# Floating Photovoltaic Plant Monitoring: A Review of Requirements and Feasible Technologies
## 7 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Ref.**} & **FPV** & **Water Depth [m]** & **n’** & **n’** & **n’** & **Depths of** & **Monitoring** \\  & **Dim.** & **Max** & **WC** & **Fringe** & **Open Water** & **for Each WC [m]** & **Configuration** \\  & **[ha]** & **(Avg)** & **FPV** & **(dist. from FPV)** & **(dist. from FPV)** & **(dist. from FPV)** & **(low-cost sensors)** \\ \hline \hline \multirow{2}{*}{\begin{tabular}{c} Vlaswinke \\ (2023) \\ (68) \\ (63) \\ \end{tabular} } & \multirow{2}{*}{0.04} & \multirow{2}{*}{22} & 1 & - & (100 m) & 0.6 & Fixed: x, y \\  & & & 1 & - & 1 & each 0.5 & \begin{tabular}{c} Fixed: x, y \\ Mobile (winch): z \\ \end{tabular} \\ Liu & & & 8 & & 3 & 0.5, 2, 3 & Fixed: x, y, z \\  & & & 6 & & 6 & 0.5, 2, 3 & Fixed: x, y, z \\  & & & 6 & & 6 & 0.5, 2, 3 & Fixed: x, y, z \\  & & 70 & 1 & 1 & 1 & each 0.5 & \begin{tabular}{c} Fixed: x, y, z \\ (low-cost sensors) \\ \end{tabular} \\  & & (22) & 1 & Shallow & 1 & 1 & 1 & 0.8 & Fixed: x, y, z \\  & & & & & & 0.2 & Fixed: x, y, z \\  & & & & & & 1.5 & \\  & & & & & 1 & 10 \\ \multirow{2}{*}{\
\begin{tabular}{c} [PERSON] \\ (69) \\ \end{tabular} } & \multirow{2}{*}{18.3} & \multirow{2}{*}{35} & \multirow{2}{*}{1} & \multirow{2}{*}{1} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} \\  & & & & & (100 m) & & & \\ \multirow{2}{*}{
\begin{tabular}{c} [PERSON] \\ (71) \\ \end{tabular} } & \multirow{2}{*}{0.006–0.8} & \multirow{2}{*}{1} & \multirow{2}{*}{1} & \multirow{2}{*}{1} & \multirow{2}{*}{1} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} & \multirow{2}{*}{100 m)} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: State of the art of solutions adopted for WQM in FPV in relation to size and depth of the water body. reported studies using an automated winch, this is a very interesting method to perform autonomous monitoring for small FPV systems when only a reduced number of water columns is required (two or three). A different strategy was employed by [PERSON] et al., who measured vertical profiles of water temperature. In this case, several low-cost sensors were applied at a fixed location on water columns (x, y), each 0.5 m of increasing depths (z). This can be a convenient solution, when water quality monitoring is focused on a single or just a few parameters that can be measured with several cheap sensors distributed in the water body. This solution can guarantee autonomous and continuous monitoring of water quality for a long period without requiring human intervention, and with the help of mapping algorithms, it also allows 3D mapping of the monitored parameters. This approach becomes less sustainable as the number of monitored parameters increases along the vertical profile or when many water columns need to be monitored (as for large FPVs). [PERSON] et al. proposed two different strategies to monitor each water column: four different sensors at fixed depths (1.5 m, 10 m, 20 m, 31.5 m) for continuous and autonomous monitoring, and a single mobile sensor equipped on-board a commercial ROV. The use of the ROV allowed the measuring of the whole vertical profile at depth steps of 1 m of two water columns with a single multiparameter probe. The advantages of this method increase when several water columns must be monitored with multiple parameters throughout the vertical profiles of a water body with a certain depth (>20 m). In this case, the cost of monitoring can be significantly reduced with the use of a robotic device equipped with an expensive multiparameter probe. As, by definition, an ROV requires human control during the monitoring activity, the solution proposed by [PERSON] and colleagues is not suitable when continuous WQM is required for long periods of time. A more advanced robotic solution, though more expensive, may be represented by the use of an AUV as a carrier of sensors for WQM of FPV instead of using an ROV.