Environmental impacts of floating solar photovoltaics on their host water bodies : Opportunities and risks

Exley, Giles and Armstrong, Alona and Folkard, Andrew and Hernandez, Rebecca R and Jones, Ian and Page, Trevor and Thackeray, Stephen (2022) Environmental impacts of floating solar photovoltaics on their host water bodies : Opportunities and risks. PhD thesis, Lancaster University.

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Abstract

Freshwater ecosystems provide services that are essential for human survival. However, as the energy system is decarbonised, the surfaces of inland water bodies are increasingly being transformed to host floating solar photovoltaics (FPV). Water bodies are favoured over conventional ground and rooftop solar PV installations as they conserve limited land resources and provide higher electricity generation efficiencies. However, FPV represents a new stressor to water bodies. The permanent shading and sheltering effects of FPV arrays at the water’s surface pose potential impacts to the functioning of the water environment. To date, impacts on the host environment, both the opportunities and risks, are poorly resolved, in the context of present and future climates. This thesis synthesises scientific and stakeholder knowledge from an evidence review and stakeholder engagement to define modelling experiments that investigate the opportunities and threats of FPV installations and aims to inform best practices and future management decisions. Results reveal the effect of FPV on the water environment scales with coverage extent and siting location. Typically, FPV cools water temperatures, reduces stratification duration, and limits the growth of phytoplankton, with higher coverage leading to greater magnitude changes. Given these physical and biological changes, FPV may have the potential to reduce or offset some of the impacts of climate warming on water bodies, depending on FPV coverage and future emissions concentrations. The results suggest that FPV could be an effective tool for managing water bodies by improving water quality and enhancing ecosystem services. However, host water body response will be highly specific to siting location and coverage of FPV installations. Failing to understand the impacts of a specific FPV installation on the host water body could result in undesirable ecosystem impacts, curtailing this technology’s deployment and slowing the net-zero energy transition.