Short Term Performance and Degradation Trends in Bifacial Versus Monofacial PV Systems: A U.K. Case Study

Abstract

This study presents an empirical analysis of the degradation rates in eight bifacial photovoltaic (PV) systems over the initial two years of operation, comparing glass/transparent-backsheet (G/tB) and glass/glass (G/G) configurations against traditional monofacial systems. Utilizing data from various U.K. locations, we assessed systems using RdTools for degradation rate estimation—a methodology that ensures accuracy by adjusting for environmental factors, such as soiling and irradiance variations. Our findings indicate that the sampled G/tB bifacial systems exhibit higher annual degradation rates (−1.46% to −2.30%), significantly exceeding the solar industry's average (−0.8%), while the G/G configurations in our study show comparatively lower rates (−0.90% to −1.17%). Monofacial systems maintained degradation rates closer to the industry benchmark (−0.62% to −0.94%), suggesting more stable long-term performance. This article contributes novel insights into the comparative durability and efficiency of bifacial versus monofacial PV technologies based on a specific set of systems and emphasizes the critical need for advancements in bifacial system design and material quality to improve their long-term reliability.