Lake effect or data mirage? How accounting for technology differences at utility scale solar energy facilities can change data interpretation

Abstract As the fastest growing energy source in the United States, utility scale solar energy (USSE) features prominently in the scientific literature, particularly regarding the ‘lake effect hypothesis’, which posits that water birds perceive USSE as water bodies, are subsequently attracted to them, and experience mortality as a result. Policymakers and environmental regulators rely on research to evaluate and publicly disclose the impacts of emerging technologies on wildlife and to craft appropriate avoidance, minimization, and mitigation measures. We completed a literature review and summarized data from two papers to better understand how technology type influences conclusions regarding bird mortality at USSE facilities. We found 16 papers addressing bird mortality at USSE primarily from the United States where authors pooled data across fixed-tilt and single-axis tracker panel photovoltaic (PV) facilities, despite fixed-tilt facilities trending substantially downward in installed capacity in the U.S. in the last 10 years. Our summary revealed that data to support the lake effect hypothesis is sparse when data from fixed-tilt panel facilities developed prior to the commercial transition to anti-reflective coating (ARC) are separated from tracker panel facilities. A dataset from a single fixed-tilt PV facility built prior to the ARC transition was used in eight papers and cited by 14 of the 16 papers that discussed aquatic bird mortality. This single dataset underpins the entire lake effect hypothesis discussion in the scientific literature. Despite this facility being unrepresentative of current USSE facilities, conclusions drawn from these data have been broadly applied to all PV USSE facilities. Overall, our findings show that it is important for researchers to separate data by technology type, and for regulators to understand that avian mortality trends associated with older solar facilities might not be applicable to modern USSE installations.