Monofacial and Bifacial Photovoltaics Systems with Uniaxial Solar Tracking

Abstract

The technology behind Bifacial Photovoltaic systems has existed for a long time but only recently gained popularity due to the increased surface area for the absorption of solar radiation by the rear-side of the bifacial Photovoltaic (PV) panel. The bifacial gain and output energy yield (kWh) is affected negatively by self-shading leading to non-uniformity in the absorbed irradiance. The purpose of this research is to simulate and investigate the effect of varying parameters including the elevation of a bifacial PV module from 0.5 m to 1.0 m with a step size of 0.1 m and its effect on the absorbed irradiance and subsequent output energy yield (kWh). Uniaxial solar tracking combined with varying the elevation is implemented by positioning the bifacial PV system in an East-West orientation with an azimuth angle of +90° (facing East); this follows the sun’s hourly elevation angle and path throughout the day. Three albedo of values 0.2 which represents grass, 0.6 which represents fresh white concrete and an ideal albedo of 0.99 is combined with the variation in elevation of the bifacial PV module and is further analysed and compared with a monofacial PV module. Simulation results from TracePro show that East-West tracking reduces the Incident angle closer to 0° which results in higher Flux (W) collected by the surface, except for time intervals at 8:00:00 AM and 18:00:00 PM where the sun is located furthest away from the model. The energy yield (kWh) of the bifacial PV panel first increases sharply from an elevation of 0.5 m to 0.8 m where a peak value of 4748.8 kWh is observed, followed by a drop in energy yield (kWh) at 0.9 m and saturation at 1.0 m; hence the elevation parameter of 0.8 m is determined to be the point of inflection. The BGE at 1 m has a significant value of 0.302 which translates to 30.2% in bifacial gain. The largest difference in energy yield (kWh) is observed to be 1114.55 kWh (30.67% increase) at 0.8 m; the bifacial PV module greatly outperforms the monofacial PV module at this elevation in the uniaxial solar tracking system and is determined to be the optimal value.