The hydrodynamic, thermodynamic, and mixing impacts of floating photovoltaics on the surface of a lake

Abstract

The use of floating photovoltaic panels (FPVs) on lakes and reservoirs is expanding globally. However, their impacts on water column motion, mixing, and thermal stratification remain poorly understood, often characterized by overly simplistic modeling approaches. Here, three-dimensional simulations, supported by analytical calculations, are used to understand the internal transport processes and mixing dynamics of an idealized lake with anchored floating structures under a range of conditions. The effects of FPVs on lake physics include: (a) increased thermal inertia with greater areal coverage, delaying and attenuating seasonal oscillations; (b) perturbations in surface equilibrium temperatures; (c) altered surface heat fluxes in uncovered areas due to lateral heat redistribution, resulting in either increased (conductive FPVs) or decreased (insulating FPVs) near-surface temperatures; (d) reduced vertical mixing rates and mixed layer depths, depending on areal coverage and spatial arrangement of the FPVs in relation to the boundaries; (e) changes in the internal dynamics and velocity fields of the lake in response to the spatial arrangement of the devices; (f) higher rates of mechanical energy exchange across the air-water interface and greater horizontal transport between covered and uncovered regions for lower areal coverages; and (g) a greater fraction of the mechanical energy flux into the lake being used to enhance lateral transport rather than vertical mixing.