Page 78 - Applied Photovoltaics

Figure 4.12. Use of a four point probe to measure the sheet resistivity of a solar
cell.

Using the voltage and current readings from the probe,

ʌ V
ȡ † ȍ (4.7)
†
ln 2 I
where ʌ/ln2 = 4.53.
The typical sheet resistivity of silicon solar cells lies in the range 30–100 ȍ/†.

4.4.2 Grid spacings

Sheet resistivity is important because it determines the spacing between grid lines of
the top contact, as shown in Fig. 4.13.

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