A precise numerical model based on Kirchhoff's laws is used in investigating dye-sensitized solar cell (DSC) modules. As the I-V curve of a small DSC is obtained, the performances of DSC modules with any geometrical character can be exactly simulated by this model. By simulation, we find that the poor synchronization of work status in each cell is the main cause of low efficiency of large area module besides the Joule losses in the resistances. The optimized geometry parameters of the DSC module are mainly influenced by the manufacturing technique rather than the performance of the small cell. Simulation shows that the large area DSC module with aperture area efficiency of 10.57% can be produced based on the small cell with efficiency of 11.1%. (C) 2011 Elsevier B.V. All rights reserved.