Vertical single‐junction silicon photovoltaic cells show a steady increase in open‐circuit voltage with increasing incident light intensity of approximately 0.1 V per decade of intensity, up to approximately 100 W/cm2(∼1000 suns). Voltages as high as 0.76 V have been observed at 25 °C with no apparent saturation of voltage at high intensity. Measurements are presented for cells of various base doping levels. An efficiency of 19.1% has been observed at 76 W/cm2and 25 °C using an unfiltered xenon short‐arc lamp for a nonoptimized cell.