Angular dependencies of soiling loss on photovoltaic performance in Nigeria

Abstract

Photovoltaic performance is significantly affected by soiling on its covering surface, which is strongly influenced by its tilt angle. This raises concern for the potential investor, policymakers, engineers, and local populace in regions where the soiling rate and its potential threats remain relatively unexplored. This study investigated the effect of dust accumulation on PV, considering the influence of tilt angle using a low-cost in-house developed soiling station exposed in a region with high solar energy potential, low PV penetration and high energy demand. Low iron glass coupons were exposed monthly, seasonally, and annually, each in three-position (horizontal, 45° tilt, and vertical plane). The result revealed that the highest reduction in transmittance was recorded on a horizontally positioned coupon with a significant decrease of about 88%. In comparison, the lowest transmittance reduction of an exposed coupon was recorded from a vertical position with about a 1% reduction. These transmittance reductions were further illustrated using PV power output reduction. Accumulated dust density on each coupon was recorded, with the lowest of about 0.2 g/m2 and the highest of 12.56 g/m2. It was concluded that horizontally positioned coupons accumulated more dust and gradually decreased as the angle tilted towards the vertical position. This research work highlights cycles of high soiling in the region; the information could be used to predict soiling events that could provide maintenance guidance where optimum scheduling for preventing and restoring PV performance can be achieved.