Dust accumulation effects on efficiency of solar PV modules for off grid purpose: A case study of Kathmandu

The future of the world lies with renewable energy resources and solar energy is one such type of clean and sustainable energy resource. Solar PV modules are exposed to outdoor environments where dust accumulation is a prime degrading factor. Soiling and its effect on performance of solar modules are generally of high concern for regions with a high deposition of dust and low frequency and less intensity of rain. But some areas with abundant rainfall may also suffer from high dust deposition in the dry season. Kathmandu, with its peculiar environment conditions, suffers high air pollution and minimum rainfall during the dry winter. In this study, the effect of dust on PV modules is investigated with respect to dust deposition density and meteorological variables for Kathmandu with the objective to calculate a regression equation describing efficiency loss. Outdoor installation of experimental setup showed that during the study period of 5 months, the efficiency of dusty solar module left to natural dust deposition phenomena decreases by 29.76% with respect to the module which was cleaned on daily basis. Dust deposition density on the PV module accounted to 9.6711 g/m2 over the study period. The research also showed that dust accumulation is highly concentrated at the bottom of the PV modules having a high risk of hot spots which could eventually lead to permanent module damage.