Solar panel installations are surging in the U.S. and Europe as Western countries seek to cut their reliance on fossil fuels.

But the West faces a conundrum as it installs panels on small rooftops and in sprawling desert arrays: Most of them are produced with energy from carbon-dioxide-belching, coal-burning plants in China.

Concerns are mounting in the U.S. and Europe that the solar industry’s reliance on Chinese coal will create a big increase in emissions in the coming years as manufacturers rapidly scale up production of solar panels to meet demand. That would make the solar industry one of the world’s most prolific polluters, analysts say, undermining some of the emissions reductions achieved from widespread adoption.

For years, China’s low-cost, coal-fired electricity has given the country’s solar-panel manufacturers a competitive advantage, allowing them to dominate global markets.

Chinese factories supply more than three-quarters of the world’s polysilicon, an essential component in most solar panels, according to industry analyst Johannes Bernreuter. Polysilicon factories refine silicon metal using a process that consumes large amounts of electricity, making access to cheap power a cost advantage. Chinese authorities have built an array of coal-burning power plants in sparsely populated areas such as Xinjiang and Inner Mongolia to support polysilicon manufacturers and other energy-hungry industries.