Scientists in China have analyzed the impact of soiling of PV module performance and have found that tilt angle has the greatest impact, followed by irradiance intensity and dust deposition density.
A research group led by scientists from China’s Northeast Electric Power University (NEEPU) has analyzed the performance of dusty PV modules under varying irradiance intensities and tilt angles. Furthermore, the group was able to create a model to predict maximum power loss based on irradiance intensity, tilt angle, and dust deposition density.
“This article introduces an innovative quadratic model with the maximum power loss rate as the dependent variable and irradiance intensity, tilt angle, and dust deposition density as independent variables,” the group said. “This model presents a significant advancement in understanding the interactions between dust deposition density, irradiance intensity, tilt angle, and maximum power output in PV systems, offering novel prospects and valuable methodologies for future research.”
The research had started by collecting dust from the PVs installed on the roof of NEEPU’s library. Using energy dispersive X-ray spectroscopy (EDS), the group has found the presence of the metallic elements iron (Fe), potassium (K), magnesium (Mg), aluminum (Al), calcium (Ca), titanium (Ti), and manganese (Mn), as well as the non-metallic elements carbon (C) and oxygen (O).
The setup
This dust was then mixed with 90% alcohol, to create different levels of depositions, with densities of 2.11 g/m2, 6.15 g/m2, and 10.13 g/m2. The dust mixture was then used to contaminate low-iron glass slides, which were ready for testing after the evaporation of alcohol. A xenon lamp was used to simulate different irradiance levels, namely of 1,000 W/m2, 900 W/m2, 800 W/m2, 700 W/m2, and 600 W/m2. Under those terms, the slides were tilted to either 0°, 15°, 30°, 45°, and 60°.
“The NEEPU is situated in the west-central region of Jilin City, China, which has a temperate continental monsoon climate. The laboratory indoor temperature is 20 C with no air circulation,” the academics noted. “Based on the instrument uncertainty, the preceding analysis yields a final uncertainty of 1.42%. This value is less than the 2% threshold set by engineering requirements, ensuring the accuracy of the experimental data.”
Per the results, dust deposition density has a more substantial impact on the average short-circuit current, average open-circuit voltage, and average maximum power under high irradiance levels, while its effect on average conversion efficiency is relatively weaker. The differences in those parameters among various other conditions are not significant.
The results
“When inclined at an angle of 60° with an irradiance of 1,000 W/m2, the relative short-circuit current, relative open-circuit voltage, relative maximum power, and relative conversion efficiency of a PV module with dust deposition density of 10.13 g/m2 are 62.3%, 89%, 61%, and 61%, respectively,” they found. “The relative short-circuit current, relative maximum power, and relative conversion efficiency increase with the irradiance while decreasing with the dust density and tilt angle. However, the relative open-circuit voltage decreases with the irradiance, dust density, and tilt angle.”
In addition, the academic team investigated different prediction models for maximum power loss and found a quadratic model that yielded the most accurate results. “It uses irradiation intensity, tilt angle, and dust deposition density as independent variables. The tilt angle has the most significant impact on the maximum power loss rate, followed by irradiance intensity, while the effect of dust deposition density is minimal,” they explained.
The results were presented in “Experimental study on the losses of dusty PV modules considering irradiance levels and tilt angles,” published in Energy Reports. The research was conducted by scientists from China’s Northeast Electric Power University and Datang Xinjiang Power Generation.