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Many solutions have been developed regarding the cleaning of solar reflectors involved in solar energy systems to improve their performance. Most of these solutions are based on the use of water in cleaning operations which does not support the sustainable program of countries suffering from water scarcity. The present paper has proposed and investigated an innovative approach regarding cleaning of solar aluminum mirrors with and without the use of water. The comparison of the performance of both solutions has led to similar results in terms of cleaning efficiency of around 96.27% and 96.03% for wet and dry cleaning respectively. A solar power plant is simulated to evaluate the energy production and the cost of the kWh which has shown that the annual energy production was obtained with a deviation of 0.05%. Furthermore, the cost of the kWh produced by the solar plant was not clearly influenced by the type of the cleaning adopted with a difference of 0.0001$ and a deviation of about 0.07%. In this respect, the use of dry cleaning has allowed the preservation of a consistent amount of water of 73 833 m3 per year. [ABSTRACT FROM AUTHOR]

• First assessment of anti-soiling coating performance for CSP in arid region. • Comparison of cleaning and soiling mitigation by the studied coating. • Size analysis of particles deposited on the coated and uncoated mirrors surface. • Cleanliness gain achieved 7 pp manifesting the positive performance of the coating. • Significant reduction of particles deposited on the coated mirrors by 75.5%. Soiling of solar reflectors is a great challenge in regions with high aerosol concentrations and little rain such as arid and semi-arid climates. Actually, cleaning operations of the solar field in the CSP plants take a crucial part in the O&M costs. Coating is among the preventive mitigation methods, aiming to repel the dust from the solar collector's surface. This approach based on the treatment of surface properties, has seen a great technological development in the last few years. In this paper, the performance of an anti-soiling coating applied on several sets of mirror samples has been evaluated in real outdoor conditions on different heights at the arid site in Ouarzazate. Systematic measurements of the cleanliness factor during a year of exposure have been analyzed, taking into account the nature of the surrounding environment. Through this work, many findings have been obtained, which are considered very promising for the studied anti-soiling coating. The coated mirrors have shown a positive performance during the whole period of exposure, where the maximum cleanliness gain has achieved 7 pp. It was found that a maximum soiling rate of 2.54 pp/day was attributed to uncoated samples. This coating has significantly reduced the number of soiling particles deposited on the mirrors surface by 75.5%. This result is considered very valuable for the anti-soiling coating, enhancing its application in sites characterized by high levels of soiling. [ABSTRACT FROM AUTHOR]

This paper presents a continuity of experimental measurements of soiling over a period of two years of exposure in Rabat-Morocco which is characterized by semi-arid climate (according to the aridity index of De Martonne). Based on an appropriate approach, the soiling rate has been calculated directly via the transmitted and the received irradiance and it has given the average annual soiling rate of 4%. The energy production loss has been calculated considering the effect of soiling and it has reached 2 Wh/W p.day during the dry period. The approach presented in this paper is based on using solar front-glass which is quite efficient, since it presents the advantage of limiting losses that can occur. Strongly depending on the climatic conditions, the soiling ratio has been also investigated with rainfall, wind speed and wind direction in both Rabat (semi-arid climate) and Errachidia (hyper-arid climate). Through this study, several hypotheses have been deduced for the definition of the appropriate type of cleaning of photovoltaic installations; in semi-arid climate (Rabat), humid cleaning is highly required with limited frequency, while in hyper-arid climate (Errachidia) a frequent dry cleaning can be well sufficient. • Average annual soiling rate has been determined based on a solar glass exposed in Rabat, Morocco. • The energy production of photovoltaic modules has been calculated with the effect of soiling. • Humid cleaning and dry cleaning have been defined respectively for the semi-arid and hyper-arid climates. [ABSTRACT FROM AUTHOR]