Haining, ChinaThe squares of silicon are hardly thicker than sheets of paper, each about six inches by six, with narrow stripes of silver. They come into the factory by the thousands, stacked in cardboard boxes, and within hours, they’ll be ready to leave again.

The squares are solar cells, and in this plant two hours’ drive from Shanghai, workers in bright blue uniforms and white lab coats run the machines that assemble them, row by row, into more familiar-looking panels, ready to be installed on rooftops or in large arrays and begin turning sunlight into electricity.

Chinese manufacturing has changed the economics of renewable power around the world, making solar generation cost-competitive with electricity from fossil fuels like natural gas and even coal.