Performance Reduction of PV Systems by Dust Deposition

The deposition of dust on photovoltaic modules is of importance as parameter for economic analysis and life cycle assessments to evaluate this kind of technology for generation of electricity. Even though during the last two decades several photovoltaic plants were implemented, only a few studies about this issue were performed. This work tries to estimate the annual loss of generated energy caused by dust deposition on PV modules based on an experimental setup of a grid connected PV plant, monitoring of solar irradiation, onsite determination of dust deposition rate, and processing climatic data to obtain information about the frequency of rainfall occurrence. In Mexico City, air pollution with suspended particulate matter with diameter below 10 μm (PM 10) is almost permanently over 50 μg m-3. This contamination contributed to an average dust deposition rate of 65 g m-2d-1 on horizontal surfaces. Dust accumulation during rainless periods of more than 60 days can reduce production of PV systems up to 15%. With the capacity of natural cleaning by rainfalls, annual loss of production is estimated to be 3.6%.