Environmental variables affecting solar photovoltaic energy generation in Morocco

The relative importance of environmental variables such as temperature, humidity, aerosols, clouds, and soiling are considered for inland and coastal regions in Morocco. Meteorological data from four sites in these regions (Marrakech, Ouarzazate, Oujda, Dakhla) are obtained from the Moroccan Directorate of National Meteorology, Meteonorm, and NASA AERONET to identify key environmental variables. Inland locations (Ouarzazate and Marrakech) have the highest global horizontal irradiation and ambient temperatures, resulting in the highest PV module temperatures. Percentage cloud coverage is low to moderate in all locations. Humidity and aerosol loading both peak in the summer season, whereas little precipitation is observed in this season, resulting in the potential for soiling accumulation in the summer in all locations. Estimates of the change in average monthly CdTe PV performance due to atmospheric variables are 0 to <;-6% for temperature, <;-1% to >1% for humidity, <;-0.1% to >0.1% for aerosols, 0 to <;-30% for clouds, and 0 to <;-3% for soiling with cleaning. Improvement in energy production for CdTe PV systems related to spectral shift is expected in most locations during the high humidity summer season. Change in power output as a function of module operating temperature is expected to be mostly within 6%, due to a low magnitude temperature coefficient for CdTe PV systems. When cleaning is necessary, dry brush cleaning methods limit soiling losses to less than a few percent per year without the use of water.