Thus, this paper presents a preliminary analysis of the parameters and their interactions of the welding process (by parallel-gap resistance welding) of interconnections between solar cells using design of experiments. In this welding process, the cell undergoes a certain level of degradation.
The ununiform temperature field, mismatched thermal expansion coefficient and local plastic deformation during welding are the root causes of residual welding stress. The influence of welding process on the yield of solar cells has been discussed above.
The welding strip is an important part of photovoltaic module. The current of the cell is collected by welding on the main grid of the cell. Therefore, this paper mainly studies the influence of different surface structure of heterogeneous welding strip on PV assembly power improvement. The main findings are as follows:
The thickness of silicon wafer is 160 μm, the thickness of PV copper strip is 0.1 mm, the thickness of Sn alloy coating is 15 μm and 25 μm respectively. The physical properties of materials used in solar cell welding are shown in Table 6.
According to IEC61215 standard, the light emitted by solar simulator is vertically incident on the surface of photovoltaic welding strip through glass and EVA. The change of surface structure of photovoltaic welding strip will change the reflection path of light on the surface of photovoltaic welding strip, affecting the size of α 1 in Fig. 1.
The quality of welding strip will directly affect the current collection efficiency of photovoltaic module, so it has a great impact on the power of photovoltaic module. The so-called photovoltaic welding strip is to coat binary or ternary low-melting alloy on the surface of copper strip with given specification.