Effects of Shunt and Series Resistances on the Performance of a Tandem Solar Cell

This paper investigates the effects of the shunt and series resistances on the performance of a tandem solar cell. There are five output parameters considered as performance indicators of a solar cell: the short-circuit current, the open circuit voltage, the power at the maximum point, the efficiency and the output energy. The performance indicator used in this study is the short-circuit current of the tandem cell as it is directly influenced by the incident irradiance and the power at the maximum point. To observe the changes in the short-circuit current of a tandem solar cell, the shunt resistance of each cell in a tandem solar cell was varied, i. e. in a range of 0 Omega to 10k Omega for the top cell and from 0 Omega to 12k Omega for the bottom cell. The series resistances of the cell were also changes from 0 Omega to 1 Omega for the top cell and from 0 Omega to 2 Omega for the bottom cell. Results of the simulation confirm that while the short-circuit current of such a tandem device is strongly influenced by the lowest current of its sub-cells, a reduction in the shunt resistance of the bottom cell has a positive impact on the overall short-circuit current of device, which increases by almost 9% for the device simulated. Variations in the series resistances have almost no influence on the short circuit of the tandem solar cell.