Effects of dust accumulation on performances of thermal and photovoltaic flat-plate collectors

The performances of one photovoltaic and two thermal panels during several months of outdoor exposure have been measured. For the photovoltaic panel, the average degradation rate of the efficiency was 7% per month, whereas, for the thermal panels, the average degradation rate on the optical efficiency ranged from 2·8% to 7% per month for this maritime-desert-subzone type of environment.