Performance of Framed and Frameless Bifacial PV Modules in the Desert Climate

Rear-side shading and irradiance non-uniformity exert significant influence on energy yield losses and the overall reliability of bifacial photovoltaic (PV) modules. The prevailing causes of the shading and non-uniformity concerns within state-of-the-art PV modules are attributed to the module's design and components such as the module frame, junction box, and Direct Current (DC) cables. These elements collectively impose limitations on the magnitude and distribution of incident irradiance reaching the rear side of the module. In this work, the impact of the module frame on the performance of commercial bifacial Silicon Heterojunction (SHJ) PV modules were studied in detail via controlled indoor characterization as well as outdoor assessments in real desert climate operating conditions, under conventional tilt (22 degrees N-S) and vertical tilt (90 degrees E\W) installations. The results show a substantial deleterious influence of the module frame on critical parameters such as module temperature and electrical characteristics. The average maximum power (Pmax) at the rear of the framed module was significantly lower than that of the front, in contrast to the frameless module. The bifaciality factors for Pmax were 84.1% and 88.5% for the framed and frameless modules, respectively. Under real outdoor test conditions during August to December 2023 and under no intentional cleaning, the frameless module produced 2.3% more energy than the framed module, when in conventional tilt, and 6.0% more energy when installed vertically. The study generates essential information and data for module design, selection and installation configuration in related climatic regions.