**6.4 I-V testing and characterization of solar cells**

The final step is I-V testing of the complete solar-cells as per the standard test conditions (STC), i.e., AM 1.5G, 1000 W/m<sup>2</sup> with a Class AAA solar simulator. An example of FS probing of solar cell is shown in **Figure 21**. The typical parameters obtained from the I-V tester are indicated in **Table 3**. I-V testers have many characterization parameters which can be helpful for diagnosis of solar cell defects. Representative electroluminescence (EL) and thermal IR image of a solar cell with some defects are shown in **Figures 22(a)–(c)**. An EL image of a good solar cell with uniform intensity is shown in **Figure 22(a)**, while for a solar cell in which the FS fingers are not printed uniformly, a darker contrast can be seen in **Figure 22(b)**. **Figure 22(c)** shows a thermal IR image of a solar cell with a localized shunt which has been formed during one of the processing steps. In the end, the solar cells are sorted in different efficiency bins based on the selected classification.

#### **Figure 21.**

*I-V measurement FS probing for solar cell characterization.*


#### **Table 3.**

*Parameters for characterization of a solar cell obtained from I-V measurement.*

**Figure 22.**

*(a) EL image of a good solar cell, (b) EL image of a solar cell with non-uniformity in Ag finger printing and (c) thermal IR image of a solar cell indicating presence of localized shunts.*
