Investigation of seasonal dust accumulation intensity at four PV power plants surrounded by different types of agricultural areas in a hot and humid climate

Most PV power plants encounter soiling problems that reduce the performance of the PV system by up to 3% per month in Thailand, requiring costly maintenance interventions. Dust or soiling accumulation is a complex phenomenon that depends on site-specific factors such as humidity, wind speed and direction, ambient temperature, season, dust source, and activities in the surrounding area. Therefore, understanding the patterns and factors that influence dust accumulation is important for determining effective dust mitigation strategies. This research investigates the intensity of dust accumulation throughout the year in four PV power plants, which are surrounded by different types of agricultural areas (rice, cassava, corn, and sugarcane) and rock blast mines. The pieces of glass were exposed to accumulating dust at PV power plant for one year. The dust intensity was investigated using microscope images taken every 2-week, and then the area fraction of the dust was analyzed with the ImageJ program. In this study included two types of dust accumulation: type A, which focused on dust accumulation throughout the year, and type B, which examined new dust accumulation according to different seasons.
The results show that the highest dust accumulation in different areas occurred as follows: PV power plants surrounded by rock blast mines had the highest area fraction at 27.84% (in January), followed by PV power plants surrounded by cassava and rice fields, with the highest area fraction being 25.5% (in February). The PV power plant surrounded by rice fields exclusively had an area fraction of dust up to 19.21% during March. However, during the dry season, dust accumulation is not continuous. There is a decrease in the accumulation rate due to reduced dust accumulation or cleaning by rain and wind. During the rainy season, from May to September, the dust accumulation rate is very low, at approximately ±0.01% per day. Moreover, the monthly average area fraction rate of all PV power plants was highest in January at 0.47% per day. It decreased to 0.42% per day in December, 0.33% per day in November, 0.32% per day in February, 0.21% per day in March, 0.11% per day in April, and 0.09% per day in October, as shown in Figure 1.
Additionally, by season, the rate of dust accumulation is highest in winter, followed by summer, with the least or no accumulation occurring in the rainy season, as shown in Figure 2. Moreover, the comparison of type A and type B rate of dust accumulation found a higher accumulation rate with seasonal change compared to dust accumulation through year. This means that dust accumulates more on clean surfaces than on unclean surfaces, but this is not beneficial for electricity product in PV systems. Implementing a proper cleaning schedule will benefit PV power plant investors.