## 3 Results
### Parametric Analysis of the PV  
The electrical performance of the different examined PV configurations is given in this section. The analysis is parametric and was conducted for various ambient temperatures, from 0 \({}^{\circ}\)C up to 35 \({}^{\circ}\)C, while two typical incident solar irradiation levels were examined. Specifically, a low solar irradiation level at 400 W/m\({}^{2}\) and a high solar irradiation level at 800 W/m\({}^{2}\) were investigated in this parametric work. The application of the different PV cell cooling techniques aimed to reduce cell temperature. Thus, the results of this section regard the cell temperature variation and also the PV electrical performance for the different conditions. Figure 12 illustrates the cell temperature variation of the different PVs for \(\rm G_{T}=400\) W/m\({}^{2}\) and for different ambient temperatures. For all the PV designs, the rise in the environmental temperature led to higher cell temperature, which is a reasonable result. Moreover, it is interesting that the simple PV led to similar cell temperatures compared to the radiative and the finned cases, with the simple PV presenting a slightly higher cell temperature. Between radiative and finned PV, the finned PV led to a slightly lower temperature but with a very rough difference. On the other hand, the PCM PV had a different behavior and led to a significantly lower cell temperature in colder ambient conditions (approximately up to 20 \({}^{\circ}\)C), while in higher ambient temperatures, the PCM PV clearly led to lower efficiencies. These results indicate that the PCM is a very good cooling technique in hot climates. Practically, the melting temperature of the PCM was selected at 25 \({}^{\circ}\)C, and in lower ambient temperatures, the PCM existence acted as insulation in the system, blocking the cooling of the photovoltaic cell. However, in higher ambient temperatures, the PCM helped the cell be effectively cooled and not influenced by the warm ambient temperatures. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Parameter** & **Athens** & \multicolumn{2}{c}{**Barcelona**} & \multicolumn{2}{c}{**Munich**} & \multicolumn{2}{c}{**Stockholm**} \\ \hline
**(kWh)** & **B1** & **B2** & **B1** & **B2** & **B1** & **B2** & **B1** & **B2** \\ \hline Heating load & 23,669 & 16,585 & 25,927 & 21,632 & 35,570 & 30,725 & 37,879 & 32,651 \\ \hline Cooling load & 31,834 & 14,337 & 22,191 & 6038 & 65,01 & 645 & 3799 & 76 \\ \hline DHW load & 15,748 & 15,748 & 16,960 & 16,960 & 21,236 & 21,236 & 22,301 & 22,301 \\ \hline Electricity for heating & 5266 & 3643 & 6084 & 5017 & 9524 & 8583 & 9999 & 9035 \\ \hline Electricity for cooling & 5885 & 2773 & 3712 & 1058 & 841 & 85 & 484 & 10 \\ \hline Electricity for DHW & 2935 & 2935 & 3317 & 3317 & 4939 & 4939 & 5370 & 5370 \\ \hline Electricity for appliances & 6871 & 6871 & 6871 & 6871 & 6871 & 6871 & 6871 & 6871 \\ \hline Electricity for lighting & 6368 & 6368 & 6368 & 6368 & 6368 & 6368 & 6368 & 6368 \\ \hline Total electricity & 27,324 & 22,590 & 26,352 & 22,631 & 28,543 & 26,846 & 29,092 & 27,654 \\ \hline Mean COP & 4.495 & 4.553 & 4.262 & 4.312 & 3.735 & 3.580 & 3.788 & 3.614 \\ \hline Mean EER & 5.410 & 5.169 & 5.978 & 5.709 & 7.728 & 7.595 & 7.848 & 7.545 \\ \hline \end{tabular}
\end{table} 
Table 6: Summary of the loads and the electricity demands for the examined buildings. Figure 13 shows the PV cell electrical efficiency results of the examined cases with \(\mathrm{G_{T}=400~{}W/m^{2}}\) and for different ambient temperatures. The value of 400 \(\mathrm{W/m^{2}}\) was selected as a low value of PV incident radiation, representing an average cloudy day. The behavior of the simple, radiative and finned PV demonstrated similar performance, with the finned PV being the most efficient choice, the radiative PV the second choice and the simple being the third choice among them.