When the satellites zoomed in, you could see the panels gleaming from space. Pairing images taken miles above the Earth with Chinese customs records, Bloomberg NEF solar analyst Jenny Chase and her team discovered this year that the rooftops of homes and factories across Pakistan are blanketed with solar panels. Catching their own government by surprise, Pakistanis have been installing a massive amount of solar power.

In the process, Pakistan has gone from an inconsequential solar market to the sixth-largest in the world. The country of 242 million has a power grid with a peak capacity of 46 gigawatts — that’s less than 4 percent of the US power supply for a country with more than two-thirds as many people. In the last three years, Pakistanis have imported more than 25 gigawatts of solar panels from China. This disorganized, bottom-up boom has increased Pakistan’s power supply by 50 percent.

The solar surge is driven by high local electricity costs. At 16.6 cents per kilowatt-hour, Pakistan’s electricity rate for businesses is 37 percent […]