The Impact of Dust on PV Module Temperature and Performance

A team of international researchers has explored how dust buildup affects solar panel efficiency in two distinct climatic zones of Pakistan. They meticulously measured dust accumulation on the panels, examining their composition and particle sizes.

In Islamabad, the capital of Pakistan, they installed a setup on a building's rooftop. Islamabad enjoys a clean, warm climate with a yearly average temperature of 20.3°C and regular rainfall, which helps keep solar panels clean. Conversely, in Bahawalpur, a southern city situated in a desert area, the climate is dry with little rainfall but frequent wind and dust storms, with an average temperature of 26.1°C.

The experiment used 40 W polycrystalline panels, including reference panels that were routinely cleaned. All panels were south-facing, fixed at a 34-degree tilt on metal stands.

The researchers gathered data on solar radiation and the voltage and current from each panel. They also attached glass sheets to the modules to collect and analyze dust.

After six weeks, they observed a notable drop in efficiency due to varying dust densities in Islamabad and Bahawalpur. The dust accumulation was 6.388 g/m2 (daily average 0.152 g/m2) in Islamabad and 10.254 g/m2 (daily average 0.244 g/m2) in Bahawalpur. SEM analysis revealed that dust particles in both cities varied in size, shape, and arrangement.

The dust from Islamabad mainly consisted of carbon (55.8%), followed by oxygen, silicon, and calcium. Other elements like aluminum, iron, potassium, magnesium, and sodium were in smaller amounts. In Bahawalpur, oxygen was the predominant component (46.9%), with carbon, silicon, and aluminum also significantly present.

Comparing clean and dusty modules, the researchers found a 15.08% power output reduction in Islamabad and a 25.42% reduction in Bahawalpur.

They concluded that the decreased output was due to the shielding effect of dust blocking sunlight and the "dust-temperature" phenomenon. This effect is caused by dust-altering heat transfer on the panels, leading to hotspots.