# Effect of Wind Direction and Velocity on PV Panels Cooling with Perforated Heat Sinks
## 3 Materials and Methods  
### Problem Description  
The study was focused on determining the effect of wind direction and velocity over the resulting operating temperatures of PV panels both in cooling and non-cooling conditions (base case). Taking into account the variety of PV panels on the market, a typical one is analyzed (with a power production of 320 W\({}_{\rm p}\) and a surface of 1.6 m\({}^{2}\)). The PV panel is a monocrystalline Si-based one--AE320 HM6-60--Table 1 [32], inclined at 45\({}^{\circ}\) from the horizontal position, in constant solar radiation \(G\) = 1000 W/m\({}^{2}\), constant ambient temperature of \(t_{air}\) = 35 \({}^{\circ}\)C and variable wind direction (from the back, front and side of the PV panel) and velocity (from 1 m/s to 5 m/s). This configuration is also used for validation of the model in NOCT (Nominal Operating Cell Temperature) conditions [31].  
During the study, there were different stages of analysis of the heat sinks attached to the PV panel. The study was initiated with the validation of the model for the base case (no cooling system attached to the photovoltaic panel). After that, a total of six configurations of heat sinks were attached to the PV panel and studied. The various heat sinks were obtained by changing the configuration of their fins. Therefore, for each type of fins (horizontal and vertical), there were the following cases: non-perforated fins vs. fins with perforations of 30 mm and 60 mm diameter (\(\Phi\)).  
The proposed heat sinks are placed in the backside of the PV panel. The contact region is represented by a copper sheet (plate). Perforated or non-perforated copper fins are connected to this plate in order to improve the heat transfer by amplifying the turbulence from the PV panel to the surrounding air (see Figure 1). Therefore, the perforations assure a quantitative and qualitative effect against the heating of the PV panel and could improve the photovoltaic efficiency.  
\begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**AE Solar AE320 HM6-60 PV Panel [32]**} \\ \hline Maximum power \(P_{mp}\) & 320 W\({}_{\rm p}\) \\ Voltage at maximum power \(V_{mp}\) & 33.40 V \\ Current at maximum power \(I_{mp}\) & 9.59 A \\ Open-circuit voltage \(V_{oc}\) & 40.90 V \\ Short-circuit current \(I_{sc}\) & 10.15 A \\ Efficiency \(\eta_{STC}\) & 19.30\% \\ Temperature factor of efficiency \(\beta\) & \(-0.37\%/^{\circ}\)C \\ Nominal operating cell temperature \(t_{NOCT}\) & 47 \({}^{\circ}\)C \\ Dimensions of PV panel (length \(L\)\(\times\) width \(l\)\(\times\) height \(h\)) & 1665 mm \(\times\) 996 mm \(\times\) 35 mm \\ \hline \hline \end{tabular}
\end{table}
Table 1: The electrical and dimensional characteristics of the photovoltaic panel studied.  
Figure 1: The PV panel—heat sink ensemble—Case of vertical fins with perforations.  
The literature analysis showed that the circular holes made in the fins of the heat sinks have the potential to produce promising results for cooling the PV panels [6; 8; 22; 23; 29]. In this case, the resulting temperatures are lower by 2-3 \({}^{\circ}\)C than those obtained by using other shapes for perforations [18]. In the literature are presented various types of fins (continuous, discontinuous or staggered) [33]. During this study, continuous fins of 100 mm height were analyzed.  
Two main configurations of the heat sinks studied were:  
Model 1--**horizontal** fins (3 models: non-perforated, perforated with \(\Phi\) = 30 mm holes and \(\Phi\) = 60 mm holes);  
Model 2--**vertical** fins (3 models: non-perforated, perforated with \(\Phi\) = 30 mm holes and \(\Phi\) = 60 mm holes).