# Cell/Module Integration Technology with Wire-Embedded EVA Sheet
###### Abstract  
Silicon wafers are crucial for determining the price of solar cell modules. To reduce the manufacturing cost of photovoltaic devices, the thicknesses of wafers are reduced. However, the conventional module manufacturing method using the tabbing process has a disadvantage in that the cell is damaged because of the high temperature and pressure of the soldering process, which is complicated, thus increasing the process cost. Consequently, when the wafer is thinned, the breakage rate increases during the module process, resulting in a lower yield; further, the module performance decreases owing to cracks and thermal stress. To solve this problem, a module manufacturing method is proposed in which cells and wires are bonded through the lamination process. This method minimizes the thermal damage and mechanical stress applied to solar cells during the tabbing process, thereby manufacturing high-power modules. When adopting this method, the front electrode should be customized because it requires busbarless solar cells different from the existing busbar solar cells. Accordingly, the front electrode was designed using various simulation programs such as Griddler 2.5 and MathCAD, and the effect of the diameter and number of wires in contact with the front finger line of the solar cell on the module characteristics was analyzed. Consequently, the efficiency of the module manufactured with 12 wires and a wire diameter of 0.36 mm exhibited the highest efficiency at 20.28%. This is because even if the optical loss increases with the diameter of the wire, the series resistance considerably decreases rather than the loss of the short-circuit current, thereby improving the fill factor. The characteristics of the wire-embedded ethylene vinyl acetate (EVA) sheet module were confirmed to be better than those of the five busbar tabbing modules manufactured by the tabbing process; further, a high-power module that sufficiently compensated for the disadvantages of the tabbing module was manufactured. crystalline silicon solar cell; module; wire-embedded EVA sheet module; simulation; efficiency +
Footnote †: journal: Applied  
bacteria on the thin wafers. Accordingly, there is a loss in module production yield [8; 9]. Therefore, various methods for a new module process have been proposed to minimize the negative factors affecting the cell and overcome the problems of the existing module process [10; 11; 12]. Among various module manufacturing methods, a module method using a wire can minimize negative factors affecting the cell and overcome the problems of the existing module process. According to the reference literature, it is a module method that is more competitive than modules manufactured using the conventional tabbing method, and the module manufacturing method using wire can greatly save the silver cost of the busbar [12; 13; 14]. In [15], a module manufacturing method that could improve the characteristics of a module through a simple manufacturing process and low cost was proposed. In conventional modules, the cells are connected using a ribbon. In the proposed module, the cells were connected using a circular-shaped wire, and a wire-embedded EVA sheet module was manufactured by interconnecting the cell and wire during the lamination process. The wire-embedded EVA sheet module can minimize the electrical loss by reducing the resistance of the finger in the cell. The wire-embedded EVA sheet can freely control the number of wires, and if the number of wires is large, the length of the finger electrodes between the wires decreases. Accordingly, the resistance to the finger electrode was reduced, thereby minimizing the electrical loss. It is possible to manufacture a high-power module by reducing the shading loss through the re-incidence of light reflected along the wire curve.