# Selection of a Photovoltaic Panel Cooling Technique Using Multi-Criteria Decision Analysis
## 4 Results and Discussion  
The best and worst cooling strategies for each PV panel cooling method are given in Table 10 below. \begin{table}
\begin{tabular}{l l l l l l l l l} \hline \hline \multirow{2}{*}{**Evaluation Criterion (j)**} & \multicolumn{6}{c}{**Alternative PV Panel Cooling Methods (i)**} \\ \cline{2-9}  & **AFC\({}^{\$}\)** & **HPC** & **PCC** & **TCC** & **TPC** & **FFC** & **WSC** & **ESC** \\ \hline C1 \({}^{\$}\) & 0.1378 & 0.2755 & 0.3444 & 0.2755 & 0.3444 & 0.2411 & 0.5166 & 0.5166 \\ \hline C2 & 0.0000 & 0.3780 & 0.3780 & 0.3780 & 0.3780 & 0.3780 & 0.3780 & 0.3780 \\ \hline C3 & 0.1344 & 0.2689 & 0.3585 & 0.2689 & 0.3585 & 0.0448 & 0.5377 & 0.5377 \\ \hline C4 & 1.0000 & 0.0000 & 0.0000 & 0.0000 & 0.0000 & 0.0000 & 0.0000 & 0.0000 \\ \hline C5 & \(-\)0.0909 & \(-\)0.3636 & \(-\)0.1818 & \(-\)0.3636 & \(-\)0.4545 & \(-\)0.2727 & \(-\)0.4545 & \(-\)0.4545 \\ \hline C6 & 0.0506 & 0.1465 & 0.9813 & 0.0218 & 0.0218 & 0.0593 & 0.0654 & 0.0654 \\ \hline C7 & 0.4508 & 0.3607 & 0.2705 & 0.2705 & 0.3607 & 0.3607 & 0.3607 & 0.3607 \\ \hline C8 & 0.0700 & 0.3501 & 0.2100 & 0.2801 & 0.4201 & 0.1400 & 0.4901 & 0.5601 \\ \hline \hline \end{tabular} Note. \({}^{\$}\) Refer to Table 5.  
\end{table} 
Table 9: Decision matrix \(\mathrm{N_{ij}}\) for PV panel cooling methods. From Table 10, it is evident that for criteria C4, C5 and C8, cooling strategy 1: AFC is best and that this strategy is the worst for criteria C1, C2 and C7. This is supported by the fact that AFC is a reliable cooling method due to its efficient performance in all weather conditions and least impact on the surrounding workspace due to its compactness. AFC is ineffective in hot climatic conditions compared to the other methods and hence it is the worst case in the above-mentioned criteria. While cooling strategies 7: WSC and 8: ESC are best for criterion C3, they are worst for criterion C5. This can be explained by the fact that water spray and evaporative cooling enhances the cooling effect in hot conditions in dry weather compared to other methods. This is because the evaporation rate is high when the ambient conditions are dry and more latent heat of evaporation is need, which produces more cooling. In contrast, corrosion problems, leakages and material degradation, which are associated with the use of water, makes this strategy a poor performer in terms of reliability. Another interesting observation is that thermosiphon cooling is best in terms of cost due to a lesser investment required for the piping and heat transfer arrangements while, understandably, phase change cooling is the worst because of the higher volume requirements and the cost of phase change material. Now, as a decision maker, it is very difficult to reach a unique preference under multiple criteria. So, the closeness to the ideal solution for each alternative PV panel cooling method for a given criterion and the alternative PV panel cooling methods ranking is a must. Therefore, the weights of the scenarios are changed according to the requirement. Here, in this study, six weighting scenarios are adopted (refer to Table 11 below) and the rankings are obtained. As can be seen from Table 11 above, the evaluation ranks of the eight PV panel cooling methods are AFC \(>\) WSC \(>\) TCC \(>\)ESC \(>\) TPC \(>\) PFC \(>\) HPC \(>\) PCC when equal weights are assigned to each criterion. However, it must be accepted that equal weights to all the criteria is an exaggeration, and this scenario is just used as a reference. On the other hand, when the need is to focus on minimizing cost, the preference of the eight PV panel cooling methods is AFC \(>\) TCC \(>\) PFC \(>\) WSC \(>\) ESC \(>\) HPC \(>\) PCC. This clearly indicates that the cost of AFC is minimum due to its minimum investment and maintenance cost. The least preferred in terms of cost is PCC due to the large quantities of phase change material required and its cost. Sometimes, certain operating requirements need a maximization of the efficiency of the cooling system to obtain the maximum power output.