Current realities and future prospects for high-efficiency solar cells

This paper presents an overview of progress to develop high-efficiency solar cells for space applications. The story is a progression of cells with increasing efficiencies, developed with relatively modest amounts of research dollars, and is a good example of a research community responding to real-world needs. The paper outlines a brief history that shows increases from 10-percent-efficient Si cells to 25-percent Ga/sub 0.5/In/sub 0.5/P-GaAs tandems. Niche application and some trade-offs are discussed. Trends in research to develop even higher efficiencies, extending above 30 percent, are described and offer exciting possibilities for the future, near-term and more distant.