Analysis of current loss from a series-parallel combination of dye-sensitized solar cells using electrochemical impedance spectroscopy

Dye-sensitized solar cells (DSCs) have been proposed as a substitute for silicon crystalline solar cells which have a high manufacturing cost but it is still difficult to fabricate highly efficient DSC module assemblies. Therefore, in this work, an externally connected module assembly was investigated for industrial applications of DSCs. The equivalent circuit of a DSC was determined using typical electrical components and the cause of a current loss in the parallel connection was analyzed using electrochemical impedance spectroscopy. Also, an externally connected module has been constructed using 50 DSCs, where each cell has an active area of 8 cm² (4.62 cm × 1.73 cm) and a conversion efficiency of 4.21% under 1 sun illumination (P_in of 100 mW/cm²). As a result, the externally connected DSC module assembly has an output of 7.4 V and 200 mA, and shows stable performance, with an energy conversion efficiency of 4.44% under 0.45 sun illuminations.