Techno-hydrological Attributes and Land Sparing Opportunities of Floating Solar Photovoltaics

Abstract:

Floating solar photovoltaics (FPVs) are increasing in both number and size globally. They have unique attributes relative to ground-mounted solar facilities, owing to their development on the surface of water bodies. Development of FPVs on water can spare land needed for agriculture and conservation; however, a standardized framework for understanding their spatial attributes, especially those related to use efficiency, is lacking. Use-efficiency metrics for FPVs are necessary for elucidating environmental effects of the “footprint” of FPVs and planning sustainable FPV systems. In this study, we compared the techno-hydrological attributes of four FPVs, spanning different climatic regimes, and quantified spatial properties (e.g., surface area, compactness) and land sparing potential for each FPV and associated water body. We then developed water surface-use efficiency (WSUE) metrics for FPVs. We also used PVWatts software to assess optimal panel tilt angle for each of the FPVs; determining that all FPVs had deployed tilt angles ranging 12°-23° from optimal tilt, based on location and historic irradiance and meteorological conditions. Recipient water body types included an irrigation reservoir, water treatment facilities, and a stormwater runoff pond. Land sparing totaled 59.6 km2 across all sites. We found that the average direct capacity-based WSUE among sites is 94.5 ∓ 20.1 W/m2 WSUE is highest at the Windsor, CA site. We calculated that the average total capacity-based WSUE among sites is 33.8 ∓ 24.4 W/m2 and is highest at the Walden, CO site. Our results reveal the diversity of techno-hydrological attributes of FPVs and demonstrate the utility of measuring their spatial attributes, land sparing potential, and WSUE to lay the foundation for further understanding their impacts in aquatic systems and their role in sustainable renewable energy development..