# Cell/Module Integration Technology with Wire-Embedded EVA Sheet
## 3 Results
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Value (Unit)** & **Parameters** & **Value (Unit)** \\ \hline Sheet resistance (\(R_{S}\)) & 120 (\(\Omega\)/sq) & Wire thickness (\(t_{\omega}\)) & \(2\times 10^{-2}\) (cm) \\ Finger count (\(n\)) & 90 (ea) & Finger width (\(\omega_{f}\)) & \(3\times 10^{-3}\) (cm) \\ Contact resistivity (\(\rho_{c}\)) & 6.2 \(\times\) 10\({}^{-4}\) (\(\Omega\)-cm\({}^{2}\)) & Wire material resistivity (\(\rho_{\omega}\)) & \(1.69\times 10^{-6}\) (\(\Omega\)-cm) \\ Finger material resistivity (\(\rho_{f}\)) & 3.83 \(\times\) 10\({}^{-6}\) (\(\Omega\)-cm) & Wafers resistivity (\(\rho_{b}\)) & 1.3 (\(\Omega\)-cm) \\ Finger thickness (\(t_{f}\)) & 2 \(\times\) 10\({}^{-3}\) (cm) & Wafers (L) & \(1.7\times 10^{-2}\) (cm) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Equation parameters. Figure 7: The ratio of shading and resistance losses with respect to the number of wires. simulation results, a module was fabricated using wires of three diameters. As shown in the simulation results, the number of wires was changed from 6 to 24 to include the number of wires between 10 and 12. Figure 8 shows the characteristics of a module manufactured as a \(1\times 1\) unit module based on the wire diameter and number of wires. Under the conditions of three diameters, the rate of increase or decrease in efficiency of the number of wires showed a similar tendency, and the efficiency of the \(1\times 1\) unit module having a wire diameter of 0.36 mm and 12 wires showed the highest efficiency, at 20.28%. This is explained in Figure 9.  
The change in the short-circuit current was small, and the fill factor was greatly improved as the diameter increased. Although the optical loss increases as the wire diameter increases, the short-circuit current loss is small. As the diameter of the wire increases, the series resistance component significantly decreases, thereby improving the fill factor [25; 26]. In addition, the efficiency of the module was also affected by the number of wires, and the highest efficiency was achieved when the number of wires was 12. The  
Figure 8: Characteristics of a \(1\times 1\) unit module based on the number of wires (**a**) and the wire diameter (**b**). Figure 9: Schematic of the cause of the increase or decrease in efficiency based on the number of wires. lowest efficiency was observed when the number of wires was 6, and the efficiency started to decrease as the number of wires increased to 12 or more. Figure 9 compares the results obtained when the number of wires is large and small. When the number of wires was large, the length of the finger electrode between the wires decreased. Accordingly, the resistance of the finger electrode decreased, although the optical loss was owing to the increased shading area. Conversely, as the number of wires decreased, the shading area decreases and optical loss decreased; however, the length of the finger electrode between the wires increased, indicating that the resistance of the finger electrode increased [27; 28; 29]. The 1 \(\times\) 1 unit module was manufactured based on the diameter and number of wires, and the characteristics of the module were analyzed. A 2 \(\times\) 2 unit module was manufactured by connecting the busbarless cells in series, and at this time, a comparative analysis was conducted based on the characteristic analysis result of the 1 \(\times\) 1 unit module. Figure 10a shows the characteristics of a 2 \(\times\) 2 unit module manufactured according to the number of wires. In the result of the 2 \(\times\) 2 unit module characteristics, the highest efficiency was observed when the number of wires was 12, and the result was similar to the characteristics of the 1 \(\times\) 1 unit module. The open-circuit voltage was similar to that of the wire; however, the short-circuit current decreased owing to shading loss. However, even if there is a loss owing to the short-circuit current, the overall efficiency increases owing to the increase in the fill factor.