The modules with holes on the counter electrode substrate for photocurrent collection with thin wires were investigated by simulation. This type of module can perform high efficiency for its high open area ratio. An improved model based on our previous work was used to optimize this type of module. By simulation, we found that hexagonal cell is the best choice for this kind of module, and the optimized length of silver finger is related to the assemblage technique. Open area ratio of more than 90% and aperture area efficiency of more than 10% can be easily achieved based on the small area cell with efficiency of 11.1%. (C) 2012 Elsevier B.V. All rights reserved.