Seasonal photovoltaic soiling: Analysis of size and composition of deposited particulate matter

• Published in: Solar energy Vol. 227; pp. 44 - 55
• Main Authors: Valerino, Michael, Ratnaparkhi, Aniket, Ghoroi, Chinmay, Bergin, Mike
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.10.2021; Pergamon Press Inc
• Subjects: Caking; Cementation; Chemical precipitation; Composition; Dust; Dust composition; Dust deposition; Energy; Energy dissipation; Energy loss; Environmental monitoring; Lamps; Low cost; Monitoring; Monsoons; Nonuniformity; Particle size distribution; Particulate emissions; Particulate matter; Photovoltaic; Photovoltaics; Rainfall; Renewable energy; Salts; Seasonal variations; Size distribution; Soiling; Soils; Solar energy; Solar panel; Solar soiling; Dust deposition; Photovoltaic; Soiling; Solar soiling; Solar panel; Dust composition
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2021.08.080

[Display omitted] •Soiling rates are half a percent loss per day but negligible during monsoon.•Monsoon rains cleaned off most large particles but there was a buildup of PM2.5.•Majority of the composition was crustal dust and did not have a seasonal difference.•Rain and humidity caused milli-scale nonuniformity and carbonaceous caking.•Fungal growth occurred after 3 weeks. Photovoltaic soiling - energy loss due to dust and particulate matter (PM) deposition - remains a top concern for global renewable energy generation. To minimize energy losses, the seasonality of soiling needs to be understood. This comprehensive study took place in Gandhinagar India and combined soiling monitoring (using a Campbell Scientific soiling station and a new, low-cost sensor called the Low-cost Alternative to Monitoring Photovoltaic Soiling, or LAMPS station) for all of 2019 with 3-week sampling cycles to analyze size distribution and composition. The LAMPS station has been found to monitor soiling to an accuracy of within 1.5% soiling. Soiling rates were found to be 0.45 ± 0.10% day−1 during dry periods and negligible during the monsoon. The monsoon rains dramatically shifted size distribution with a 90% reduction of deposited > PM10 mass, but more than twice the mass of deposited PM2.5 particles. Rain and humidity also lead to non-uniformity in mass loading over the scale of millimeters, deemed milli-scale non-uniformity (MSNU). Composition was found to be >95% crustal dust and there was no difference in composition seasonally. There was also no compositional difference between sizes of particles larger than PM2.5. Moisture led to a variety of cementation products deriving from reactions with water soluble gases as well as precipitation reactions all taking place within droplets on the surface. The most prevalent cementation effect was caking masses high in carbon and salts. Fungal growth was seen to be growing, and spore producing, after just 3-weeks.