# Enhancement of PV Panel Power Production by Passive Cooling Using Heat Sinks with Perforated Fins
## 5 Results and Discussion  
Most simulations in the literature were realized by imposing a constant convective heat transfer coefficient (\(h_{c}\)), which determined a quasi-uniform temperature distribution [50]. In the present work, the simulation of the airflow near the PV panel determined a more realistic temperature distribution on its surface compared with the typical approaches [42], while the convective heat transfer coefficient was varying on the PV panel's surface. The results of the simulations consisted of the photovoltaic panel temperature and convective heat transfer coefficient variation, depending on the type of the heat sink. The spectra of the operating temperatures of the PV panels and velocity path lines on the cross-sectional plane were obtained (Table 5). The following images present the qualitative visualization of the results for cases simulated in NOCT configuration: \(t_{air}\) = 20 \({}^{\circ}\)C, \(v_{air}\) = 1 m/s, \(G\) = 800 W/m\({}^{2}\) (Table 5). Figure 7: Validation of the model: (**a**) base case—without heat sink; (**b**) PV panel with heat sink. \begin{table}
\begin{tabular}{c c} \hline \hline
**Front PV Temperature Distribution (\(t_{PV}\) [\({}^{\circ}\)C])** & **Wind Velocity Cross-Section Plane (\(v_{air}\) [m/s])** \\ \hline  
An interesting aspect was recorded on convective heat transfer coefficients. Therefore, for horizontal heat sinks the \(h_{c}\) on the front of the PV panel were much closer to the \(h_{c}\) on the back, compared to vertical ones, where an important difference was recorded. The ambient temperature variation did not seem to change the best configuration (Case 2--horizontal 30 mm). This configuration determined a drop of temperature as presented in Table 6. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Case**} & \multirow{2}{*}{\(\mathbf{v}_{air}\)} & \multicolumn{2}{c}{\(\mathbf{G=600\) W/m\({}^{2}\)}} & \multicolumn{2}{c}{\(\mathbf{G=800\) W/m\({}^{2}\)}} & \multicolumn{2}{c}{\(\mathbf{G=1000\) W/m\({}^{2}\)}} \\ \cline{3-8}  & & \multicolumn{4}{c}{**Drop of \(t_{PV}\) Compared to Base Case, for \(t_{air}\) = 20-35 \({}^{\circ}\)C**} \\ \cline{3-8}  & & \({}^{\circ}\)**C** & **\%** & \({}^{\circ}\)**C** & **\%** & \({}^{\circ}\)**C** & **\%** \\ \hline
0. BASE CASE & & 40.3–55.9 & - & 47.2–62.9 & - & 54.1–70.1 & - \\ \hline
1. HORIZ SIMPLE & & –6.02—8.59 & –14.9—15.4 & –8.22—11.54 & –17.4—18.3 & –10.52—14.46 & –19.4—26.7 \\ \hline
2. HORIZ 30 MM & & –6.97—8.66 & –17.3—15.5 & –9.51—11.63 & –20.2—18.5 & –12.05—14.61 & –22.3—27 \\ \hline
3. HORIZ 60 MM & 1 m/s & –6.35—8.62 & –15.8—15.4 & –8.55—10.05 & –18.1—16 & –10.88—14.54 & –20.1—26.9 \\ \hline
4. VERT SIMPLE & & –5.98—7.2 & –14.8—12.9 & –8.07—9.76 & –17.1—15.5 & –10.25—12.4 & –18.9—22.9 \\ \hline
5. VERT 30 MM & & –4.49—6.4 & –11.1—11.5 & –6.4—8.61 & –13.6—13.7 & –8.51—10.93 & –15.7—20.2 \\ \hline
6. VERT 60 MM & & –5.82—6.97 & –14.4—12.5 & –7.84—8.59 & –16.6—13.7 & –9.97—10.87 & –18.4—20.1 \\ \hline \end{tabular}
\end{table} 
Table 6: Drop of the PV panel operating temperature for ambient air temperatures, \(t_{air}\) = 20–35 \({}^{\circ}\)C, wind velocity, \(v_{air}\) = 1–5 m/s and solar radiation, \(G\) = 600–1000 W/m\({}^{2}\). Figure 10: Variation of average operating temperature and convective heat transfer coefficient for studied cases (\(G=600\) W/m\({}^{2}\), \(v_{air}\) = 1 m/s and \(t_{air}\) = 20–35 \({}^{\circ}\)C). Figure 9: Variation of average operating temperature and convective heat transfer coefficient for studied cases (\(G=800\) W/m\({}^{2}\), \(v_{air}\) = 1 m/s and \(t_{air}\) = 20–35 \({}^{\circ}\)C). The results showed that for the studied wind conditions, the perforations did not improve the temperature of the PV panel when the fins were vertical. In addition, in the case of vertical fins, the larger perforations (\(\Phi\) = 60 mm) were better, while for the horizontal fins the smaller ones (\(\Phi\) = 30 mm) were better.