The lights are going on all over Africa, home to some of the fastest growing economies in the world. Overall, that is great news. Children can study at night without breathing harmful or environmentally damaging kerosene fumes; the sense of security in poor communities, where people live in fear when night falls, is hugely increased; productivity for businesses improves as they can stay open later; and commonplace fires, caused by fallen candles or spilt fuels, become rare.