Time-of-day and Exposure Influences on PV Soiling

Soiling of PV modules is influenced by environmental parameters., both instantly and cumulatively over time. Field measurement of dust accumulation at a minute time-scale, using an outdoor soiling microscope, was used to study the effect of time-of-day and exposure period on soiling of a surrogate glass coupon in Doha., Qatar. It was found that dust accumulation was much greater at night than during the day, principally because of lower nocturnal wind speed and higher humidity. Also, detachment of dust particles from the surface decreased markedly as exposure time increased., possibly due to cementation by moisture. The results suggest that tilting PV modules at night may be a simple yet potent way to decrease their soiling in suitable locations.