Modeling of Soiling Derating Factor in Determining Photovoltaic Outputs

The study of the effect of soiling on photovoltaic (PV) system performance is a crucial issue judging from numerous research publications. The reduction in the PV system performance is because of soiling that differs from one climatic region to another. In this research, the power losses due to soiling of the PV systems in Malaysia based on the calculation of a dirt derating factor (fdirt) were determined. A new mathematical model to correlate fdirt and the PV module area was developed based on the regression analysis from a site data location. The findings indicate that the effect of soiling reduces the PV systems output power at an average of 26.22% at Setiu over a period of 12 months. From this study also, a new mathematical model was created for fdirt forecasting in the research site. Uniquely, this mathematical model can do the prediction by only known PV module area or size as the independent variable, much simpler than using the multivariables equation.