Challenges remain overcome on the road to manufacturing stable, high-performance organic photovoltaic modules in high volume at low cost. The major challenges are centered on stability to high-intensity solar radiation, which represents one of the many accelerated aging tests, and module efficiency. Several of the underlying problems for both of these will be discussed in the text, and some will be addressed in the following papers. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012