## 4 Discussion
### Methodology for Determination of Equatorial Efficiency  
It is clear that to determine a correct value of weighted efficiency for the Equatorial region, it is necessary to modify the weightage for each level of operation. If the original value of weightage (from \(\eta_{EURO}\)) is used, it will result in a different value. This is shown by the discrepancies between \(\eta_{EURO}\) and \(\eta_{EURO\_real}\) in Table 4. Thus, to formulate the Equatorial efficiency (\(\eta_{EQUA}\)), a new set of weightage needed to be determined. However, to maintain consistency with \(\eta_{EURO}\), six levels of operation with similar \(P_{dd}/P_{dc\_nted}\) range (as shown in Table 1) were used. Recall that the weightage is \(T_{n}\)/\(T_{WT}\), where \(T_{n}\) is the duration at which the inverter operates at a certain irradiance level and \(T_{WT}\) is the entire duration of the inverter operating time. Figure 9 illustrates the irradiance-duration curve produced by the SB300 HF inverter constructed from the one year Equatorial irradiance data from the weather station [6; 7; 8]. Based on the gathered data, the \(P_{dd}/P_{dc\_nted}\) values were grouped into six level of operations. The duration for each level is denoted by \(T_{1}\), \(T_{2}\),..., \(T_{6}\). For example, for \(T_{5}\) the level of operation is 50%. The amount of time in which the inverter operates in this condition (over the entire duration) is 43%. Thus, the weightage for this level \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Efficiency Type** & **SB700 LF** & **SB3000 HF** & **K4200 TL** & **K7900 TL** \\ \hline \(\eta_{EURO}\) (\%) & 92.00 & 95.40 & 95.90 & 96.20 \\ \(\eta_{EURO\_real}\) (\%) & 89.94 & 95.13 & 94.56 & 94.68 \\ Difference (ppt) & 2.06 & 0.27 & 1.34 & 1.52 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Differences between \(\eta_{EURO}\) from the datasheet and \(\eta_{EURO\_real}\). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{_LO_} & \multirow{2}{*}{\(P_{dd}/P_{dc\_nted}\)} & \multicolumn{4}{c}{**SB700 LF**} & \multicolumn{4}{c}{**SB3000 HF**} & \multicolumn{4}{c}{**K4200 TL**} & \multicolumn{2}{c}{**K7900 TL**} \\ \cline{3-10}  & & **Range** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** & **WT (\(\star\))** \\  & & & **(\is 0.43. Similar evaluations can be made for other levels of operation: the weightage for every level of operation can be written as 0.9, 0.8, 0.9, 0.13, 0.43, and 0.18. The other important variables of the weighted efficiency are the \(\mathrm{P_{ac}}\) and \(\mathrm{P_{dc}}\) measurements. They have to be measured at every value of \(P_{dc}/P_{dc\_rated}\). For every level of operation, the \(P_{dc}/P_{dc\_rated}\) was confined within a certain range, as shown in Table 5. Thus the efficiency calculations within this range have to be averaged--similar to the ones performed for \(\eta_{EURO\_recal}\). The summation of the multiplication between \(\eta_{meas\_are}\) and weightage results in the weighted efficiency of the inverter. The final values of \(\eta_{EQUA}\) for SB3000 HF, SB700 LF, K4200 TL, and K7900 TL are shown in Tables 5-8, respectively. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Level of Operation** & **Range of** & & & \\
**(LO) (\%)** & \(\mathbf{P_{dc}/P_{dc\_rated}\) (\%)} & **Weightage (WT) (c)** & \(\eta_{meas\_are}\) (\%) & \(\mathbf{WT\times\eta_{meas\_are}}\) \\ \hline
5 & 0–7.5 & 0.08 & 62.88 & 5.0304 \\
10 & \textgreater{}7.5–15 & 0.09 & 84.69 & 7.6221 \\
20 & \textgreater{}15–25 & 0.10 & 89.50 & 8.9500 \\
30 & \textgreater{}25–40 & 0.15 & 91.48 & 13.7220 \\
50 & \textgreater{}40–75 & 0.47 & 91.65 & 43.0755 \\
100 & \textgreater{}75 & 0.11 & 91.01 & 10.0111 \\ \(\eta_{EQUA}\) (\%) & & & 88.4111 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Weighted efficiency for the SB700 LF inverter when \(G=Gi\) and \(T=25\)\({}^{\circ}\)C with individual weightage. Figure 9: The irradiance-duration curve produced by the SB3000 HF inverter.