Investigation of soiling effects for east/west vertical bifacial and north/south tilted monofacial photovoltaic farms

Abstract

The output energy produced by the photovoltaic system strongly depends upon the amount of solar radiation harvested by the photovoltaic panels. Varying the tilt of photovoltaic panels at the optimal angle and/or cleaning the photovoltaic panels at regular intervals are some of the techniques that could enhance the photovoltaic system performance albeit at the cost of increased labor and water budget. Here, we explore a farm-level study to investigate the effect of different tilt angle adjustment schedules on the performance of conventional north/south ( $N/S$ ) tilted monofacial photovoltaic farms. We further compare the performance of optimally tilted $N/S$ photovoltaic farms with that of east/west ( $E/W$ ) faced vertical bifacial photovoltaic farms for various dry periods for Lahore, Pakistan. We show that for a dry period of one month, the performance of $N/S$ tilted farm is decreased by $\sim$ 40 kWh/m² as compared to that for $E/W$ farm that exhibits a performance degradation of $\sim$ 3 kWh/m². Further, $N/S$ farm performs better than $E/W$ vertical farm if the cleaning is performed on (or before) fortnightly basis. Further, if cleaning is delayed for one month, then $E/W$ vertical farm performs better than $N/S$ tilted farm. The results presented in this work are beneficial for the development of $E/W$ faced vertical bifacial farm in dusty climates and regions with scarce water supply.