The Saudis burn about a quarter of the oil they produce—and their domestic consumption has been rising at an alarming 7 percent a year, nearly three times the rate of population growth. According to a widely read December 2011 report by Chatham House, a British think tank, if this trend continues, domestic consumption could eat into Saudi oil exports by 2021 and render the kingdom a net oil importer by 2038.

That outcome would be cataclysmic for Saudi Arabia. The kingdom’s political stability has long rested on the “ruling bargain,” whereby the royal family provides citizens, who pay no personal income taxes, with extensive social services funded by oil exports. Left unchecked, domestic consumption could also limit the nation’s ability to moderate global oil prices through its swing reserve—the extra petroleum it can pump to meet spikes in global demand. If Saudi rulers want to maintain control at home and preserve their power on the world stage, they must find a way to use less oil.

Solar, they have decided, is an obvious alternative. In addition to having some of the world’s richest oil fields, Saudi Arabia also has some of the world’s most intense sunlight. (On a map showing levels of solar radiation, with the sunniest areas colored deep red, the kingdom is as blood-red as a raw steak.) Saudi Arabia also has vast expanses of open desert seemingly tailor-made for solar-panel arrays.