The concept of a nanostructured-surface/pn junction hybrid solar cell has been modeled to incorporate multiple excitons generation effects. Using the mature silicon solar cell as a base, a nanostructured surface can be made to increase efficient absorption of high energy light by impact ionization induced multiple exciton effects. The nanostructured surface has additional benefits including anti-reflection and a surface field at the quantum confined regions. An ideal detailed-balance efficiency of 41.2% is found for the hybrid solar cell under one sun illumination. This is reduced to 33% when taking into account non-idealities yet both models increase rapidly with concentration as discussed thus motivating a search for the best nanostructured surface to yield multiple excitons generation. A preliminary design of such a surface has been chosen and fabrication is shown.