A comparative evaluation of different PV soiling estimation models using experimental investigations

Dust accumulation on cover facets of PV panels has a detrimental effect on the performance characteristics. In the present study, a thorough investigation on the impact of dust mass accumulation on the surface of PV panels has been presented by exposing PV modules and glass coupons to natural soiling. The site-specific nature of soiling phenomenon has been analyzed by testing 12 different models classified under three categories at study location. Transmittance loss models based on natural soiling experiments showed errors <2 % while the errors associated with PM deposition-based models ranged from 4 to 14 % and it was found that these models are sensitive to cleaning episodes. The errors associated with empirical models which relate soiling with different environmental parameters through regression were as high as 40-93 % and thus, cannot be used at different sites. The major finding of the study helped to conclude that the use of averaged input parameters to model soiling losses neglect the impact of short-term events (wind gusts and drizzle) and thus, compromise the accuracy of soiling predictions.