Scientists in Germany have collected dust from Qatar, Morocco and Thailand to analyze the impact on the performance of uncoated solar glass and uncoated PV mini-modules. Their analysis has shown that dust coverage could range from 4% to 60%.
A research team led by scientists from Germany’s Anhalt University of Applied Sciences has conducted a study of the impact of different types of dust on solar transmittance and PV performance.
Specifically, they analyzed and tested dust samples from urban areas of Qatar and Morocco, a rice field and a biofuel refinery plant in Thailand (Thai 297 dust), as well as cassava and corn farms from the same country (Thai 274 dust).
“The results of this work provide a wealth of helpful information and findings on the optical, electrical, and microscopic characterization of soiling,” said the scientists. “In addition, this comprehensive study provides valuable insights into the region-specific effects of the dust properties that occur. In summary, extensive correlation analyses will show the differences between the analysis methods.”
According to the analysis of the different dust samples, all contained quartz (SiO2) and calcite (CaCO3) fractions in varying quantities. The dust from Morocco and Thai 297 have comparable quartz contents of 43% and 35%, respectively; Qatari dust has 3%; and Thai 274 dust has 85%. The calcite content of the Qatari dust is the highest, at 59%. The Qatari and Moroccan dust samples have a water content of approximately 3%, Thai 274 dust has 3.8%, and Thai 297 dust contains 6.7%.
The researchers used two sample groups – uncoated solar glass and uncoated PV mini-modules. The uncoated solar glasses consisted of 12 samples, and the PV mini-modules consisted of four modules, with each test using one type of dust for soiling.
The samples were cleaned with water between the tests and were then used under constant ambient conditions at 60% relative humidity (RH) and a temperature of 22 C during dust deposition. A light dew cycle exposed each sample to dew point conditions. The subsequent a 40 C heating treatment initiated a cementation process that bound the dust to the surface.
Both the mini modules and the uncoated solar glasses were tested under a dust coverage of 4% to 60%. Qatari dust showed the lowest slope in transmission loss, with a surface coverage of 0.51. In contrast, Thai 297 shows the strongest transmission loss, with a surface coverage of 0.60. The transmittance loss of the dust from Morocco and Thai 274 shows an almost identical slope of 0.53.
“The short-circuit losses as a function of surface coverage have the expected linear trend,” said the scientists. “However, the measured slopes are lower than the calculated slope. Nevertheless, ranking is equivalent to the observations. Thai 297 shows the strongest slope of Isc loss of 0.56. Qatar dust shows the lowest slope, 0.40, Morocco dust shows 0.42, and Thai 274 shows 0.43.”
The research team said its findings could be used to refine mathematical models aimed at optimizing the efficiency and performance of photovoltaic systems in arid and semiarid regions.
Their word was presented in “Impact of Different Types of Dust on Solar Glass Transmittance and PV Module Performance,” published in Progress in Photovoltaics. Scientists from Germany’s Fraunhofer Center for Silicon Photovoltaics (CSP), Fraunhofer Institute for Microstructure and Systems (IMWS), and Thailand’s King Mongkut’s University of Technology Thonburi have participated in the study.