A novel method for the determination of the front contact resistance in large area screen printed silicon solar cells

The contact resistance at the interface of the semiconductor (Si)/metal (Ag ) contact in a solar cell is generally small because it is made on a heavil y doped silicon surface. In the case of large area terrestrial silicon sola r cells contact is made by screen printing silver paste which has pores eve n after baking and sintering. Therefore the entire area is not active and t he contact resistance is not entirely negligible. This paper describes the use of a simple method for the measurement of contact resistance of the fro nt grid in a large area silicon solar cell based on the application of thre e-point probes using the existing fixed equidistant grid fingers of the sol ar cell. In addition, the value of the sheet resistivity is obtained from t he measurement and is compared with that measured by the standard four-poin t probe method on different samples. The power losses due to current travel ling through different resistive elements in the solar cell were obtained b y using the standard formulae. The calculations show that power loss due to contact resistance is a small part of the total power loss. The total powe r loss agrees with that determined from the illuminated I-V characteristics of the solar cell.