Many manufacturers choose the passivated emitter and rear cell (PERC) approach in order to surpass the 20% cell efficiency level in mass production. In this paper, we study the efficiency potential of the PERC approach under realistic assumptions for incremental improvements of existing technologies by device simulations. Based on the most recent published experimental results, we find that the PERC structure is able to reach about 24% cell efficiency in mass production by an ongoing sequence of incremental improvements. As a guideline for future developments, we provide a method to improve cell efficiency most effectively by monitoring the current losses at the maximum power point. By means of numerical device modeling, we identify some key technologies toward 24% efficient PERC cells and provide its technology-related target requirements.