Researchers studied the effect of dust accumulation on the performance of photovoltaic systems in two climate regions of Pakistan. Academics from Pakistan’s National University of Sciences and Technology (NUST), the Islamia University of Bahawalpur, and the University of Warwick in the United Kingdom took part in the research, setting up one installation on the roof of a building in Pakistan’s capital, Islamabad, and another in the southern city of Bahawalpur. They quantified the precise amount of dust density on the panels and analyzed the composition and size of the particles.
“Islamabad’s climate is clean, pleasant, and warm, with an average annual temperature of 20,3°C. Even the driest month receives plenty of rainfall, which helps clean the photovoltaic modules,” they said. “Bahawalpur is located in a desert region with a dry climate and almost no rainfall, but frequent winds and dust storms, and an average annual temperature of 26,1°C.”
“Islamabad’s climate is clean, pleasant, and warm, with an average annual temperature of 20,3°C. Even the driest month receives plenty of rainfall, which helps clean the photovoltaic modules,” they said. “Bahawalpur is located in a desert region with a dry climate and almost no rainfall, but frequent winds and dust storms, and an average annual temperature of 26,1°C.”
The methodology
The setups consisted of 40 W polycrystalline modules and reference panels that were kept continuously clean. All modules were mounted on metal frames at a fixed tilt angle of 34 degrees, facing south. The research team collected data on global solar irradiance, as well as the voltage and current of each module. They attached sheets of glass to the photovoltaic modules to collect dust and analyze its properties. “After six weeks of exposure to the atmosphere, the dusty modules showed significantly lower performance, corresponding to the different dust densities in the two regions,” they noted.
The total dust accumulated in Islamabad was 6,388 g/m2, with a daily average of 0,152 g/m2. In Bahawalpur, the total dust accumulation was 10,254 g/m2, and the daily average was 0,244 g/m2. Scanning electron microscopy (SEM) showed that in both cities, the particles varied in size, had asymmetrical shapes, and were distributed unevenly.
“In the dust sample collected from Islamabad, carbon predominates, with a composition of 55,8%, followed by oxygen, silicon, and calcium, with compositions of 22,71%, 9,78%, and 3,85%, respectively. Aluminum, iron, potassium, magnesium, and sodium are also present in considerably smaller quantities,” the team reported. “In the dust sample collected from Bahawalpur, oxygen predominates, with a composition of 46,9%, followed by carbon, silicon, and aluminum, with compositions of 20,11%, 16,98%, and 4,26%, respectively.
Comparing the dirty and clean modules in each city, the researchers identified a reduction in output power of 15,08% in Islamabad and 25,42% in Bahawalpur. The researchers concluded that the reduced performance was due not only to dust reducing the absorption of sunlight through the so-called shielding effect, but also to the dust temperature effect. The latter occurs because dust on the photovoltaic module changes the mode of heat transfer and leads to the formation of hot spots.
Source: energy mag
“In the dust sample collected from Islamabad, carbon predominates, with a composition of 55,8%, followed by oxygen, silicon, and calcium, with compositions of 22,71%, 9,78%, and 3,85%, respectively. Aluminum, iron, potassium, magnesium, and sodium are also present in considerably smaller quantities,” the team reported. “In the dust sample collected from Bahawalpur, oxygen predominates, with a composition of 46,9%, followed by carbon, silicon, and aluminum, with compositions of 20,11%, 16,98%, and 4,26%, respectively.
Comparing the dirty and clean modules in each city, the researchers identified a reduction in output power of 15,08% in Islamabad and 25,42% in Bahawalpur. The researchers concluded that the reduced performance was due not only to dust reducing the absorption of sunlight through the so-called shielding effect, but also to the dust temperature effect. The latter occurs because dust on the photovoltaic module changes the mode of heat transfer and leads to the formation of hot spots.
Source: energy mag
