Performance of Monofacial and Bifacial Silicon Heterojunction Modules under Desert Conditions and the Impact of PV Soiling

Abstract

The performance and reliability of photovoltaic (PV) modules in a desert climate depends, among other factors, on the solar irradiance, operating temperature, and soiling rate. Since the impacts of these environmental factors depend on the type of PV module technology, an assessment of the PV technology to be deployed in the desert climate is crucial for the bankability of PV projects. In this work, the indoor and outdoor performance of monofacial and bifacial silicon heterojunction PV module technologies were assessed. For the indoor measurements, a comparison of the current-voltage (IV) characteristics was performed at standard testing condition and at different temperatures. The two module technologies showed similar temperature coefficients and expected performance within the measurement uncertainty. Comparing the specific energy yield of the modules installed in the Outdoor Test Facility (OTF), the bifacial module showed a 15% higher energy yield than the monofacial module and is attributed to the contribution of the bifacial rear side, thanks to the reflected irradiance received by the bifacial module and the high albedo of 0.43 measured at the OTF. Moreover, the bifacial module was found to be less sensitive to the PV soiling than the monofacial module. The results showed that the frequency of module cleaning could be reduced for the bifacial module compared with the monofacial module, resulting in a remarkable decrease in the module cleaning cost and PV site Operation and Maintenance cost.