An assessment study of evaporation rate models on a water basin with floating photovoltaic plants

Abstract

Summary Under the general topic of the impact of floating photovoltaics (FPVs) systems on water basins, the present study aims to model and analyze the effect of FPVs on the evaporation rate of water surfaces. The estimation of the evaporation of the water surface of a basin is usually calculated using mathematical evaporation models that require knowledge of some parameters (ie, solar radiation, humidity, air temperature, water temperature, and wind velocity). Thus, in the first section of this study, some evaporative models (EVM) for free water basin have been examined to evaluate which are the environmental variables used. On the basis of this analysis, new numerical models for the calculation of the daily evaporation rate have been developed using the design of experiments (DoE) method (three models) and the linear regression method (two models). The results of the developed models have been compared with the experimental measurements carried out by an evaporimeter; such comparison has highlighted the robustness of the proposed numerical models. Moreover, for estimating the evaporation rate in water basins partially covered by FPVs, further three numerical methods are proposed. Finally, the evaporation rates, arising by the installation of different typology of FPVs on water basins, have been evaluated as function of the energy balance on the water surface. It is possible to highlight that the amount of evaporated water depends not only on the percentage of surface covered but also on the characteristics of floating systems. Covering only 30% of the surface of a basin, it is possible to obtain up to 49% reduction in evaporation.

Save water and energy: A techno‐economic analysis of a floating solar photovoltaic system to power a water integration project in the Brazilian semiarid

“…The evaporation reduction must consider the energy balance of water and the thermal variations between water and floating PV modules. For this, an FSPV that covers 30% of a water basin's surface does not reduce 30% of the evaporation, 22 the reduction of evaporation in covered areas can achieve 95% or less. 98 As disclosed in Section 3.3.1, the area designated for the FSPV is 742 901.8 m 2 or 24% of the water surface, which completely covers the water surface below it because there are platforms between the modules, and the panels are practically horizontally disposed on water surface with the tilt angle of 9 , so the authors assumed that the transmission of solar radiation to the water below the panels is almost zero.…”

“…98 As disclosed in Section 3.3.1, the area designated for the FSPV is 742 901.8 m 2 or 24% of the water surface, which completely covers the water surface below it because there are platforms between the modules, and the panels are practically horizontally disposed on water surface with the tilt angle of 9 , so the authors assumed that the transmission of solar radiation to the water below the panels is almost zero. 22 The water conservation is proportional to the area occupied by the FSPV, 43 but the task of quantifying the evaporation of reservoirs is more complicated because it must consider the extension, the irregular form, the water inflow, infiltration, and precipitation. 47 Hence, the authors applied the mathematical relationship between covered area and evaporation reduction efficiency for partially covered water bodies developed by Reference 99, described by Equation (2).…”

“…21 A preliminary analysis on the PV and wind resources at the chosen site concluded that the wind power would not be technically nor economically feasible. Hence, due to the water crisis and the necessity of preventing the increasing loss of water with evaporation, 19,22 the floating solar photovoltaic (FSPV) system design was considered. The FSPV is capable of generating electricity while isolating part of the water surface from the incidence of solar radiation, which reduces water evaporation.…”

Numerical Simulations of a PV Module with Phase Change Material (PV-PCM) under Variable Weather Conditions

“…Theoretically, the temperature coefficient γ, which relates PV efficiency and cell temperature, ranges from -0.4 to -0.45% ℃. However, an experimental study has shown that this coefficient could rise to -0.65 % ℃ [1].…”

Transient Analysis of Photovoltaic Module Integrated with Phase Change Material (PCM)

“…As the rise in the temperature of photovoltaic (PV) cells leads to a decrease in the solar to electricity conversion efficiency, many methods have been planned to cool the PV cells [1,2], as well as for increasing their efficiency [3].…”