleaning processes. Specifically, the approach encompasses: (1) monitoring
the amount of dust deposition on solar systems and the degradation in PV performance, (2) controlling
the system in response to commands to operate various cleaning elements either separately or in
combination, and (3) investigating the effectiveness of each cleaning intervention.
2.1. Overall System Design Philosophy
As briefly indicated above, the systems developed and implemented were designed to serve
as a test bed where different cleaning modes can be tested and their performance determined and
compared. The latter is accomplished through observations of improvement, or otherwise of the
energy yield as outputs from the cleaned solar PV arrays. In addition to the infrastructure (carport) on
which the deployed pilot plant was built, there are three major components incorporated to support
cleaning and monitoring. Figure 1 depicts components, consisting of: (1) solar PV array, balance of
systems and battery storage; (2) cleaning systems; and (3) remote control and data collection unit.
Full descriptions of these systems are given in Sections 2.2–2.9. The whole plant was designed to be
remotely managed, monitored, and controlled. This includes the scheduling of different cleaning modes
and any combination of these, as well as determining the effect of such tests on array performance.
Furthermore, the system can also be operated fully automatically, whilst detailed data are continuously
collected and stored in an online cloud storage platform for later analysis (Section 2.8).
Energies 2019, 12, x FOR PEER REVIEW 3 of 22
of the testing is to provide an optimised approach for cleaning solar PV modules that can be scaled
up for use in large-scale PV arrays. The following sections provide an indication of the system design
philosophy, detailed descriptions of the approaches undertaken, and results achieved.
2. Methodology
The pilot project is situated on the campus of King Abdulaziz University (KAU) in Jeddah,
Kingdom of Saudi Arabia (KSA), where, as mentioned above, significant dust deposition and storms
can occur, and the background level of soiling is high. The cleaning design philosophy presented
here addresses such impacts through a combination of weather and performance event monitoring
which will activate the automated cleaning processes. Specifically, the approach encompasses: 1)
monitoring the amount of dust deposition on solar systems and the degradation in PV performance,
2) controlling the system in response to commands to operate various cleaning elements either
separately or in combination, and 3) investigating the effectiveness of each cleaning intervention.
2.1. Overall System Design Philosophy
As briefly indicated above, the systems developed and implemented were designed to serve as
a test bed where different cleaning modes can be tested and their performance determined and
compared. The latter is accomplished through observations of improvement, or otherwise of the
energy yield as outputs from the cleaned solar PV arrays. In addition to the infrastructure (carport)
on which the deployed pilot plant was built, there are three major components incorporated to
support cleaning and monitoring. Figure 1 depicts components, consisting of: (1) solar PV array,
balance of systems and battery storage; (2) cleaning systems; and (3) remote control and data
collection unit. Full descriptions of these systems are given in Sections 2.2 to 2.9. The whole plant was
designed to be remotely managed, monitored, and controlled. This includes the scheduling of
different cleaning modes and any combination of these, as well as determining the effect of such tests
on array performance. Furthermore, the system can also be operated fully automatically, whilst
detailed data are continuously collected and stored in an online cloud storage platform for later
analysis (Section 2.8).
Figure 1. Schematic diagram of plant components and their connections for array performance, cleaning
scheduling, control and monitoring. * Dump load will be used to extend the period for photovoltaic
(PV) systems to continue operation. In real applications, dump loads are not needed as PV systems
would be grid connected.
4. Energies 2019, 12, 2923 4 of 21
The design philosophy was informed by a series of laboratory investigations in which sand
samples from the KAU site, Jeddah, west of Saudi Arabia, were used in a laboratory-scale rig containing
solar PV modules to simulate the dust soiling and initial cleaning approach. The tests focused on
the dislodgement of sand through various interventions, such as vibration, water jets and air jets,
and a combination of these (Figure 2). The preliminary results from these tests showed that cleaning
methods using vibration, water and air jets were able to reduce sand deposition on PV modules. These
gave confidence in the approach and allowed progression to design the larger pilot-scale testbed for
experimentation at the site in Jeddah.
Energies 2019, 12, x FOR PEER REVIEW 4 of 22
Figure 1. Schematic diagram of plant components and their connections for array performance,
cleaning scheduling, control and monitoring. *Dump load will be used to extend the period for
photovoltaic (PV) systems to continue operation. In real applications, dump loads are not needed as
PV systems would be grid connected.
The design philosophy was informed by a series of laboratory investigations in which sand
samples from the KAU site, Jeddah, west of Saudi Arabia, were used in a laboratory-scale rig
containing solar PV modules to simulate the dust soiling and initial cleaning approach. The tests
focused on the dislodgement of sand through various interventions, such as vibration, water jets and
air jets, and a combination of these (Figure 2). The preliminary results from these tests showed that
cleaning methods using vibration, water and air jets were able to reduce sand deposition on PV
modules. These gave confidence in the approach and allowed progression to design the larger pilot-
scale testbed for experimentation at the site in Jeddah.
Figure 2. Laboratory-scale cleaning performance test in the UK prior to pilot system design and
deployment.
An outdoor car park in the KAU campus was chosen to deploy the developed power plant and
the cleaning system and conduct the in situ tests. The car parks areas in KAU represent around 50%
of the campus footprint, having considerable potential for contributing to the power demand of the
university through deploying PV systems at scale on carports [25].
Some of the components of the plant were pre-assembled into two weatherproof enclosures and
pre-tested in the UK to allow rapid installation on site. A weather station and two pairs of CCTV
cameras were added to the system to provide weather condition monitoring, visual inspection and
monitoring of the environmental conditions and dust build-up on the modules. Figure 3 shows the
outline of the pilot plant testbed and position of the various components deployed on a working
(functioning) carport.
Figure 2. Laboratory-scale cleaning performance test in the UK prior to pilot system design and deployment.
An outdoor car park in the KAU campus was chosen to deploy the developed power plant and
the cleaning system and conduct the in situ tests. The car parks areas in KAU represent around 50%
of the campus footprint, having considerable potential for contributing to the power demand of the
university through deploying PV systems at scale on carports [25].
Some of the components of the plant were pre-assembled into two weatherproof enclosures and
pre-tested in the UK to allow rapid installation on site. A weather station and two pairs of CCTV
cameras were added to the system to provide weather condition monitoring, visual inspection and
monitoring of the environmental conditions and dust build-up on the modules. Figure 3 shows the
outline of the pilot plant testbed and position of the various components deployed on a working
(functioning) carport.
Energies 2019, 12, x FOR PEER REVIEW 5 of 22
Figure 3. Outline of the pilot plant testbed and position of the various components deployed on a
functioning carport.
2.2. Carport
The carport structure not only provides shading for vehicles but also serves as the base for the
solar PV modules, the cleaning systems, and other accessories. The structure, therefore, needs to have
a high level of structural integrity, ability to mount solar modules, and flexibility for future
modifications. To ease design needs and deployment and provide overall robustness for the plant, a
Figure 3. Outline of the pilot plant testbed and position of the various components deployed on a
functioning carport.
5. Energies 2019, 12, 2923 5 of 21
2.2. Carport
The carport structure not only provides shading for vehicles but also serves as the base for the
solar PV modules, the cleaning systems, and other accessories. The structure, therefore, needs to have a
high level of structural integrity, ability to mount solar modules, and flexibility for future modifications.
To ease design needs and deployment and provide overall robustness for the plant, a commercial
product by Schletter® (schletter-group.com), Park-Sol-B1 (Schletter Solar GmbH, Kirchodorf, Germany),
was selected. This consisted of an aluminium roof structure, mounting rails for installing PV panels,
cast-in-place concrete foundations (constructed on site), and a steel main structure to support additional
loads. The carport is able to accommodate four parked vehicles, occupying a total area of ~65 m2
(12.0 × 5.4 m, excluding spaces occupied by the foundations and water tank). Details of the structure
as well as some of the systems installed are given in Figure 4.
Energies 2019, 12, x FOR PEER REVIEW 6 of 22
Figure 4. (a–c) Schematic and dimension of carport structure, foundation, balance of system
enclosures, water supply, and recovery system.
The roof of the structure has a 10° inclination, which allows rainwater or water from cleaning to
be drained away from solar panels into a collection gutter. The water is collected by aluminium
panels fitted under the modules, allowing the water to flow into the gutter installed on the lower end
of the roof and then through pipework connected to the underground water storage tank (marked in
Figure 4c). Before entering the water storage tank, the water passes through a three-stage water filter
unit to remove sand, dust, and debris (not shown in Figure 4c). The water storage and reuse system
is discussed further in Section 2.5.
The roof of the carport structure is composed of two main parts. On the top of the roof, six
aluminium rails were installed horizontally (Figure 4c), serving as the base where PV modules can
be mounted. The space between each rail is around 0.8 m and can be adjusted, allowing the layout of
the PV modules to be rearranged, in the future, to accommodate different cleaning systems.
Aluminium sheeting was fitted underneath the mounting rails to provide a weatherproof barrier
from sunlight, dust, and as indicated earlier to collect the water used by the different cleaning
systems. The sheeting also prevents parked vehicles and passengers from being affected by the
cleaning processes.
Figure 4. (a–c) Schematic and dimension of carport structure, foundation, balance of system enclosures,
water supply, and recovery system.
The roof of the structure has a 10◦ inclination, which allows rainwater or water from cleaning
to be drained away from solar panels into a collection gutter. The water is collected by aluminium
panels fitted under the modules, allowing the water to flow into the gutter installed on the lower end
of the roof and then through pipework connected to the underground water storage tank (marked in
Figure 4c). Before entering the water storage tank, the water passes through a three-stage water filter
unit to remove sand, dust, and debris (not shown in Figure 4c). The water storage and reuse system is
discussed further in Section 2.5.
6. Energies 2019, 12, 2923 6 of 21
The roof of the carport structure is composed of two main parts. On the top of the roof, six
aluminium rails were installed horizontally (Figure 4c), serving as the base where PV modules can be
mounted. The space between each rail is around 0.8 m and can be adjusted, allowing the layout of the
PV modules to be rearranged, in the future, to accommodate different cleaning systems.
Aluminium sheeting was fitted underneath the mounting rails to provide a weatherproof barrier
from sunlight, dust, and as indicated earlier to collect the water used by the different cleaning systems.
The sheeting also prevents parked vehicles and passengers from being affected by the cleaning processes.
The total roof space provided by the carport structure is ~65 m2 (Figure 4). If fully utilised it could
accommodate a PV system with a capacity of up to 11 kWp. However, for our study this roof space
area was separated into sections (see Section 2.3) where different cleaning systems can be installed and
tested simultaneously. Figure 5 shows the final layout of the array and the carport space utilisation.
As can be seen in the figure, buffer zones between sections of each sub-array were created to try to
avoid any cross effect of cleaning modes being tested.
Energies 2019, 12, x FOR PEER REVIEW 7 of 22
utilisation. As can be seen in the figure, buffer zones between sections of each sub-array were created
to try to avoid any cross effect of cleaning modes being tested.
Figure 5. Layout of the array and the carport space utilisation, showing buffer zones between sections
to avoid any cross effect of cleaning modes being tested.
2.3. PV System
The photovoltaic modules used were manufactured by CanadianSolar®, model number
CS6K-270P (Canadian Solar, Cambridge, ON., Canada) with a dimension of 1650 × 992 × 40 mm (L ×
W × D) and a rated power of 275 Wp (Vmp = 31 V, Imp = 8.9 A). Our design consideration indicated that
on the site (Jeddah, Saudi Arabia), the typical working module temperature is estimated to be ~60 °C
and the irradiance is ~800 W/m2. Under such conditions, each module would have a peak power
output of 185 W (at approximately 28 V and 7 A). The PV system consists of 24 modules installed on
the carport structure, forming a 6 × 4 array, as shown in Figures 5 and 6. The whole array was
configured into eight parallel strings, each of which is composed of three modules that are connected
in series, as marked by red lines in Figure 6. Three of the strings: (S-I) A1-A2-A3, (S-V) A4-A5-A6,
and (S-III) B2-C2-D2 are used as a control and are not fitted with any of the cleaning systems.
Figure 5. Layout of the array and the carport space utilisation, showing buffer zones between sections
to avoid any cross effect of cleaning modes being tested.
2.3. PV System
The photovoltaic modules used were manufactured by CanadianSolar®, model number
CS6K-270P (Canadian Solar, Cambridge, ON, Canada) with a dimension of 1650 × 992 × 40 mm
(L × W × D) and a rated power of 275 Wp (Vmp = 31 V, Imp = 8.9 A). Our design consideration indicated
that on the site (Jeddah, Saudi Arabia), the typical working module temperature is estimated to be
~60 ◦C and the irradiance is ~800 W/m2. Under such conditions, each module would have a peak
power output of 185 W (at approximately 28 V and 7 A). The PV system consists of 24 modules installed
on the carport structure, forming a 6 × 4 array, as shown in Figures 5 and 6. The whole array was
configured into eight parallel strings, each of which is composed of three modules that are connected
in series, as marked by red lines in Figure 6. Three of the strings: (S-I) A1-A2-A3, (S-V) A4-A5-A6,
and (S-III) B2-C2-D2 are used as a control and are not fitted with any of the cleaning systems.
7. Energies 2019, 12, 2923 7 of 21
and the irradiance is ~800 W/m2. Under such conditions, each module would have a peak power
output of 185 W (at approximately 28 V and 7 A). The PV system consists of 24 modules installed on
the carport structure, forming a 6 × 4 array, as shown in Figures 5 and 6. The whole array was
configured into eight parallel strings, each of which is composed of three modules that are connected
in series, as marked by red lines in Figure 6. Three of the strings: (S-I) A1-A2-A3, (S-V) A4-A5-A6,
and (S-III) B2-C2-D2 are used as a control and are not fitted with any of the cleaning systems.
Figure 6. Layout of solar modules, PV strings and cleaning systems on carport canopy (plan view).
Figure 6. Layout of solar modules, PV strings and cleaning systems on carport canopy (plan view).
Such a layout provides an appropriate platform to test multiple cleaning modes either individually
or simultaneously in combination for specific PV sub-arrays and to compare the outcomes with the
performance determined from control strings where no cleaning takes place. For cleaning, eight sets of
water nozzles and three sets of pressurised air nozzles (B1, C1, and D1, string S-II) were fitted on top of
11 of the PV modules, as shown in Figure 6, where the arrows marked on the cleaning systems indicate
direction of water and airflow. In addition, six modules were also fitted with vibration motors to test
the performance of cleaning with vibration only (B6, C6, and D6, S-VIII). The other three modules—B5,
C5, and D5 (S-VII)—have both water cleaning and vibration fitted to test the effectiveness of cleaning
by combining vibration and water modes.
As shown in Figures 5 and 6, the PV module D4 (in string S-VI), unlike D3 (S-IV), is not fitted
with water nozzles. This feature is added to compare water jet cleaning reach where D4 is cleaned
through drenching from the nozzle jets on C4. This is implemented to see if this mode is sufficient to
clean subsequent modules in an array where huge savings in water use could be gained, especially in
large arrays.
2.4. Energy Storage System
In Saudi Arabia, connecting microgeneration, such as PV to the distribution network is currently
not straightforward from a regulatory standpoint. A predicate of the design philosophy is that the
plant and its systems should be run independently (standalone) and not connected to the mains (grid).
Hence, a battery storage unit with charge controllers and an inverter was installed as part of the overall
PV system, as shown in Figure 7. Gel batteries (lead acid) were chosen based on their high temperature
safety and cost effectiveness for static applications. They have a total capacity of 9.6 kWh (48 V, 200 Ah),
providing 24-hour power for all cleaning systems and additional loads, such as data logging, safety
lighting, and cameras. The PV modules were separated into two arrays, each containing 12 modules
with a rated capacity of 3.3 kW (36 A, 93 V). Each array is then connected to an individual charge
controller (45 A, 150 V), which manages the state-of-charge of the batteries. As lead acid batteries
are known to be prone to deep discharge, the charge controllers are programmed to maintain the
state-of-charge at over 50%.
8. Energies 2019, 12, 2923 8 of 21
(48 V, 200 Ah), providing 24-hour power for all cleaning systems and additional loads, such as data
logging, safety lighting, and cameras. The PV modules were separated into two arrays, each
containing 12 modules with a rated capacity of 3.3 kW (36 A, 93 V). Each array is then connected to
an individual charge controller (45 A, 150 V), which manages the state-of-charge of the batteries. As
lead acid batteries are known to be prone to deep discharge, the charge controllers are programmed
to maintain the state-of-charge at over 50%.
Figure 7. PV system schematic showing the two sub-arrays, their connection to the balance of systems,
and energy storage.
Solar systems installed in car parks are likely to be grid-connected [25]. To facilitate future
studies in this area, the project was also designed to allow connectivity to the grid through a multi-
Figure 7. PV system schematic showing the two sub-arrays, their connection to the balance of systems,
and energy storage.
Solar systems installed in car parks are likely to be grid-connected [25]. To facilitate future studies
in this area, the project was also designed to allow connectivity to the grid through a multi-purpose
inverter—Victron Quattro. This provided the operational functions needed by the design philosophy,
as follows:
• Mode 1: System in an off-grid mode: The direct current (DC) from the batteries is inverted to
alternating current (AC) to power up the monitoring systems; data logging; cleaning systems,
such as the compressor and water pump (see Section 2.5); and dump loads;
• Mode 2: System is in a grid-connected mode where the inverter serves as a grid-tie inverter
allowing the metered power output to be directly exported to national grid.
In this presented work, we only consider Mode 1, where the inverter is set to be part of an
off-grid system, and the connection to the national grid is temporarily disabled. In order to simulate a
grid-like current sink for the PV system, a 4 kW dump load was incorporated to the system. This was
programmed to be automatically switched on when the current drops below the optimum, forcing a
no disconnect from the charge controllers, so the PV system stays operational to study cleaning modes
and their impacts on the energy yield.
In order to quantify PV system performance, the current of each PV string is monitored and
measured independently through a series of 6 mΩ shunts (60 mV at 10 A) installed within the system
cabinet. In addition, shunts (60 mV at 500 A) were also installed to monitor total PV current and battery
charging current. All of the measured data are collected by a data logger and stored in a cloud-based
database (see Section 2.8).
The batteries and all energy management devices are contained in a weatherproof enclosure
(IP 66), as shown in Figure 8. The enclosure is air conditioned, preventing the electronic devices from
overheating. This is particularly important for applications in the Middle East and other tropical
regions, where daytime ambient temperature often exceed 40 ◦C (50 ◦C on occasion), which may cause
damage to electronic components. The air conditioning unit has a rated capacity of 1 kWthmeral, and the
temperature set point can be adjusted to maintain the cabinet temperature at a required level.
9. Energies 2019, 12, 2923 9 of 21
The batteries and all energy management devices are contained in a weatherproof enclosure (IP
66), as shown in Figure 8. The enclosure is air conditioned, preventing the electronic devices from
overheating. This is particularly important for applications in the Middle East and other tropical
regions, where daytime ambient temperature often exceed 40 °C (50 °C on occasion), which may
cause damage to electronic components. The air conditioning unit has a rated capacity of 1 kWthmeral,
and the temperature set point can be adjusted to maintain the cabinet temperature at a required level.
Figure 8. Enclosure and assembly for energy storage unit showing the layout of the balance of system
components and the position of the air conditioning unit.
2.5. Water Cleaning System
Figure 8. Enclosure and assembly for energy storage unit showing the layout of the balance of system
components and the position of the air conditioning unit.
2.5. Water Cleaning System
As mentioned in Section 2.2, the water-based cleaning systems draw water from a 2 m3 capacity
underground water tank. The inspection cap is accessible from above via a manhole cover. Figure 9
shows the connection of components in the water cleaning system. A three-stage water filter unit was
fitted between the PV roof downpipe and the water tank. It is composed of three settling basins (1 m3
each) and three replaceable filters, accessible via manhole covers. The filter unit is able to prevent large
debris and significantly reduce dust and sand particle ingress into the water storage tank.
Energies 2019, 12, x FOR PEER REVIEW 10 of 22
As mentioned in Section 2.2, the water-based cleaning systems draw water from a 2 m3 capacity
underground water tank. The inspection cap is accessible from above via a manhole cover. Figure 9
shows the connection of components in the water cleaning system. A three-stage water filter unit was
fitted between the PV roof downpipe and the water tank. It is composed of three settling basins (1 m³
each) and three replaceable filters, accessible via manhole covers. The filter unit is able to prevent
large debris and significantly reduce dust and sand particle ingress into the water storage tank.
Figure 9. Connection of elements in water cleaning system.
Within the tank, a pressure sensor was installed to monitor both the loss of water from the
cleaning systems and detect any rainfall that may occur. The tank is also connected to the mains water
supply, allowing it to be topped up when the water surface drops below a certain level. This drop
could be caused by water losses during cleaning or water recollection process, i.e., spray droplets
blown away from the canopy, evaporation, and any slight leaks from the guttering and downpipes.
A water meter was installed on the main water supply with a magnetic pick-up (1 pulse per 0.25
litres) to measure the amount of water that has been added into the tank, reflecting the amount of net
Figure 9. Connection of elements in water cleaning system.
Within the tank, a pressure sensor was installed to monitor both the loss of water from the cleaning
systems and detect any rainfall that may occur. The tank is also connected to the mains water supply,
10. Energies 2019, 12, 2923 10 of 21
allowing it to be topped up when the water surface drops below a certain level. This drop could be
caused by water losses during cleaning or water recollection process, i.e., spray droplets blown away
from the canopy, evaporation, and any slight leaks from the guttering and downpipes. A water meter
was installed on the main water supply with a magnetic pick-up (1 pulse per 0.25 L) to measure the
amount of water that has been added into the tank, reflecting the amount of net water consumption.
Both the water depth sensor and water meter are connected to a data logger (see Section 2.8). The data
logger is able to collect water depth data and control a solenoid valve, which regulates the amount of
water entering the water tank from the main water supply.
Water stored in the underground tank is lifted and pressurized by a self-priming electrical pump,
configured to maintain a constant pressure in the pipework, and sprayed out of eight sets of water
nozzles, as shown in Figure 10. Each PV module is cleaned by a set of three nozzles (Figure 10),
which can be switched on and off by a programmable logic controller (PLC) unit through an electric
solenoid valve. The height of the water pipes and nozzles are controlled by a number of supporting
studs and are fully adjustable. This feature allows experimentation with nozzle height for effective
cleaning as well as determining the impact of water pipe shadows casted on the PV modules. As shown
in Figure 10, the cleaning systems on different PV strings are fitted at various heights, facilitating a
cross comparison in order to identify the optimal height. The water nozzles can also be adjusted to
optimize the spray angle, water volume and pressure. This is part of the design philosophy to study
and identify the most efficient method of cleaning for the PV solar systems whilst minimizing energy
and resource consumption.
Energies 2019, 12, x FOR PEER REVIEW 11 of 22
Figure 10. Cleaning systems on different PV strings fitted with nozzle where height can be varied.
The water nozzles can also be adjusted to optimise the spray angle, water volume, and pressure. Note
shading on modules due to pipework.
2.6. Air Cleaning System
There is a paucity of information on using pressurized air to clean solar PV modules. To address
this, a compressed air knife unit manufactured by Exair Corporation, model number 9078 (Figure 11),
was used to provide cleaning for the set of modules highlighted in Figure 6. Each unit has two
compressed air inlets, one at each end of the unit, controlled jointly by a solenoid valve and the PLC.
The compressed air is then driven through a narrow slot onto the solar modules.
Figure 10. Cleaning systems on different PV strings fitted with nozzle where height can be varied.
The water nozzles can also be adjusted to optimise the spray angle, water volume, and pressure.
Note shading on modules due to pipework.
2.6. Air Cleaning System
There is a paucity of information on using pressurized air to clean solar PV modules. To address
this, a compressed air knife unit manufactured by Exair Corporation, model number 9078 (Figure 11),
was used to provide cleaning for the set of modules highlighted in Figure 6. Each unit has two
11. Energies 2019, 12, 2923 11 of 21
compressed air inlets, one at each end of the unit, controlled jointly by a solenoid valve and the PLC.
The compressed air is then driven through a narrow slot onto the solar modules.
shading on modules due to pipework.
2.6. Air Cleaning System
There is a paucity of information on using pressurized air to clean solar PV modules. To address
this, a compressed air knife unit manufactured by Exair Corporation, model number 9078 (Figure 11),
was used to provide cleaning for the set of modules highlighted in Figure 6. Each unit has two
compressed air inlets, one at each end of the unit, controlled jointly by a solenoid valve and the PLC.
The compressed air is then driven through a narrow slot onto the solar modules.
Figure 11. Main elements in air cleaning nozzles.
For testing purposes, the compressed air for the system was provided by a mobile compressor
providing approximately 0.05 m3/s at 7 bar. In the future, this will be replaced by an electrical
compressor powered by the PV system, coupled to a large air receiver.
2.7. Module Vibration System
A series of vibration units were fitted into the back of the modules to test the potential of using
vibration as a water-free method of cleaning PV modules, as shown in Figure 12. Each unit is
composed of a 12 V electric motor and an unbalanced weight, in a waterproof case. Prior to the
installation on site, a range of vibration motors were tested in the laboratory trial mentioned earlier,
Figure 11. Main elements in air cleaning nozzles.
For testing purposes, the compressed air for the system was provided by a mobile compressor
providing approximately 0.05 m3/s at 7 bar. In the future, this will be replaced by an electrical
compressor powered by the PV system, coupled to a large air receiver.
2.7. Module Vibration System
A series of vibration units were fitted into the back of the modules to test the potential of using
vibration as a water-free method of cleaning PV modules, as shown in Figure 12. Each unit is composed
of a 12 V electric motor and an unbalanced weight, in a waterproof case. Prior to the installation
on site, a range of vibration motors were tested in the laboratory trial mentioned earlier, where the
performance of the motors at different speeds and weights was tested. It was found that the best
motor speed was in the range of 6000 to 8000 RPM, and heavier weights produced stronger motion of
sand particles. Moreover, it was also observed that (i) each PV module will require more than three
motors working simultaneously to remove dust and (ii) fixing motors loosely enhanced the vibration
effect due to the direct hammer impulse of the case striking the panel. As a result, each PV module
assigned to vibration test was fitted with five vibration motors, which are installed on the back of the
modules (Figure 6). These five motors were mounted at each of the four corners and one in the centre
of the module.
Energies 2019, 12, x FOR PEER REVIEW 12 of 22
where the performance of the motors at different speeds and weights was tested. It was found that
the best motor speed was in the range of 6000 to 8000 RPM, and heavier weights produced stronger
motion of sand particles. Moreover, it was also observed that (i) each PV module will require more
than three motors working simultaneously to remove dust and (ii) fixing motors loosely enhanced
the vibration effect due to the direct hammer impulse of the case striking the panel. As a result, each
PV module assigned to vibration test was fitted with five vibration motors, which are installed on the
back of the modules (Figure 6). These five motors were mounted at each of the four corners and one
in the centre of the module.
Figure 12. Configuration of vibration units underneath solar modules.
2.8. Data Acquisition and Control
A Gill Maximet 501 ® (Gill Instruments Limited, Lymington, UK) weather station (Figure 13)
was installed at 6 m above ground level in order to (a) record relevant variables relating to PV
performance and dust accumulation and (b) to provide a signal to control the switching on of the
dump load when the PV current drops below optimum for given irradiance. The weather variables
Figure 12. Configuration of vibration units underneath solar modules.
12. Energies 2019, 12, 2923 12 of 21
2.8. Data Acquisition and Control
A Gill Maximet 501® (Gill Instruments Limited, Lymington, UK) weather station (Figure 13) was
installed at 6 m above ground level in order to (a) record relevant variables relating to PV performance
and dust accumulation and (b) to provide a signal to control the switching on of the dump load when the
PV current drops below optimum for given irradiance. The weather variables measured at two-minute
intervals include air pressure, temperature, relative humidity, wind speed, wind direction, and irradiance.
Figure 12. Configuration of vibration units underneath solar modules.
2.8. Data Acquisition and Control
A Gill Maximet 501 ® (Gill Instruments Limited, Lymington, UK) weather station (Figure 13)
was installed at 6 m above ground level in order to (a) record relevant variables relating to PV
performance and dust accumulation and (b) to provide a signal to control the switching on of the
dump load when the PV current drops below optimum for given irradiance. The weather variables
measured at two-minute intervals include air pressure, temperature, relative humidity, wind speed,
wind direction, and irradiance.
Figure 13. Weather station and CCTV cameras.
The electrical variables (string currents and voltages), along with the water tank depth and water
meter are logged at 1-minute intervals by the Datataker® DT85M (Thermo Fisher Scientific Ltd,
Figure 13. Weather station and CCTV cameras.
The electrical variables (string currents and voltages), along with the water tank depth and water
meter are logged at 1-min intervals by the Datataker® DT85M (Thermo Fisher Scientific Ltd, Waltham,
MA, USA) data-logger networked with a Raspberry Pi (Raspberry Pi Foundation, Cambridge, UK),
in turn allowing secure two-way communications with a cloud-based server. The weather station
communicates with the data-logger over an SDI-12 bus.
In order to visually monitor the system remotely, 4 CCTV cameras with 5-megapixel resolution
(Swann Platinum Digital HD, SWNVK-474502, Swann Communications Pty. Ltd., Victoria, Australia),
have been installed on the site providing live streaming to the project portal (Figures 3 and 13).
The cameras were fixed on two of the car park lampposts (5 m high), allowing a clear visual range for
monitoring the PV panels and the carport system. The CCTV cameras were also linked to a digital
video recorder (DVR) which is connected to the system router, where images of the carport can be
viewed live or played back remotely. The DVR has the capacity of recording views for 80 days onto the
1 TB hard disk. The cameras are able to obtain clear views of the PV and cleaning systems, as well as the
functionality of various cleaning methods. In addition to the quantitative measurements and testbed
local observations, these networked cameras provide online imagery to allow qualitative comparison
of dust build-up on the different sets of PV modules.
2.9. Cleaning System Installation Configuration and Control
Programmed cleaning routines were established encompassing single and multiple intervention
combinations, which are controlled through the data logger. In order to detect the effectiveness of the
various cleaning modes employed to clean dust build-up on any of the strings (other than the control),
the cleaning programs are run on alternate days, as indicated in Table 1.
13. Energies 2019, 12, 2923 13 of 21
Table 1. Initial module cleaning routine. See Figure 5 for layout of PV array.
Programme
Day of Week
0 1 2 3 4 5 6
Air, S-II B1/C1/D1 B1/C1/D1 B1/C1/D1
Water only, S-IV B3/C3/D3 B3/C3/D3 B3/C3/D3
Water only, S-VI B4/C4 B4/C4 B4/C4
Vibration then
water, S-VII
B5/C5/D5 B5/C5/D5 B5/C5/D5
Vibration only,
S-VIII
B6/C6/D6 B6/C6/D6 B6/C6/D6
The operation of cleaning modes can be individually controlled by a programme that is designed
to provide flexibility of applying options of cleaning modes—including a manual setup at the control
panel. For example, the programme in Figure 14 provides a combination of two cleaning modes
(vibration and water jets) for the string S-VII comprising the PV modules B5, C5, and D5. Each vibration
pulse lasts 295 seconds (~5 minutes), followed by a water jet pulse of 30 seconds. The sequence of
vibration and water jet cleaning is designed to maximise the removal of dust, as the effectiveness
of the water jets is enhanced after dust has been mobilised and loosened by vibration. In addition,
the cleaning programme is initiated in sequence from top downwards, as shown in Figure 14, where
the water jet and vibration pulses for C5 only started after the cycle for B5 was completed.
Energies 2019, 12, x FOR PEER REVIEW 14 of 22
Figure 14. Example of cleaning programmes on string S-VII (B5/C5/D5) and string S-II (B1/C1/D1).
The compressed air cleaning programme for the string S-II, comprising B1/C1/D1, is also shown
in Figure 14. Each compressed air cleaning pulse lasts around 1 second due to the capacity of the
compressed air system. The length of compressed air cleaning operations is also chosen by taking
into account the complexity of physical processes involved in removing particles from surfaces such
as PV modules, which is an active area of research [26]. Particles require a threshold of shear stress
before they will move, and this will depend on the micro-level properties of the particles and PV
module surface and the level of humidity. The key variable of the effectiveness of the cleaning system
is air pressure, but the nature of turbulent and coherent fluctuations in air velocity have also been
shown in the literature to have a significant effect on particle removal [26]. The duration of the air
Figure 14. Example of cleaning programmes on string S-VII (B5/C5/D5) and string S-II (B1/C1/D1).
The compressed air cleaning programme for the string S-II, comprising B1/C1/D1, is also shown
in Figure 14. Each compressed air cleaning pulse lasts around 1 second due to the capacity of the
compressed air system. The length of compressed air cleaning operations is also chosen by taking into
account the complexity of physical processes involved in removing particles from surfaces such as PV
14. Energies 2019, 12, 2923 14 of 21
modules, which is an active area of research [26]. Particles require a threshold of shear stress before
they will move, and this will depend on the micro-level properties of the particles and PV module
surface and the level of humidity. The key variable of the effectiveness of the cleaning system is air
pressure, but the nature of turbulent and coherent fluctuations in air velocity have also been shown
in the literature to have a significant effect on particle removal [26]. The duration of the air pulse is
less significant, as air velocities of the order of tens of m/s mean that the time for a particle to cross
a PV module, once it has passed the threshold of motion, is extremely short. Therefore, in practice,
the duration of the pulse is more likely to be limited by the available air supply and the control system,
and longer pulses would be unlikely to improve cleaning effectiveness.
3. Results and Discussion
3.1. Effect of Vibration-Based Cleaning on Power Output
Observation of the performance of the sub-array under vibration cleaning was conducted between
5 and 17 February 2019. Prior to commencing the testing, all PV strings were manually cleaned with
water on 5 February to establish a common baseline. In order to determine the effect of vibration-based
cleaning, two strings (S-VII and S-VIII, see Figure 6) were subjected to 5 min of vibration, repeated
three times weekly, starting on 6 February. The power output from each PV string in the cleaned state
is therefore set at 100% as the baseline (index base). The power output measured during subsequent
days was compared with this baseline. As shown in Figure 15, the power outputs from the two
un-vibrated reference strings, S-V and S-VI, varied from 55% to 132%. The vibration-cleaned strings
(S-VII and S-VIII, right of Figure 15) show a similar variation in output from 52% to 136%. Hence,
the vibration cleaning did not show any noticeable performance improvements in output as compared
with the reference strings. Please note that the string S-VII is equipped with both water-cleaning
and vibration units, but during the period shown in Figure 15, only vibration was used to test its
cleaning effectiveness.
Energies 2019, 12, x FOR PEER REVIEW 15 of 22
cleaned strings (S-VII and S-VIII, right of Figure 15) show a similar variation in output from 52% to
136%. Hence, the vibration cleaning did not show any noticeable performance improvements in
output as compared with the reference strings. Please note that the string S-VII is equipped with both
water-cleaning and vibration units, but during the period shown in Figure 15, only vibration was
used to test its cleaning effectiveness.
Figure 15. Index of power production from vibration-cleaned strings (S-XII* and S-XIII) versus
reference (un-vibrated) strings (S-V and S-VI). *String S-VII is equipped with both vibration and water
cleaning units, but during this period only the vibration was used to test its cleaning efficiency.
In addition, Figure 15 also shows the global solar radiation that was measured by the on-site
weather station during the same period. The results show a close correlation with power productions
from the solar strings—both cleaned and reference strings.
3.2. Effect of Water-Based Cleaning on Power Output
Figure 15. Index of power production from vibration-cleaned strings (S-XII* and S-XIII) versus
reference (un-vibrated) strings (S-V and S-VI). *String S-VII is equipped with both vibration and water
cleaning units, but during this period only the vibration was used to test its cleaning efficiency.
15. Energies 2019, 12, 2923 15 of 21
In addition, Figure 15 also shows the global solar radiation that was measured by the on-site
weather station during the same period. The results show a close correlation with power productions
from the solar strings—both cleaned and reference strings.
3.2. Effect of Water-Based Cleaning on Power Output
The PV system is arranged in two sub arrays. For ease of comparison and consistency, we will
only consider cleaning of the strings that are connected to the same maximum power point tracker
(MPPT), namely strings S-V, S-VI, S-VII, and S-VIII. In order to determine the impact of water cleaning
on array output, two strings S-VI and S-VII (see Figure 6) were subjected to water cleaning only during
this period. The remaining two strings S-V and S-VIII were considered as reference and were not
cleaned. It should be noted that the string S-VIII is regarded here as a reference (non-cleaned) string
because no significant effect of the vibration-based cleaning was observed (see Section 3.1).
The water-cleaning programme (Table 1) started on 8 March 2019. Each of the water-cleaned
strings was subjected to cleaning three times per week. For each module with water jets fitted,
the module was drenched with water for 30 s (as shown in Figure 14). Figure 16 shows the mean
power output for 20 days from each string between 08:00 and 09:00 (local time). The figure indicates
that before commencing cleaning, the monitored sets of strings (S-V and S-VIII) show similar power
output. After water-based cleaning began, there is a clear improvement in the power output from the
water-cleaned strings (S-IV, S-VI and S-VII). For the time period selected, the output of cleaned strings
was 177 W (on average) compared to 140 W from that of the uncleaned strings (string S-II, S-III, S-V
and S-VIII, see Figure 6). This represents around 27% more power from the cleaned strings (standard
deviation, SD = 4.4%) over the 20 days compared to the non-cleaned strings.
Energies 2019, 12, x FOR PEER REVIEW 16 of 22
Figure 16. Difference in array performance between cleaned and non-cleaned sets of panels over a 20-
day period. Note all strings were equally soiled before twice-weekly cleaning commenced at the start
of the time period (28 March 2019).
The effect of the water cleaning system can also be seen from a visual comparison given in Figure
17, where the side-by-side string S-III (reference) and S-IV (water-cleaned) can be seen in a photo
taken in the evening when the water cleaning programme was commenced for the first time on 8
March. The image clearly shows that string S-III was covered by a considerable amount of dust,
whereas string S-IV was significantly clearer after water cleaning.
Figure 16. Difference in array performance between cleaned and non-cleaned sets of panels over a
20-day period. Note all strings were equally soiled before twice-weekly cleaning commenced at the
start of the time period (28 March 2019).
16. Energies 2019, 12, 2923 16 of 21
The effect of the water cleaning system can also be seen from a visual comparison given in
Figure 17, where the side-by-side string S-III (reference) and S-IV (water-cleaned) can be seen in a
photo taken in the evening when the water cleaning programme was commenced for the first time
on 8 March. The image clearly shows that string S-III was covered by a considerable amount of dust,
whereas string S-IV was significantly clearer after water cleaning.
Figure 16. Difference in array performance between cleaned and non-cleaned sets of panels over a 20-
day period. Note all strings were equally soiled before twice-weekly cleaning commenced at the start
of the time period (28 March 2019).
The effect of the water cleaning system can also be seen from a visual comparison given in Figure
17, where the side-by-side string S-III (reference) and S-IV (water-cleaned) can be seen in a photo
taken in the evening when the water cleaning programme was commenced for the first time on 8
March. The image clearly shows that string S-III was covered by a considerable amount of dust,
whereas string S-IV was significantly clearer after water cleaning.
Figure 17. Visual observation of water-cleaned string (S-VI) versus reference string (S-IV) after first
water cleaning programme commenced.
Figure 16 shows the mean power output for 20 days from each string between 08:00 and 09:00
(local time). The figure indicates that before commencing cleaning, the monitored sets of strings (S-V
and S-VIII) show similar power output. After water-based cleaning began, there is a clear improvement
in the power output from the water-cleaned strings (S-IV, S-VI and S-VII). For the time period selected,
the output of cleaned strings was 177 W (on average) compared to 140 W from that of the uncleaned
strings (string S-II, S-III, S-V and S-VIII, see Figure 6). This represents around 27% more power from
the cleaned strings (SD = 4.4%) over the 20 days compared to the non-cleaned strings.
In Figure 16, the variation of the average solar irradiance was depicted for the same period.
The results show that it varied significantly from 105 W/m2 (26 March) to 433 W/m2 (17 March) and the
output from the PV strings strongly correlated with such variations, causing several power production
drops, such as on 22 February and 28 March 2019 (Figure 16).
The 08:00 and 09:00 time slot was chosen for analysis, as the battery was never fully charged
during this period. The state of charge of the battery in the morning is always depleted due to the
air conditioning and other load utilisation during the night. After sunrise, the MPPT ensures that all
the strings provide the maximum possible power until the battery state-of-charge recovers to 100%.
Consequently, the performance of the strings early in the morning, before the battery has recovered,
provides the fairest comparison between cleaned and non-cleaned strings.
3.3. Net Loss of Water During Cleaning
In addition to minimising the loss in PV module performance due to soiling, the other research
aim is to minimise the net use of cleaning water. Therefore, it is important to determine accurately the
volume of water lost during water-based cleaning modes. In order to achieve this, the filling curve for
the water tank was determined by first calibrating the depth (pressure) sensor and then filling the tank
(cylinder shape but horizontally-fitted, see Figure 4) from empty, while simultaneously recording the
counts from the water meter and the depth given by the pressure sensor. The resulting filling curve is
17. Energies 2019, 12, 2923 17 of 21
shown in Figure 18 along with a cubic curve-fit to the depth d. A cubic fit was used due to the point of
inflection at mid-depth.
In addition to minimising the loss in PV module performance due to soiling, the other research
aim is to minimise the net use of cleaning water. Therefore, it is important to determine accurately
the volume of water lost during water-based cleaning modes. In order to achieve this, the filling curve
for the water tank was determined by first calibrating the depth (pressure) sensor and then filling the
tank (cylinder shape but horizontally-fitted, see Figure 4) from empty, while simultaneously
recording the counts from the water meter and the depth given by the pressure sensor. The resulting
filling curve is shown in Figure 18 along with a cubic curve-fit to the depth d. A cubic fit was used
due to the point of inflection at mid-depth.
Figure 18. Filling curve for 2000 litre horizontal water tank.
The curve was fitted using the Nonlinear Least Squares (NLS) package in R programme [27,28],
giving the four fitted parameters significant at the 0.1% level on 54 degrees of freedom. The four fitted
Figure 18. Filling curve for 2000 L horizontal water tank.
The curve was fitted using the Nonlinear Least Squares (NLS) package in R programme [27,28],
giving the four fitted parameters significant at the 0.1% level on 54 degrees of freedom. The four fitted
coefficients (k0, k1, k2, k3) were −0.0802, 1.259, 1.692, −1.211, respectively. The curve is now used to
calculate volume losses (and gains in the case of rainfall) as a function of depth change. For example, the
losses of cleaning water from the different nozzle configurations can be directly calculated. Figure 19
shows the water lost due to a 30 s deluge of water of module B4 followed immediately by a 30 s deluge
of module C4 (Figure 6). The figure indicates that the final loss was approximately 9 L.
Energies 2019, 12, x FOR PEER REVIEW 18 of 22
coefficients (k0, k1, k2, k3) were −0.0802, 1.259, 1.692, −1.211, respectively. The curve is now used to
calculate volume losses (and gains in the case of rainfall) as a function of depth change. For example,
the losses of cleaning water from the different nozzle configurations can be directly calculated. Figure
19 shows the water lost due to a 30 s deluge of water of module B4 followed immediately by a 30 s
deluge of module C4 (Figure 6). The figure indicates that the final loss was approximately 9 litres.
Figure 19. Loss of cleaning water from the water-based system due to 60 s deluge for modules B4 and
C4 (Figure 6).
3.4. Economic Analysis
The success or otherwise of cleaning systems for PV carports will depend on whether, and how
quickly, they can pay back the extra investment required for the system through reduced loss of
electrical generation income due to soiling. Here we present a simple yet reasonable analysis of a 100
kW production system, grid-connected, with water-based cleaning on all modules.
Figure 19. Loss of cleaning water from the water-based system due to 60 s deluge for modules B4 and
C4 (Figure 6).
18. Energies 2019, 12, 2923 18 of 21
3.4. Economic Analysis
The success or otherwise of cleaning systems for PV carports will depend on whether, and how
quickly, they can pay back the extra investment required for the system through reduced loss of
electrical generation income due to soiling. Here we present a simple yet reasonable analysis of a
100 kW production system, grid-connected, with water-based cleaning on all modules.
The rate at which the cleaning system pays back the investment required is clearly very dependent
on the value of electricity exported to the grid. Here we have assumed that the export tariff will be
equivalent to the commercial import rate [29]. This is reasonable as it is likely that carport PV arrays will
be installed in extensive car parks of large buildings, and the generation from the system will directly
displace some of the air-conditioning load from the building or buildings. In addition, the cost of water
was taken as the standard commercial rate in the Jeddah area [29]. The reduction in efficiency of the
soiled panels was taken as 20% based on the results presented in Section 3.2 and the rate of water loss
per module per cleaning event of 5 L (based on Section 3.3). Both of these are likely to be conservative
estimates, as optimization of the system is yet to be carried out. As cumulative installed capacity increases,
it would be expected that installed costs would decrease, typically along an “experience curve” [30].
The parameter b for the experience curve was taken as a conservative 0.9, implying a 10% decrease in
installed cost for each doubling of production. The base unit of production was a notional 100 kW system
and the present value calculations made at four cumulative levels of experience, 100 kW, 1 MW, 10 MW,
and 100 MW. Installed equipment costs for the 100 kW unit were estimated from the experience of the
6 kWp system described in this article with the discount rate assumed to be 10%. More details of the
assumptions made for the analysis are provided in Table A1 in Appendix A.
Table 2 shows that for the case of the first 100 kW unit, the net present value (NPV) is positive
after five years. However, after ten units, this reduces to four years; after 100 units, three years and
after 1000 units, two years. This would imply that the water-based PV module cleaning system is
worth the investment providing it is installed at scale.
Table 2. Net present value analysis for the cleaning system of a notional 100 kW PV carport at different
points on the experience curve. All values in USD. Please see Appendix A for more details of the
assumptions made for the analysis.
Variable (USD) First Unit (100 kW) After 10 Units After 100 Units After 1000 Units
Initial investment 27,200 19,168 13,507 9518
Running cost 1220 1059 946 866
Additional income from export 8503 8503 8503 8503
NPV after 2 years −14,560 −6249 −392 3735
NPV after 3 years −9088 −656 5286 9473
NPV after 4 years −4114 4428 10,447 14,689
NPV after 5 years 408 9050 15,139 19,431
4. Summary and Future Work
This work reported on the design philosophy for an automated cleaning system for PV modules
subjected to the harsh desert environment of Saudi Arabia. The system is based on multiple cleaning
mechanisms including vibration, air and water, and some combinations of these. The system was
equipped to collect the cleaning water for subsequent reuse and installed on a carport canopy in the
campus of King Abdulaziz University, Jeddah, Saudi Arabia. The overall system was established as a
testbed to investigate the performance of various cleaning systems that were designed to remove dust
from solar PV modules.
To allow performance analysis of PV power output, eight individually instrumented PV strings
in the array were monitored with multiple cleaning methods tested during the same time period.
The effectiveness of each cleaning mode was measured in terms of the amount of power produced in
comparison with reference strings (control) of PV modules. The results indicate that for water-cleaning
19. Energies 2019, 12, 2923 19 of 21
mode only, string power output increased by an average of 27% (Figure 16) compared to non-cleaned,
but otherwise identical, strings for the same period of time.
The vibration cleaning mode was not observed to have a significant effect on the performance
degradation due to soiling versus the reference panels. The compressed air was not able to be fully
trialled due to the use of the temporary air compressor, which did not provide enough continuous
air capacity to undertake longer testing. A new air system is currently being designed with further
cleaning mode combinations, which will be tested in the future.
Overall, the testbed has provided a new approach to testing a combination of cleaning solutions
in the field. Its aim is to identify appropriate combination of cleaning modes to inform the ongoing
expansion of PV projects currently being built or planned for the future in Saudi Arabia. These
studies will provide the evidence needed to support yield optimisation in large PV arrays through
quantifying the efficiency improvements from the cleaning approaches. Furthermore, the testbed has
the capacity for additional cleaning units to be added, allowing four more cleaning methods to be
tested. These include using blades or PV module surface coatings, integrated pipework and air jets,
and new vibration systems. The testbed is providing opportunities for studies of optimised cleaning
approaches of solar PV arrays and comparing their performance under the Saudi/Middle Eastern
weather conditions, such as sandstorms and humidity. The configuration of the setup and parameters
used for the system will be further tested and optimised to identify approaches that would improve
dust removal effectiveness and efficiency.
To extend the scope of cleaning mechanisms, more cleaning methods will be tested on the developed
solar system to conduct further assessments. This would include (1) combination of vibration and
pressurized air, (2) electrostatic dust removal systems, and (3) nanofilm coating. The feasibility of
installing additional monitoring equipment, such as high-frequency wind velocity monitoring and
visual inspection system to quantify and compare dust soiling, will also be investigated.
Author Contributions: The authors contributed equally to the paper including design, implementation, data
gathering, modelling, analysis, and discussion of the outcomes. More specifically, A.S.A. led the KSA side of the
research project, obtained essential research data, KAU campus analysis, permissions, coordination of the local
contractors and budgeting and design; A.S.B. led the UK side of the project and managed the coordination and the
overall design of the project including jointly supervising the various stages of project development, installation
and analysis; L.S.B. led the design and configuration of data collection and control systems; Y.W. undertook
cleaning system design and data analysis. All authors contributed to the writing, proof reading, and revision of
the manuscript.
Funding: This work is part of the activities of King Salman bin Abdulaziz Chair for Energy research at King
Abdulaziz University (KAU), KSA. Funding for this collaborative project was provided by King Salman bin
Abdulaziz Chair for Energy research, the Vice Presidency for Projects at King Abdulaziz University, and the Energy
and Climate Change Division and the Sustainable Energy Research Group at the University of Southampton, UK,
(www.energy.soton.ac.uk).
Acknowledgments: The authors would like to acknowledge the contribution of the UK industrial partners
represented by David Marriott and his team at Clarke Construction Essex Limited, and David Saunders from
Seriatim Ltd and to thank them for their dedication and effort during the design, testing, construction and
commissioning stages of the solar PV carport and its various systems.
Conflicts of Interest: The authors declare no conflict of interest.
Appendix A
Table A1. Economic analysis parameters used in Section 3.4.
Parameters Unit Value
Basic Parameters
Discount rate percent 10.0
Cleaned efficiency percent 12.0
Drop in efficiency due to soiling percent 20.0
Cleaning events per module per week - 3
20. Energies 2019, 12, 2923 20 of 21
Table A1. Cont.
Parameters Unit Value
Basic Parameters
Export tariff USD/kWh 0.049
Average irradiance (in plane) kWh/m2/day 6.70
Loss of water per cleaning event L/module 5.0
Annual maintenance cost (% of equipment cost) Percent 2.0
Installed capacity kWp 100.0
Power consumption per cleaning event kWh/module 0.010
Module capacity Wp 275
Module area m2 1.64
Experience curve parameter b - 0.9
Equipment Costs
Pump USD 1000
Water tank USD 2000
Filters USD 1000
Control system USD 5000
Pipework, fittings and gutter USD/module 50.00
Consumables
Make-up water USD/L 0.00228
Power consumption USD/kWh 0.0486
Calculated Values
Number of modules - 364
Water use per year L 283,920
Power consumed (at night) kWh 568
Increase in generation kWh 174,962
Extra generation income USD 8503
Water cost USD 649
Power cost USD 28
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