The recent important issue in solar cell fabrication is to adopt thin film silicon solar cells on cheap substrates. However, thin cells demand new grid design concept that all the contacts(to the emitter and base) be located on the front surface. Hence, the aim of the investigation presented in this paper was to determine the potential and the basic limitation of the design. With this concept, an interdigitated front grid structure was realized and cells were fabricated through a set of photolithography processes. Confirmed efficiencies of up to 11.5% were achieved on bonded SOI wafers with a cell thickness of 50$mu extrm{m}$ in the case of finger spacing more than $mu extrm{m}$ and a base width of 35$mu extrm{m}$. It was also shown from the results that the design rules for optimizing the base fraction and reducing the shadowing fraction are noted as an important technique to realize high-efficiency thin silicon solar cells.