Investigation of soiling impact on PV modules performance in semi-arid and hyper-arid climates in Morocco.

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]