- We report the effects of concentrated sunlight on key photovoltaic parameters and stability of organic photovoltaics (OPV). Sunlight collected and concentrated outdoors was focused into an optical fiber and delivered onto a 1 cm2 bulk-heterojunction cell. Sunlight concentration C was varied gradually from 0.2 to 27 suns. Power conversion efficiency exhibited slow increase with C that was followed by saturation around 2% at C=0.5–2.5 suns and subsequent strong reduction. Possible OPV applications in stationary solar concentrators (C≤2 suns) are discussed. Finally, experiments at C=55–58 suns demonstrated potential of our approach for accelerated studies of light induced mechanisms in the OPV degradation.