Solar Power’s Decade of Falling Costs Is Thrown Into Reverse (1)

A key selling point that made solar energy the fastest-growing power source in the world—rapidly decreasing costs—has hit a speed bump.

Solar module prices have risen 18% since the start of the year after falling by 90% over the previous decade. The reversal, fueled by a quadrupling in the cost of the key raw material polysilicon, threatens to delay projects and slow uptake of solar power just as several major governments are finally throwing their weight behind it in an effort to slow climate change.

“The disruption to solar hasn’t been this bad in more than a decade,” said Jenny ...