The dramatic growth of the photovoltaic (PV) industry—accelerated by increased economies of scale, technology improvements, research and development efforts, and strong policy support—has pushed PV to set out on its pathway to becoming a major electricity source. The speed and course of this pathway will be determined by the development of PV energy price and its relation to market electricity sales price. The current gap between PV energy price and market electricity sales is often covered by substantial government subsidies. Using the United States PV market as a case study to illustrate the need for PV energy price decline, this article details the potential contribution of high-efficiency PV based on different materials to realize such a decline and a substantial PV electricity share. It is found that—with considerable government support—PV's electricity share in the United States can rise to 25% by 2050. In order to help the PV industry achieve significant progress without large government subsidies, more radical decline of PV system cost is necessary. As such, quantitative analysis is deployed to investigate the value of module efficiency in lowering the total PV electricity cost through a levelized cost of energy analysis. Next, the article investigates in detail the research and development opportunities for high-efficiency PV and projects the required efficiency-price ranges for different types of PV modules.