## 4 Computer Results and Simulations  
EHO variants were tested using 57 mm diameter commercial silicon solar cells from the RTC Company of France to verify their performance against single- and double-diode models. The experiment is carried out under 1 sun (1000 W/m\({}^{2}\)) at 33 \({}^{\circ}\)C [8; 42; 55]. A multi-crystalline PV solar module CS6P-240P is used to represent the three-diode model. CS6P-240P experimental data based on [56; 57] are established for four irradiance levels (109.2, 246.65, 347.8, and 580.3 W/m\({}^{2}\)) at temperatures (37.32, 40.05, 347.8, and 51.91 \({}^{\circ}\)C), respectively. Table 2 shows the manufacture specification for CS6P-240P under standard test conditions (STD). The basic EHO and its three variants are compared with the results of two algorithms from [42] called Artificial Bee Swarm Optimization algorithm (ABSO) and Harmony Search (HS) algorithm. The few adjustable parameters for EHO can be set as \(\alpha=0.9\), \(\beta=0.1\), number of clans = 4, population size = 32, and maximum iteration = 5000. Tables 3 and 4 present the optimal solar cell parameters and RMSE by EHO algorithms, Artificial Bee Swarm Optimization algorithm (ABSO), and Harmony Search (HS) for single- and double-diode modes. The single-diode model is considered the simplest model among all models with only five parameters. Table 3 shows that the four EHO algorithms obtained the same result due to the model's simplicity, but all four algorithms outperformed ABSO and HS. Table 4 shows the results for the double-diode model with seven parameters, showing differences between the extracted parameters and the RMSE. Compared to other algorithms, CEHO achieved the lowest RMSE. Figure 7 shows the convergence of the four EHO algorithms for the single-diode and double-diode model at the first 250 generations, respectively. In addition, it showed the fast convergence of the proposed EHO algorithms for obtaining good results. \begin{table}
\begin{tabular}{l l} \hline \hline Maximum Power at STC & 240 W \\ \hline Optimum operating voltage & 29.9 V \\ \hline Optimum operating current & 8.03 A \\ \hline Open circuit voltage & 37.0 V \\ \hline Short circuit current & 8.59 A \\ \hline V Temperature coefficient \(Voc\) & \(-0.43\%\) \\ \hline I Temperature coefficient \(Isc\) & 0.065\% \\ \hline Cell arrangement & 60 (6 \(\times\) 10) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Manufacture specification under standard test condition. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Item**} & \multirow{2}{*}{**EHO**} & \multicolumn{4}{c}{**EHO Variants**} & \multirow{2}{*}{**ABSO**} & \multirow{2}{*}{**HS**} \\ \cline{3-4}  & & \(\alpha\)**EHO** & & & & \\ \hline \(I_{ph}\) (A) & 0.76078 & 0.76077 & 0.76078 & 0.76077 & 0.7608 & 0.7607 \\ \hline \(I_{d}\) (\(\mu\)A) & 0.32201 & 0.32143 & 0.32098 & 0.320479 & 0.30623 & 0.30495 \\ \hline \(R_{s}\) (\(\Omega\)) & 0.036388 & 0.036397 & 0.0364027 & 0.0364085 & 0.03659 & 0.03663 \\ \hline \(R_{sh}\) (\(\Omega\)) & 53.5851 & 53.58874 & 53.52479 & 53.49828 & 52.2903 & 53.5946 \\ \hline \(n\) & 1.48086 & 1.48068 & 1.48054 & 1.48038 & 1.47583 & 1.47538 \\ \hline \((RMSE)\) & \(9.861\times 10^{-4}\) & \(9.861\times 10^{-4}\) & \(9.861\times 10^{-4}\) & \(9.861\times 10^{-4}\) & \(9.9124\times 10^{-4}\) & \(9.9510\times 10^{-4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison between EHO algorithms, ABS, and HS for single-diode solar cells. As demonstrated by Table 5, the measured current is very close to the calculated current. In addition, cultural-based EHO leads to outperformed results compared with other EHO variants. Figures 8 and 9 show the power and current of the calculated and measured current from cultural-based EHO. Again, the measured and calculated curves are almost identical, while the relative error for the double-diode model for cultural-based EHO is presented in Table 6.  
The previous results were for the PV panels at standard temperature and radiation.