# Enhancement of PV Panel Power Production by Passive Cooling Using Heat Sinks with Perforated Fins
## 3 Materials and Methods
### Numerical Simulation
The material properties used in the simulations are shown in Table 2, and the sketch of the model is presented in Figure 3.  
Figure 2: Mesh independence study for each model. During the study, the non-perforated heat sinks were compared with perforated heat sinks in order to determine the optimum configuration for implementation in NOCT conditions of wind. Simulations were realized in steady state conditions with the following input parameters:  
* ambient temperature, \(t_{air}\) = 20, 25, 30 and 35 \({}^{\circ}\)C;
* velocity of the air towards the back of the photovoltaic panel, \(v_{air}\) = 1-5 m/s;
* the normal component of solar radiation varied between 200-1000 W/m\({}^{2}\), assuming the typical conditions of operation for the PV panel. It should be mentioned that heat sinks were studied on some of the worst scenarios of temperature operation for the base case. Therefore, some cases with low levels of solar radiation, low ambient temperatures or high wind velocities were excluded from the results presented during the paper. The main outputs of the simulations were:  
* average temperature of the PV panel;
* convective heat transfer coefficients, achieved for both the front and the back of the PV panel or heat sink. Studied Cases  
A total of six configurations of heat sinks were analyzed, plus the base case, these are shown in Table 3. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Material** & \(g\) [mm] & \(\lambda\) [W/m K] & \(\rho\) [kg/m\({}^{3}\)] & \(c_{P}\) [J/kg\(\cdot\)K] \\ \hline Glass & 3.00 & 1.00 & 2300 & 0.50 \\ PV cells & 0.35 & 168 & 2330 & 0.757 \\ EVA & 0.50 & 0.35 & 960 & 2.09 \\ Tedlar & 0.20 & 0.20 & 1500 & 1.20 \\ Copper & 1.00 & 386 & 8960 & 0.376 \\ Air & - & 0.025 & 1.20 & 1.005 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Material properties. Figure 3: Main components of the numerical model. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Case** & **Name** & **Mesh Detail** & **Description** \\ \hline
0 & Base & Pilot photovoltaic panel—normal installation—without cooling solution. \\ \hline
1 & Horiz Simple & Air-cooled photovoltaic panel with heat sink and non-perforforated horizontal (transversal) fins. \\ \hline
2 & Horiz 30 mm & Air-cooled photovoltaic panel with heat sink and perforated horizontal (transversal) fins \(\Phi\) = 30 mm. \\ \hline
3 & Horiz 60 mm & Air-cooled photovoltaic panel with heat sink and perforated horizontal (transversal) fins \(\Phi\) = 60 mm. \\ \hline
4 & Vert Simple & Air-cooled photovoltaic panel with heat sink and non-perforated vertical (longitudinal) fins. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Studied configurations. The position of the PV panel and air circulation was set according to NOCT conditions: the PV panel was tilted at 45\({}^{\circ}\) and wind direction toward the backside of the PV panel (Figures 4 and 5). Heat sinks consist of a metal plate and perforated or non-perforated longitudinal or transversal fins arranged at equal distances of 150 mm from each other (Table 4). Both the base plate and the fins were made of copper. The base plate was in  
Figure 4: Position of the PV panel (fixed, tilted at 45\({}^{\circ}\)): (**a**) top view; (**b**) side view. Figure 5: Base case—PV panel without cooling—3D perspective view. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Case** & **Name** & **Mesh Detail** & **Description** \\ \hline
5 & & & Air-cooled photovoltaic panel with heat sink and perforated vertical (longitudinal) fins \(\Phi\) = 30 mm. \\ \hline
6 & & & Air-cooled photovoltaic panel with heat sink and perforated vertical (longitudinal) fins \(\Phi\) = 60 mm. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._back of the photovoltaic panel. The fins had circular perforations with a diameter of 30 or 60 mm (Table 4). During the study, the fins were arranged longitudinally (vertically--parallel to the length of the PV panel) or transversally (horizontally--parallel to the width of the PV panel).