This paper estimates the total effect of power outages on economic growth in Sub-Saharan Africa over the period 1995-2007. Outages are instrumented using a satellite-based measure of lightning density. As suggested by Henderson et al. (2011), we also combine Penn World Tables GDP data with satellite-based data on nightlights to arrive at a more accurate measure of economic growth. Our results suggest that the annual economic growth drag of a weak power infrastructure is about 2 percentage points.