Quantifying Soiling Accumulation on Photovoltaic Modules Using Standard Testing Results

Abstract

Quantifying soiling accumulation on PV modules installed in the field can be determined by using standard laboratory testing results of short circuit current (Isc) and temperature coefficients. Soiling accumulation on PV modules affects to attenuate optical transmission to solar cells that is represented by reduction of Isc. Two c-Si PV modules were selected to present. The two PV modules were installed for a period of six months in outdoor conditions. The data of Isc were collected and then corrected different performances by using measurement results from the laboratory. All data were converted and normalized to data at STC condition by using Isc at STC and temperature coefficient of Isc. It is found that soiling accumulation was 8.8% at maximum values.  Increasing of soiling accumulation was 6.6% for a period of 42 days with no rainy day.  In this paper, it is found that the rate of increasing soiling accumulation on clean glass is higher than on soiled glass.  For the clean glass module, soiling accumulation was 0.71%, but the soiled glass was 0.31%, in the same 15-days period. The results of power loss, due to soiling accumulation, of a PV system installed beside the experiment were also reported. The system Power loss was 7.11%, but Isc reduction of module was 6.25% for a period of 34 days with no rainy day.