Laboratory calibration of a light scattering soiling sensor

Abstract

In this study, laboratory calibration of a commercial soiling sensor was carried out using Doha dust and the Arizona Test Dust A2 Fine. Soiling conditions ranging from 0.3 to 10 g m−2 in dust loading were created by aerosol deposition and sieve deposition methods using the two dust types. Transmission loss under each soiling condition was determined using a PV reference cell and a solar simulator, and the corresponding light scattering reading from the deposited dust was also obtained. A strong linear correlation with high reproducibility was found between the actual transmission loss and the light scattering reading. For both dust types, the actual transmission loss was approximately 2.4 times the soiling sensor’s reading with aerosol deposition and about 2.6 with sieve deposition. The difference in the correction factor may be attributed to the difference in dust property and the impact of the deposition method on the morphology of deposited dust. The calibration results can be directly applied to the commercial soiling sensor tested in this study for soiling caused by dusts similar to those used in this study. The findings also show that sieve deposition may be used in place of the more desirable aerosol deposition method for local dust calibration of soiling sensors, but it is necessary to evaluate the particle size distribution of the deposited dust for assessing the accuracy of the calibration result.