Comparative Investigations of the Effects of Soiling of PV Modules and Systems in Tropical, Subtropical, and Semi-Arid Climate Zones in Brazil

Brasil's principally southern-hemisphere geographic location represents interesting, complex, and comparative opportunities for soiling studies, encompassing sub-tropical, tropical, and Semi-Arid climate zones. This paper summarizes our methodology, with results quantifying the soiling ratios (SRatio) and soiling rates (SRate) for different photovoltaic (PV) technologies installed in diverse climate-zones in Brazil (based on our climate-zone mapping). Specifically, these analytic procedures are validated for soiling monitoring stations composed of both mc-Si and thin-film CdTe modules. A mathematical model determined the SRatio and SRate for each site (in compliance with the IEC-61324-1 monitoring standard). The results specify: (1) a mean SRatio for the period of analysis for Belo Horizonte (-19.92° N, Lo-43.99° W), Porto Alegre (-30.05° N, -51.17° W), and Brotas de Macaúbas (12.0011° S, 42.6303° W). From the SRatio characteristics, (2) the dry-season data were used to estimate the SRate through the Theil-Sem estimator. In addition, a method for analyzing energy production data of PV systems in order to extract the soiling rate is presented.