A model has been developed which simulates the effect of cell parameters in order to optimize them by controlling the fabrication conditions, namely, annealing time and annealing temperature. Calculation of the efficiency as a function of surface states density D-it, positive fixed oxide charge density Q(f) and mobile charge density Q(m), that depend on anealing conditions are carried out. A compromise between D-it and Q(m) for different anealing temperatures for high performance cells has been investigated.